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1
Bertrand, I., R. E. Holloway, R. D. Armstrong e M. J. McLaughlin. "Chemical characteristics of phosphorus in alkaline soils from southern Australia". Soil Research 41, n. 1 (2003): 61. http://dx.doi.org/10.1071/sr02021.
Testo completoAbstract (sommario):
This study was performed to better understand the chemical behaviour of P in a variety of alkaline soils from southern Australia. To do so, surface soil samples of 47 alkaline cropping soils from Upper Eyre Peninsula in South Australia and from western Victoria were collected. The 22 soils collected from Eyre Peninsula were Calcarosols, and those from western Victoria were Vertosols, Alkaline Duplex soils, Sodosols, and Red Brown Calcareous soils. Parameters included total and amorphous Al and Fe, organic C, organic P, CaCO3 content, P sorption characteristics, phosphorus buffer capacity, calcium lactate (Ca-Lac) extractable P, bicarbonate-extractable (Colwell) P, water-extractable P, anion exchange membrane extractable P (AEM-P), and isotopically exchangeable P (labile P). Concentrations of micronutrients in the Calcarosols were relatively low, considered to be a function of low clay contents. Given very low background Cd concentrations in the soils, it was estimated from Cd measurements that the majority of total P in the soils was derived from previous fertiliser applications. Phosphorus buffer capacities (PBCs) were relatively high in the Calcarosols and moderately high in the other alkaline soils. P sorption behaviour in the Calcarosols was a direct function of CaCO3 content, although in the other alkaline soils, amorphous Al and Fe oxides were the principal determinants of the P sorption behaviour. Both Colwell and Ca-Lac extractants dissolved non-labile P in the highly calcareous soils, whereas AEM appeared to only remove surface-adsorbed P. In addition, Colwell P values were positively related to PBC and to the slope term in the Freundlich model (Kf) when Kf > 10. It is suggested that AEM-P may be a better predictor of P availability in highly calcareous soils compared with the other extractants.
2
McBeath, T. M., R. D. Armstrong, E. Lombi, M. J. McLaughlin e R. E. Holloway. "Responsiveness of wheat (Triticum aestivum) to liquid and granular phosphorus fertilisers in southern Australian soils". Soil Research 43, n. 2 (2005): 203. http://dx.doi.org/10.1071/sr04066.
Testo completoAbstract (sommario):
Recent field trials on alkaline soils in southern Australia showed significant grain yield responses to liquid compared with traditional granular forms of P fertiliser. However the advantages of liquid over granular P forms of fertiliser has not been consistent on all soil types. In order to better predict the soil types on which liquid P fertilisers are likely to have potential, a glasshouse trial was conducted to compare the responsiveness of wheat to both liquid and granular forms of P on a wide range of Australian soils. A granular P fertiliser (triple superphosphate) and 2 liquid fertilisers (phosphoric acid and ammonium polyphosphate) were compared at a rate equivalent to 12 kg P/ha in 29 soils representing many of the soil types used for grain production in Victoria and South Australia. Wheat biomass was enhanced by P application in 86% of the soils tested. In 62% of the P-responsive soils, wheat dry matter was significantly greater when liquid P fertilisers were used compared with the granular form. Chemical analysis of the soils tested showed that the better performance of liquid P forms was not correlated to total P concentration in soil, P buffer capacity, or P availability as measured by Colwell-P. However, there was a significant positive relationship between calcium carbonate (CaCO3) content of soil and wheat responsiveness to liquid P fertiliser.
3
Singh, B., e RJ Gilkes. "Phosphorus sorption in relation to soil properties for the major soil types of South-Western Australia". Soil Research 29, n. 5 (1991): 603. http://dx.doi.org/10.1071/sr9910603.
Testo completoAbstract (sommario):
The P sorption characteristics of 97 soils that are representative of the agricultural areas of Western Australia were described using Langmuir and Freundlich equations. The Langmuir P maximum (xm) ranged from 11 to 2132 �g g-1 soil and the Freundlich k coefficient ranged from 1 to 1681. Clay content, DCB Fe and Al, oxalate Fe and AL, and pyrophosphate Al were positively related to xm and k. By using stepwise regression analysis, the combination of DCB and oxalate-soluble A1 predicted more than 75% Of the variation in the P sorption coefficients. Reactive Al compounds may thus be responsible for much of the P sorption by these soils. Soil pH in 1 M NaF (pH 8.2), which is normally used for the detection of allophanic material, was strongly related to the P sorption coefficients and might therefore be used as a quick test for predicting the P sorption capacity of soils.
4
Reuter, DJ, CB Dyson, DE Elliott, DC Lewis e CL Rudd. "An appraisal of soil phosphorus testing data for crops and pastures in South Australia". Australian Journal of Experimental Agriculture 35, n. 7 (1995): 979. http://dx.doi.org/10.1071/ea9950979.
Testo completoAbstract (sommario):
Data from more than 580 field experiments conducted in South Australia over the past 30 years have been re-examined to estimate extractable soil phosphorus (P) levels related to 90% maximum yield (C90) for 7 crop species (wheat, barley, oilseed rape, sunflower, field peas, faba beans, potato) and 3 types of legume-based pasture (subterranean clover, strawberry clover, annual medics). Data from both single-year and longer term experiments were evaluated. The C90 value for each species was derived from the relationship between proportional yield responsiveness to applied P fertiliser rates (determined as grain yield in crops and herbage yield in ungrazed pastures) and extractable P concentrations in surface soils sampled before sowing. Most data assessments involved the Colwell soil P test and soils sampled in autumn to 10 cm depth. When all data for a species were considered together, the relationship between proportional yield response to applied P and soil P status was typically variable, particularly where Colwell soil P concentration was around C90. When data could be grouped according to common soil types, soil surface texture, or P sorption indices (selected sites), better relationships were discerned. From such segregated data sets, different C90 estimates were derived for either different soil types or soil properties. We recommend that site descriptors associated with the supply of soil P to plant roots be determined as a matter of course in future P fertiliser experiments in South Australia. Given the above, we also contend that the Colwell soil P test is reasonably robust for estimating P fertiliser requirements for the diverse range of soils in the agricultural regions of the State. In medium- and longer term experiments, changes in Colwell soil P concentration were measured in the absence or presence of newly applied P fertiliser. The rate of change (mg soil P/kg per kg applied P/ha) appeared to vary with soil type (or soil properties) and, perhaps, cropping frequency. Relatively minor changes in soil P status were observed due to different tillage practices. In developing P fertiliser budgets, we conclude that a major knowledge gap exists for estimating the residual effectiveness of P fertiliser applied to diverse soil types under a wide range of South Australian farming systems.
5
Hart, M. R., e P. S. Cornish. "Comparison of bicarbonate-extractable soil phosphorus measured by ICP-AES and colourimetry in soils of south-eastern New South Wales". Soil Research 47, n. 7 (2009): 742. http://dx.doi.org/10.1071/sr09034.
Testo completoAbstract (sommario):
Soil testing for plant-available phosphorus (P) in Australia is most commonly conducted using alkaline sodium bicarbonate extraction (Olsen or Colwell tests), followed by a colourimetric assay to measure the concentration of P in solution. Analysis by inductively coupled plasma (ICP) spectroscopy has become increasingly popular internationally for other soil P tests, especially Mehlich 3, due to its efficiency and ability to measure multiple elements in the one extract. The use of ICP in place of colourimetry has been used in some Australian laboratories for bicarbonate-extractable P. However, the method is known to measure forms of P (organic) that are not measured by the colourimetric assay. This study presents data comparing soil Colwell P measured by the 2 methods for 714 soil samples from pastoral sites in south-east New South Wales. Measurement by ICP consistently yielded significantly higher P concentrations than the colourimetric method (ICP-P = 1.122Col-P + 57.0, r2 = 0.95, P < 0.001). Differences between the 2 techniques were more marked in 0–20 mm than 0–100 mm depth soil samples, and in soils with greater clay contents, suggesting that the difference was related to soil organic matter, and thereby organic P contents. Relative differences were greatest in soils with lower P concentrations, i.e. within the agronomic optimum range of most interest to farmers. ICP analysis cannot be directly correlated with colourimetrically measured P in bicarbonate extracts, and would need to be developed and calibrated as a separate, new soil P test.
6
McBeath, T. M., M. J. McLaughlin, R. D. Armstrong, M. Bell, M. D. A. Bolland, M. K. Conyers, R. E. Holloway e S. D. Mason. "Predicting the response of wheat (Triticum aestivum L.) to liquid and granular phosphorus fertilisers in Australian soils". Soil Research 45, n. 6 (2007): 448. http://dx.doi.org/10.1071/sr07044.
Testo completoAbstract (sommario):
Liquid forms of phosphorus (P) have been shown to be more effective than granular P for promoting cereal growth in alkaline soils with high levels of free calcium carbonate on Eyre Peninsula, South Australia. However, the advantage of liquid over granular P forms of fertiliser has not been fully investigated across the wide range of soils used for grain production in Australia. A glasshouse pot experiment tested if liquid P fertilisers were more effective for growing spring wheat (Triticum aestivum L.) than granular P (monoammonium phosphate) in 28 soils from all over Australia with soil pH (H2O) ranging from 5.2 to 8.9. Application of liquid P resulted in greater shoot biomass, as measured after 4 weeks’ growth (mid to late tillering, Feeks growth stage 2–3), than granular P in 3 of the acidic to neutral soils and in 3 alkaline soils. Shoot dry matter responses of spring wheat to applied liquid or granular P were related to soil properties to determine if any of the properties predicted superior yield responses to liquid P. The calcium carbonate content of soil was the only soil property that significantly contributed to predicting when liquid P was more effective than granular P. Five soil P test procedures (Bray, Colwell, resin, isotopically exchangeable P, and diffusive gradients in thin films (DGT)) were assessed to determine their ability to measure soil test P on subsamples of soil collected before the experiment started. These soil test values were then related to the dry matter shoot yields to assess their ability to predict wheat yield responses to P applied as liquid or granular P. All 5 soil test procedures provided a reasonable prediction of dry matter responses to applied P as either liquid or granular P, with the resin P test having a slightly greater predictive capacity on the range of soils tested. The findings of this investigation suggest that liquid P fertilisers do have some potential applications in non-calcareous soils and confirm current recommendations for use of liquid P fertiliser to grow cereal crops in highly calcareous soils. Soil P testing procedures require local calibration for response to the P source that is going to be used to amend P deficiency.
7
Lewis, DC, TD Potter, SE Weckert e IL Grant. "Effect of nitrogen and phosphorus fertilizers on the seed yield and oil concentration of oilseed rape (Brassica napus L.) and the prediction of responses by soil tests and past paddock use". Australian Journal of Experimental Agriculture 27, n. 5 (1987): 713. http://dx.doi.org/10.1071/ea9870713.
Testo completoAbstract (sommario):
The response of oilseed rape to applied nitrogen and phosphorus was investigated in 2 areas of the South East of South Australia. The nitrogen rates applied varied from 0 to 50 kg/ha, while phosphorus rates applied in the Mundulla area ranged from 0 to 20 kg/ha and 0 to 34 kg/ha in the Millicent area. At 9 sites in the Mundulla area, where soils were primarily sandy loam over clay, oilseed rape yields were increased significantly by applied nitrogen at 7 sites and by applied phosphorus at 2 sites. On heavy black clay and peat soils in the Millicent area, oilseed rape yields were increased significantly by applied nitrogen at 5 of the 12 sites and by applied phosphorus at 6 sites. Of the measured soil variables, anaerobic ammonium nitrogen measured in the top 10 cm best predicted responses in seed yield to applied nitrogen. The critical nutrient range was 45-65 mg/kg. The response of oilseed rape to applied nitrogen was highly correlated with past paddock use but varied between the 2 areas. From the prediction equations developed, it was concluded that, in the Mundulla area, a significant (P< 0.05) nitrogen response was likely if the oilseed rape followed 2 or more crops, the last a non-legume, but was unlikely if the oilseed rape followed 1 or more years of pasture. At Millicent, a nitrogen response was likely if the oilseed rape was grown as the sixth crop in a continuous cropping program, and was unlikely if it was the first or second crop in the rotation, provided the preceding crop was a non-legume. The response of oilseed rape to applied phosphorus was highly correlated to extractable soil phosphorus measured in the top 10 cm (Colwell). The critical nutrient range was 20-25 mg/kg for the sandy loam soils at Mundulla and 40-50 mg/kg for the black clay and peat soils at Millicent. Nitrogen applications significantly increased seed oil content at 6 sites, significantly decreased it at 2 sites and had no effect at 13 sites. Phosphorus significantly increased seed oil content at only 1 site, significantly decreased it at 3 sites, and had no effect at the other 17 sites.
8
Bolland, MDA, AJ Weatherley e RJ Gilkes. "Residual effectiveness of superphosphate is greater than that of rock phosphate fertilisers for lateritic soils in south-western Australia". Australian Journal of Experimental Agriculture 28, n. 1 (1988): 83. http://dx.doi.org/10.1071/ea9880083.
Testo completoAbstract (sommario):
The residual values of granular reactive rock phosphate (highly carbonate-substituted apatite from North Carolina, USA.), partially powdered low-reactive Queensland rock phosphate (low carbonate-substituted apatite from the Duchess deposit), and granular triple superphosphate were measured in 3 experiments on different lateritic soils in different climatic regions of south-western Australia (Gibson, South Bodallin, West Dale). Finely powdered calcined crandallite-millisite rock phosphate from Christmas Island (Calciphos) was included in one of the experiments. The fertilisers were applied once only in May 1984 and their residual value measured over 3 years (1984-1986) using yield and phosphorus content of the following species each year: experiment 1 (Gibson), barley in years 1 and 2 and oats in the third year; experiment 2 (South Bodallin), triticale in all 3 years; experiment 3 (West Dale), subterranean clover in years I and 2 followed by oats in year 3. Relative to triple superphosphate (TSP) applied each year, the effectiveness of superphosphate in year 1 (year of application) in the experiment at Gibson decreased by about 40% between years 1 and 2, and by a further 5% between years 2 and 3. The corresponding values for the experiment at South Bodallin were 75% and 5%, and at West Dale 50% and 25%. All rock phosphates were much less effective than TSP in year 1, being 5-30% as effective as TSP. Effectiveness of rock phosphates remained low over the 3 years, being 5-20% as effective as newly applied TSP. Although the effectiveness of TSP decreased, it continued to be 50% as effective as newly applied TSP after 3 years. Residual TSP and both freshly applied and residual rock phosphates did not support the same maximum yield as freshly applied TSP despite well defined yield plateaux being obtained in each case. At each harvest, the relationship between yield and phosphorus content of plants was similar for all fertilisers so that the smaller maximum DM and grain yield and reduced effectiveness of the rock phosphates were largely due to less phosphorus being taken up by plants.
9
Evans, C. M., e B. J. Scott. "Surface soil acidity and fertility in the central-western wheatbelt of New South Wales". Australian Journal of Experimental Agriculture 47, n. 2 (2007): 184. http://dx.doi.org/10.1071/ea04165.
Testo completoAbstract (sommario):
Documentation of the chemical fertility status of the soils is sparse for the western and central-western wheatbelt of New South Wales, Australia. We examined properties of the surface soils (0–10 cm) from central-western NSW by collating two published and nine unpublished datasets of soil analyses representing about 2800 soil samples. The emphasis was on the red soils used extensively for cropping. The surface soils of central-western NSW have low phosphorus (47% of soils) and sulfur (70% of soils <5 mg S/kg using KCl-40 analysis) status and commonly have organic carbon contents of about 1%. Surface soil acidity was a substantial problem with 56% of soils (0–10 cm) having a pHCa <5.0. Sodic and dispersive soils are also of concern in this area and these soils have received little attention or research. Approximately 5% of surface (0–10 cm) soils had an exchangeable sodium percentage of ≥6% (sodic). Salinity of surface soils was of minor significance compared with other soil problems in the area, although isolated areas occur. These results indicated that lime applications in this area are likely to benefit crop and pasture production. Additional use of phosphorus and sulfur fertilisers and agricultural practices which increase or maintain organic carbon will also need to be adopted to improve pasture and crop production. The use of gypsum and/or lime on sodic soils may also need to be addressed. As a priority, we suggest that the benefits of lime application to crop yield be examined. The application of lime to the 0–10 cm soil depth should ultimately arrest acidification of the subsurface soil (10–20 cm depth) through downward movement of the lime effect. Further examination of gypsum applications to dispersive sodic soils and the evaluation of sulfur deficiency in the field for pastures and canola are also priority areas of likely agricultural relevance.
10
Bolland, MDA, e MJ Baker. "Increases in soil water content decrease the residual value of superphosphate". Australian Journal of Experimental Agriculture 27, n. 4 (1987): 571. http://dx.doi.org/10.1071/ea9870571.
Testo completoAbstract (sommario):
In pot experiments, levels of superphosphate incorporated through the whole soil were incubated for 30 days in 2 lateritic soils from south-western Australia at 1 of the following 5 soil water contents: air-dry for 30 days, at field capacity for 10 or 30 days, and flooded for 10 or 30 days. The soils were then air-dried for 30 days and the residual value of the superphosphate relative to freshly applied superphosphate was measured using 30-day-old triticale (x Triticosecale cv. Tyalla) and wheat (Triticum aestivum cv. Gamenya) plants. Soil samples were collected just before sowing from each pot for measurement of bicarbonate-extractable phosphorus (P) levels which were compared with the DM yield of plant tops. For all treatments there was a common relationship between the P concentration (data not shown) or P content in the tops and the DM yield. This shows that the treatments can be considered as different dilutions of the same fertiliser. Less P was taken up by plants as the moisture content and period of contact with moist soil increased, and this limited yield. The effectiveness of superphosphate incubated in dry soil was similar to the effectiveness of freshly applied superphosphate. Incubation in moist soil reduced the effectiveness of superphosphate for plant growth, by about 50% for soils incubated at field capacity and 70% for flooded incubated soils. As calculated from the P content of plant tops, the effectiveness of superphosphate incubated in dry soil was similar to the effectiveness of freshly applied superphosphate, and the effectiveness of superphosphate decreased by about 55% for soils incubated at field capacity and 75% for flooded incubated soils. The amount of P extracted by sodium bicarbonate from soil sampled just before sowing was also influenced by the incubation treatments, and decreased in the following order: freshly applied = air dry incubated > field capacity incubated > flooded incubated. Thus the bicarbonate-soluble P extracted from the soil qualitatively paralleled the yield results. However, compared with the yield results, the decreases were not as marked. When the bicarbonate-extracted P results were compared with subsequent yields of triticale or wheat, separate calibration curves were required for the different incubation treatments.
11
Dougherty, W. J., D. M. Nash, D. J. Chittleborough, J. W. Cox e N. K. Fleming. "Stratification, forms, and mobility of phosphorus in the topsoil of a Chromosol used for dairying". Soil Research 44, n. 3 (2006): 277. http://dx.doi.org/10.1071/sr05076.
Testo completoAbstract (sommario):
The forms and stratification of soil phosphorus (P) and their relationship to mobile forms of P were investigated in soils collected from a subcatchment used for grazing of dairy cattle in the Adelaide Hills, South Australia. Phosphorus in the soils was highly stratified. The concentration of calcium chloride extractable P in the 0–0.01 m increment was, on average, 5.7 times greater than in the 0.05–0.10 m increment. Organic P (% of total P) in the top 0.01 m was significantly (P < 0.001) related to soil P content such that low P soils (total P of ~600 mg/kg) had high proportions of Po (~65%), whereas high P soils (total P of ~2000 mg/kg) had low proportions (~25%) of Po. Runoff P from these soils was predominantly (86%) dissolved (i.e. <0.45 μm). There was a significant (P < 0.001) exponential relationship between Olsen P in the top 0.01 m and dissolved P concentration in runoff. The form of dissolved P in runoff from soil in repacked trays was also significantly (P < 0.001) related to soil P. Runoff from low P soils (high Po) had high proportions (>50%) of dissolved unreactive P (DUP), whereas runoff from high P soils (low Po) had low proportions of DUP (<10%). Ultrafiltration of runoff samples revealed that 94 and 65% of the dissolved reactive P and DUP, respectively, was subcolloidal (i.e. <1 nm). These results highlight the relationship between soil fertility, the forms of soil P, and the concentrations and forms of P mobilised in runoff. Such relationships need to be considered in further studies of P mobilisation and the subsequent development of strategies designed to reduce runoff P concentrations.
12
Coad, J. R., L. L. Burkitt e C. J. P. Gourley. "Influence of sample depth on extractable nutrient concentrations, pH and the phosphorus buffering index of pasture soils in south-eastern Australia". Soil Research 48, n. 4 (2010): 355. http://dx.doi.org/10.1071/sr09104.
Testo completoAbstract (sommario):
Pasture soils of mainland Australia are routinely sampled to a depth of 100 mm, whereas pasture soils of Tasmania and New Zealand are sampled to a depth of 75 mm. Despite this difference, there are no published studies to allow accurate conversion between the 2 sampling depths. This study was undertaken to examine the effect of soil sample depth (75 and 100 mm) on soil nutrient analyses: Olsen phosphorus (P), Colwell P, Colwell potassium (K), KCl40 sulfur (S), pH (H2O and CaCl2), and P buffering index (PBI+ColP). Our findings suggest that on most soil types, Olsen P, Colwell P, and Colwell K soil test results could use a generic factor of 1.17 when converting between 75 and 100 mm samples. More detailed equations including direct or indirect measures of soil texture and P sorption capacity were also determined. We found there was no significant difference in P and K concentrations between the different depths in soils which had very low P sorption capacities, high sand contents, and were located in high rainfall zones. Additionally, soil sampling depth generally had no effect on extractable S concentrations, pH, or PBI+ColP, and therefore no conversion is recommended for these soil tests for any soil type.
13
Groves, RH, PJ Hocking e A. Mcmahon. "Distribution of Biomass, Nitrogen, Phosphorus and Other Nutrients in Banksia marginata and B. ornata Shoots of Different Ages After Fire." Australian Journal of Botany 34, n. 6 (1986): 709. http://dx.doi.org/10.1071/bt9860709.
Testo completoAbstract (sommario):
The heathland form of Banksia marginata Cav. regenerates rarely from seed but commonly by resprout- ing from buds on lateral roots, whereas Banksia ornata F. Muell. regenerates only from seed, usually released after fire. The two species co-occur in heath vegetation on nutrient-poor soils in south-eastern South Australia and western Victoria. Shoots were sampled from stands of B. marginata aged from 1 to 25 years and of B. ornata aged from 1 to 50+ years after fire in the Little Desert National Park, western Victoria. B. marginata, the resprouter, distributed a greater proportion of the total shoot dry matter and content of all nutrients to vegetative growth over its shorter life span than B. ornata, the non-sprouter. About 50% of the total phosphorus in B. ornata shoots at 50+ years was present in cones (including seeds) compared with only about 20% in B. marginata shoots at a comparable stage of senescence (25 years). This difference between the species was also true to a lesser degree for nitrogen. There were considerable differences between other nutrients in their distribution patterns in shoots. Nutrients could be grouped together on the basis of distribution in shoots more satisfactorily than on presumed physio- logical roles. Stems were major sites of nutrient accumulation in both species. The content of a particular nutrient in seeds as a proportion of the content in the living parts of the shoot ranged from 0.03% (Na, Mn) to 2.0% (P) in B. marginata, and from 0.3% (Na) to as high as 31% (P) in B. ornata. Concen- trations of all nutrients except sodium were much higher in seeds than in the woody cones or vegetative organs of both species; seeds of B. ornata were particularly rich in calcium and manganese. We conclude that the different patterns of distribution of biomass and nutrients, especially nitrogen and phosphorus, within shoots of the two species reflect their different regenerative modes after fire. Introduction Phosphorus and, to a lesser extent, nitrogen limit the growth of sclerophyllous shrubs on nutrient-poor soils in southern Australia
14
Summers, Robert, Martin Clarke, Tim Pope e Tim O'Dea. "Comparison of single superphosphate and superphosphate coated with bauxite residue for subterranean clover production on phosphorus-leaching soils". Soil Research 38, n. 3 (2000): 735. http://dx.doi.org/10.1071/sr99070.
Testo completoAbstract (sommario):
Bauxite residue from alumina refining was used to coat granules of single superphosphate to reduce the leaching of phosphorus in coarse, sandy soils for pastures in high rainfall areas of south-western Australia (>800 mm annual average). The impact of coating the superphosphate on the leaching of phosphorus was measured in a glasshouse experiment and the effectiveness of the fertiliser using dry herbage yield of subterranean clover (Trifolium subterraneum) was measured in a field experiment. The glasshouse experiment measured the effect of coating the superphosphate with bauxite residue at 0, 5, 10, 15, 20, 25, 30, 35, and 40% by weight. A coating of 25% (by weight) was chosen for the field experiment. In the glasshouse experiment, the coated granules were applied to columns of soil, where subterranean clover was grown under leaching conditions. A coating of 30%, by weight, reduced leaching of single superphosphate by about half. Increasing the coating of bauxite residue also increased the phosphorus uptake and increased the plant growth. In the field trial, the effectiveness of single superphosphate with a bauxite residue coating of 25% by weight was increased on average by 100% in Year 1, 303% in Year 2, and 158% in Year 3, relative to freshly applied single superphosphate. The bauxite residue coating also increased the phosphorus content of the herbage in a similar manner to the increases in yield. Limited soil phosphorus tests showed only minor increases in the residues of phosphorus where the superphosphate had been coated with bauxite residue.
15
Graham, S., B. R. Wilson, N. Reid e H. Jones. "Scattered paddock trees, litter chemistry, and surface soil properties in pastures of the New England Tablelands, New South Wales". Soil Research 42, n. 8 (2004): 905. http://dx.doi.org/10.1071/sr03065.
Testo completoAbstract (sommario):
Scattered paddock trees are widespread throughout rural Australia but their effect on soil conditions has received only limited research attention. This study investigated the influence of 3 Eucalyptus species on surface soil properties on different parent materials at both stocked and unstocked sites on the Northern Tablelands of New South Wales. Mineral soil samples to a depth of 5 cm were collected at intervals up to twice the canopy radius away from tree trunks and litter samples were collected at corresponding points. Mineral soils were analysed for pH (CaCl2), organic carbon (C), and extractable phosphorus (P) concentration, while for the litter samples, P, sulfur, cations, and ash alkalinity were determined. Stocking with sheep and cattle increased surface soil acidity and C and P concentrations at each location. However, soils under E. melliodora and E. viminalis showed higher pH and increased C and P concentrations close to the tree stem irrespective of grazing. Soils under E. caliginosa, while having similar patterns of C and P, showed variable acidity patterns with instances of lower pH close to the tree stem. Spatial patterns in soil acidity were associated with the ash alkalinity of litter, indicating litter as a source of alkalinity addition to the soil surface, although different patterns of soil pH could not be fully explained by litter ash alkalinity alone. The close correlation of litter Ca content with ash alkalinity suggests that this element might be a suitable indicator of the acid amelioration capacity of different tree species.
16
Speirs, Simon D., Brendan J. Scott, Philip W. Moody e Sean D. Mason. "Soil phosphorus tests II: A comparison of soil test–crop response relationships for different soil tests and wheat". Crop and Pasture Science 64, n. 5 (2013): 469. http://dx.doi.org/10.1071/cp13111.
Testo completoAbstract (sommario):
The performance of a wide range of soil phosphorus (P) testing methods that included established (Colwell-P, Olsen-P, BSES-P, and CaCl2-P) and more recently introduced methods (DGT-P and Mehlich 3-P) was evaluated on 164 archived soil samples corresponding to P fertiliser response experiments with wheat (Triticum aestivum) conducted in south-eastern Australia between 1968 and 2008. Soil test calibration relationships were developed for relative grain yield v. soil test using (i) all soils, (ii) Calcarosols, and (iii) all ‘soils other than Calcarosols’. Colwell-P and DGT-P calibration relationships were also derived for Calcarosols and Vertosols containing measureable CaCO3. The effect of soil P buffer capacity (measured as the single-point P buffer index corrected for Colwell-P, PBICol) on critical Colwell-P values was assessed by segregating field sites based on their PBICol class: very very low (15–35), very low (36–70), low (71–140), and moderate (141–280). All soil P tests, except Mehlich 3-P, showed moderate correlations with relative grain yield (R-value ≥0.43, P < 0.001) and DGT-P exhibited the largest R-value (0.55). Where soil test calibrations were derived for Calcarosols, Colwell-P had the smallest R-value (0.36), whereas DGT-P had an R-value of 0.66. For ‘soils other than Calcarosols’, R-values >0.45 decreased in the order: DGT-P (r = 0.55), Colwell-P (r = 0.49), CaCl2-P (r = 0.48), and BSES-P (r = 0.46). These results support the potential of DGT-P as a predictive soil P test, but indicate that Mehlich 3-P has little predictive use in these soils. Colwell-P had tighter critical confidence intervals than any other soil test for all calibrations except for soils classified as Calcarosols. Critical Colwell-P values, and confidence intervals, for the very very low, very low, and low P buffer capacity categories were within the range of other published data that indicate critical Colwell-P value increases as PBICol increases. Colwell-P is the current benchmark soil P test used in Australia and for the field trials in this study. With the exception of Calcarosols, no alternative soil P testing method was shown to provide a statistically superior prediction of response by wheat. Although having slightly lower R-values (i.e. <0.1 difference) for some calibration relationships, Colwell-P yielded tighter confidence intervals than did any of the other soil tests. The apparent advantage of DGT-P over Colwell-P on soils classified as Calcarosols was not due to the effects of calcium carbonate content of the analysed surface soils.
17
Perrett, Christine, Olusegun O. Osunkoya e Cameron Clark. "Cat's claw creeper vine, Macfadyena unguis-cati (Bignoniaceae), invasion impacts: comparative leaf nutrient content and effects on soil physicochemical properties". Australian Journal of Botany 60, n. 6 (2012): 539. http://dx.doi.org/10.1071/bt12055.
Testo completoAbstract (sommario):
Macfadyena unguis-cati (L.) Gentry (Bignoniaceae) is a major environmental weed in coastal Queensland, Australia. There is a lack of quantitative data on its leaf chemistry and its impact on soil properties. Soils from infested vs uninfested areas, and leaves of M. unguis-cati and three co-occurring vine species (one exotic, two native) were collected at six sites (riparian and non-riparian) in south-eastern Queensland. Effects of invasion status, species, site and habitat type were examined using univariate and multivariate analyses. Habitat type had a greater effect on soil nutrients than on leaf chemistry. Invasion effect of M. unguis-cati on soil chemistry was more pronounced in non-riparian than in riparian habitat. Significantly higher values were obtained in M. unguis-cati infested (vs. uninfested) soils for ~50% of traits. Leaf ion concentrations differed significantly between exotic and native vines. Observed higher leaf-nutrient load (especially nitrogen, phosphorus and potassium) in exotic plants aligns with the preference of invasive plant species for disturbed habitats with higher nutrient input. Higher load of trace elements (aluminium, boron, cadmium and iron) in its leaves suggests that cycling of heavy-metal ions, many of which are potentially toxic at excess level, could be accelerated in soils of M. unguis-cati-invaded landscape. Although inferences from the present study are based on correlative data, the consistency of the patterns across many sites suggests that M. unguis-cati may improve soil fertility and influence nutrient cycling, perhaps through legacy effects of its own litter input.
18
Bolland, MDA. "Residual value for wheat of phosphorus from calciphos, Duchess rock phosphate and triple superphosphate on a lateritic soil in south-western Australia". Australian Journal of Experimental Agriculture 25, n. 1 (1985): 198. http://dx.doi.org/10.1071/ea9850198.
Testo completoAbstract (sommario):
The residual values of phosphorus from triple superphosphate and from three rock phosphates were compared in a 4-year field experiment with wheat, grown on a phosphorus deficient lateritic soil in south-western Australia. The three rock phosphate fertilizers were an apatitic rock phosphate originating from the Duchess deposit in north-western Queensland, and calcined (500�C) Christmas Island C-grade ore as a powder and as pellets. Five rates of each fertilizer were applied at the commencement of the experiment and their effectiveness was calculated from data on yield of dried plant tops, grain yield, and bicarbonate soluble phosphorus extracted from the soil. Triple superphosphate was the most effective phosphorus fertilizer initially, but its effectiveness decreased markedly with time. The effectiveness of the three rock phosphates was initially very low, and remained approximately constant for the duration of the experiment. The yield of dried plant tops depended upon their phosphorus content and this relationship was independent of the phosphorus fertilizer used.
19
Scott, B. J., D. J. Carpenter, B. D. Braysher, B. R. Cullis e C. M. Evans. "Phosphorus fertiliser placement for lupins in southern New South Wales". Australian Journal of Experimental Agriculture 43, n. 1 (2003): 79. http://dx.doi.org/10.1071/ea01201.
Testo completoAbstract (sommario):
Research in Western Australia and South Australia indicated that fertiliser phosphorus (P) banded below the seed of narrow leaf lupin (Lupinus angustifolius L.) at sowing was a more effective method of applying P�fertiliser than the usual placement of P with the seed. This technology has not been investigated in southern New South Wales where lupins have been known to be unresponsive to fertiliser P.We conducted 4 field experiments to examine the effect on lupin yield of applying 6 rates of P (0, 5, 10, 15, 20 and 40 kg/ha) either by placement with or below the seed. To further test responsiveness to P, an additional set of treatments was used; applying P at 40 kg/ha before sowing and then placing additional P below the seed at the 6�rates of application. The grain yield of lupin was increased by P application at all sites, despite the medium to high P�status of 3 of the 4 sites used in these experiments. However, the technique of banding P fertiliser below the seed depth rather than placing it in direct seed contact had only a small advantage in grain yield responsiveness to applied fertiliser P (P = 0.09). Fitted response curves indicated that when P was applied at 15 kg/ha, grain yield increased by 60 kg/ha at one site and 30 kg/ha at the other 3 sites, if P was deep-placed rather than applied in seed contact. This advantage of deep placement of P fertiliser was much smaller than has been reported in Western Australia.Placement of P below the seed of lupin when sown on the red earth and red-brown earth soils of southern New South Wales slightly enhanced the availability of fertiliser P. This applied even when sowing was quite shallow (2–3�cm), provided recommended rates of P fertiliser were used at conventional row spacing (17 cm). Separation of seed and fertiliser to avoid reduced germination may be an advantage when using double row spacing and higher P�application rates.
20
Bolland, M. D. A., J. S. Yeates e M. F. Clarke. "Single and coastal superphosphates are equally effective as sulfur fertilisers for subterranean clover on very sandy soils in high rainfall areas of south-western Australia". Australian Journal of Experimental Agriculture 43, n. 9 (2003): 1117. http://dx.doi.org/10.1071/ea02168.
Testo completoAbstract (sommario):
To reduce leaching of phosphorus (P) from fertilised pastures to shallow estuaries in the high rainfall (>800 mm annual average) areas of south-western Australia, and to supply extra sulfur (S) for subterranean clover (Trifolium subterraneum L.) in pasture, 'coastal superphosphate' was developed as a possible alternative P and S fertiliser to single superphosphate. Coastal superphosphate is made by adding phosphate rock and elemental S to single superphosphate as it comes out of the den before granulation. It has about 3 times more sulfur (S) and one-third the water-soluble P content than single superphosphate. Four long-term (5-year) field experiments were conducted in south-western Australia to compare the effectiveness of single and coastal superphosphate as S fertilisers for subterranean clover pasture grown on very sandy soils that are frequently S deficient after July each year due to leaching of S from soil. Seven different amounts of S were applied as fertiliser annually. Fertiliser effectiveness was assessed from clover herbage yield and S concentration in dried herbage. Fertiliser nitrogen was not applied in these experiments as this was the normal practice for pastures in the region when the research was conducted.Both coastal and single superphosphates were equally effective per unit of applied S for producing dried clover herbage and increasing S concentration in herbage. Previous research on very sandy soils in the region had shown that coastal superphosphate was equally or more effective per unit of applied P for production of subterranean clover herbage. It is, therefore, concluded that coastal superphosphate is a suitable alternative S and P fertiliser for clover pastures on very sandy soils in the region. The concentration of S in dried clover herbage that was related to 90% of the maximum yield (critical S) was about 0.20–0.35% S during August (before flowering) and 0.15–0.20% S during October (after flowering).
21
Bolland, M. D. A., e W. K. Russell. "Changes in chemical properties of 48 intensively grazed, rain-fed dairy paddocks on sandy soils over 11 years of liming in south-western Australia". Soil Research 48, n. 8 (2010): 682. http://dx.doi.org/10.1071/sr09199.
Testo completoAbstract (sommario):
Soil testing was conducted during 1999–2009 to determine lime and fertiliser phosphorus (P), potassium (K), and sulfur (S) requirements of intensively grazed, rain-fed, ryegrass dairy pastures in 48 paddocks on sand to sandy loam soils in the Mediterranean-type climate of south-western Australia. The study demonstrated that tissue testing was required in conjunction with soil testing to confirm decisions based on soil testing, and to assess management decisions for elements not covered by soil testing. Soil testing for pH was reliable for indicating paddocks requiring lime to ameliorate soil acidity, and to monitor progress of liming. Soil P testing proved reliable for indicating when P fertiliser applications were required, with no P being required when soil-test P was above the critical value for that soil, and when no P was applied, tissue testing indicated that P remained adequate for ryegrass production. Soil testing could not be used to determine paddocks requiring fertiliser K and S, because both elements can leach below the root-zone, with rainfall determining the extent of leaching and magnitude of the decrease in pasture production resulting from deficiency, which cannot be predicted. The solution is to apply fertiliser K and S each year, and use tissue testing to improve fertiliser K and S management. Research has shown that, for dairy and other grazing industries in the region, laboratories need measure and report every year soil pH and soil-test P only, together with measuring every 3–5 years the P-buffering index (estimating P sorption of soil), organic carbon content, and electrical conductivity.
22
Holford, I. C. R. "Soil phosphorus: its measurement, and its uptake by plants". Soil Research 35, n. 2 (1997): 227. http://dx.doi.org/10.1071/s96047.
Testo completoAbstract (sommario):
Phosphorus (P) is the most important nutrient element (after nitrogen) limiting agricultural production in most regions of the world. It is extremely chemically reactive, and more than 170 phosphate minerals have been identified. In all its natural forms, including organic forms, P is very stable or insoluble, and only a very small proportion exists in the soil solution at any one time. Plant-available P may be considered in either its quantitative or intensive dimension. The quantity of available P is time-specific and crop-specific, because it is the amount of P that will come into the soil solution and be taken up by the crop during its life cycle. The intensity of available P (availability) is most easily identified with its concentration in the soil solution. The soil property controlling the relationship between the solid phase P and its concentration in solution is known as the buffering capacity. The solid phase P involved in this relationship is only a small proportion of the total P, and is known as labile P. It is usually measured by isotopic exchange, but this exchangeable P component does not include the sparingly soluble compounds that also replenish the soil solution as its concentration is depleted by plant uptake. The buffering capacity is the ability of the soil solution to resist a change in its P concentration as P is removed by plant uptake or added in fertilisers or organic materials. Buffering capacity is synonymous with sorptivity, which is a preferable term in the context of the reactivity of P fertiliser with soil. It is usually measured from an adsorption isotherm. By fitting a suitable equation, such as the Langmuir, the total sorption capacity as well as the sorption strength can be determined. Both parameters are important in understanding P availability in soils. Buffering capacity has a major effect on the uptake of labile P because it is inversely related to the ease of desorption of solid phase P and its diffusion. Available P therefore is a direct function of the quantity of labile P and an inverse function of buffering capacity. This has been demonstrated in plant uptake studies. Similarly, the most effective methods of measuring available P (soil tests) are those which remove a proportion of labile P that is inversely related to buffer capacity. Soil tests which measure the concentration of P in solution actually measure availability rather than available P, and their efficacy on a range of soils will depend on the uniformity of the soils" buffer capacities. The most effective soil test usually consists of an anionic extractant. Acidic lactate or fluoride have been found most effective in New South Wales, on a wide range of soils, except calcareous soils which neutralise the acidic component (usually hydrochloric or acetic acid) of the extractant. Sodium bicarbonate (pH 8 · 5) has been found effective on calcareous soils and is widely used throughout the world. It has proved unreliable on NSW soils, and may need more thorough evaluation on non-calcareous soils in other parts of Australia.
23
Qiu, S., A. J. McComb, R. W. Bell e J. A. Davis. "Nutrient response to soil and litter metabolic activity in a transect across a seasonal wetland". Marine and Freshwater Research 54, n. 3 (2003): 243. http://dx.doi.org/10.1071/mf02156.
Testo completoAbstract (sommario):
Many wetlands in the interdunal depression of coastal sand dunes of the Swan Coastal Plain are surrounded by partially vegetated catchments. Although litter can be an important source of nutrients, little is known about litter related microbial activity in these catchments, especially its role in regulating nutrient concentrations in soils during the wet season. Heterotrophic microbial activity and phosphorus (P) dynamics were monitored before and after the onset of the wet season along transects from a vegetated catchment to the lakebed in Thomsons Lake, south-western Australia. Microbial activity was measured in the field as CO2 efflux (range from 47 to 176 mg CO2 m–2 h–1) and in the laboratory as substrate-induced-respiration (SIR; range from 11 to 133 μg g–1 h–1). Substrate-induced-respiration was positively correlated with soil organic content, and was concentrated in surface soils. In contrast, in the exposed lakebed most microbial biomass was below the surface, in the 10–30 cm depth zone. There were significant changes in nutrient dynamics in response to soil microbial activity. Before rain, P extracted by anion exchange membrane (PAEM) was well correlated with site litter and plant debris (r2 = 0.90, P�<�0.001), suggesting that PAEM in soils was litter-sourced. This relationship was modified during the wet season: there was an overall increase in microbial biomass P (PMB; from average 7.5 μg g–1 to 21.6 μg g–1), and a decrease in PAEM : PMB in surface soils. Along the study transect, the assimilation index PAEM : PMB declined towards the wetland, where soils were more silty and organic, and CO2 production was significantly higher. Our data suggest that heterotrophic microbial activity has a significant role in regulating P flux from catchment litter during the wet season, which would affect the mobility of litter-sourced P from catchment to the wetland.
24
Bolland, M. D. A., e R. F. Brennan. "Comparing the phosphorus requirements of wheat, lupin, and canola". Australian Journal of Agricultural Research 59, n. 11 (2008): 983. http://dx.doi.org/10.1071/ar07430.
Testo completoAbstract (sommario):
Spring wheat (Triticum aestivum L.), lupin (Lupinus angustifolius L.), and canola (Brassica napus L.) are the major crop species grown in rotation on the predominantly sandy soils of south-western Australia. Comparisons among the species for yield responses to applied phosphorus (P), effects of applied P on growth rates of shoots, P response efficiency for shoot and grain production, and the pattern for accumulation of P into shoots during growth and into grain at maturity are rare, or are not known, and were quantified in the glasshouse study reported here. Size and P content (P concentration multiplied by yield) of sown seed were in the order canola < wheat < lupin. Therefore, yield responses to applied P were first observed at ~10 days after sowing (DAS) for canola, ~17 DAS for wheat, and ~60 DAS for lupin. Lupin shoots showed no yield response to applied P at the first harvest at 51 DAS. Otherwise all species showed large yield, P concentration, and P content responses to applied P for all harvests at 51, 78, 87, 101, 121, and 172 DAS. To produce 90% of the maximum grain yield, the relevant data for cropping, lupin required ~67% less P than wheat, canola required ~40% less P than wheat, and canola required ~75% more P than lupin. Growth rates, and P response efficiency, were generally largest for canola, followed by wheat, then lupin. For shoots, P accumulation was in the order lupin > wheat > canola at 51 DAS, canola > wheat > lupin at 78 and 87 DAS, canola > wheat = lupin at 101 DAS, and all 3 species were about similar at 121 DAS. For accumulation of P into shoots plus grain at maturity (172 DAS) the order was canola > lupin > wheat, and for grain only was canola > wheat = lupin.
25
Harries, Martin, Ken C. Flower e Craig A. Scanlan. "Sustainability of nutrient management in grain production systems of south-west Australia". Crop and Pasture Science 72, n. 3 (2021): 197. http://dx.doi.org/10.1071/cp20403.
Testo completoAbstract (sommario):
Balancing nutrient inputs and exports is essential to maintaining soil fertility in rainfed crop and pasture farming systems. Soil nutrient balances of land used for crop and pasture production in the south-west of Western Australia were assessed through survey data comprising biophysical measurements and farm management records (2010–15) across 184 fields spanning 14 Mha. Key findings were that nitrogen (N) inputs via fertiliser or biological N2 fixation in 60% of fields, and potassium (K) inputs in 90% of fields, were inadequate to balance exports despite increases in fertiliser usage and adjustments to fertiliser inputs based on rotations. Phosphorus (P) and sulfur (S) balances were positive in most fields, with only 5% returning losses >5 kg P or 7 kg S/ha. Within each of the three agroecological zones of the survey, fields that had two legume crops (or pastures) in 5 years (i.e. 40% legumes) maintained a positive N balance. At the mean legume inclusion rate observed of 20% a positive partial N budget was still observed for the Northern Agricultural Region (NAR) of 2.8 kg N/ha.year, whereas balances were negative within the Central Agricultural Region (CAR) by 7.0 kg N/ha.year, and the Southern Agricultural Region (SAR) by 15.5 kg N/ha.year. Hence, N budgets in the CAR and SAR were negative by the amount of N removed in ~0.5 t wheat grain, and continuation of current practices in CAR and SAR fields will lead to declining soil fertility. Maintenance of N in the NAR was achieved by using amounts of fertiliser N similar to other regions while harvesting less grain. The ratio of fertiliser N to legume-fixed N added to the soil in the NAR was twice that of the other regions. Across all regions, the ratio of fertiliser N to legume-fixed N added to the soil averaged ~4.0:1, a major change from earlier estimates in this region of 1:20 under ley farming systems. The low contribution of legume N was due to the decline in legume inclusion rate (now 20%), the low legume content in pastures, particularly in the NAR, and improved harvest index of lupin (Lupinus angustifolius), the most frequently grown grain legume species. Further quantifications of the effects of changing farming systems on nutrient balances are required to assess the balances more accurately, thereby ensuring that soil fertility is maintained, especially because systems have altered towards more intensive cropping with reduced legume production.
26
Shane, Michael W., e John S. Pate. "Survival strategies of the root tuberous geophyte Chamaescilla corymbosa in a Mediterranean-climate rock-outcrop environment". Australian Journal of Botany 63, n. 6 (2015): 497. http://dx.doi.org/10.1071/bt14220.
Testo completoAbstract (sommario):
This field-based study aimed to identify adaptive traits that operate interactively and sequentially towards survival and growth of the perennial geophyte Chamaescilla corymbosa when inhabiting shallow soils on exposed granite outcrops in south-western Australia. During an annual cycle of growth and dormancy, we measured changes in biomass partitioning, mineral nutrient concentrations in root tubers, leaves, roots and seed. Anatomical and histochemical analyses of fleshy-root tubers included identification and quantification of key carbohydrate and free amino acid reserves. During the course of the growing season, developing root tubers accumulated fructans, raffinose and sucrose to maximal concentration at the onset of summer dormancy. Water content of root tubers was similar in summer or winter (79% or 84%, respectively). Accumulation of carbohydrates and development of a lignified and suberised hypodermis are likely to protect aestivating root tubers from desiccation during hot, dry summer. Assimilates and mineral resources acquired in the winter growing season were shown to be preferentially allocated for new tuber production, as opposed to sexual reproduction. Accumulation of key nitrogenous solutes and phosphorus in root tubers before dormancy suggested an adaptive response of the species to soils with inherently low concentrations of available nutrients. Experiments on field-grown populations showed the species to be responsive to delayed commencement of seasonal growth by reducing size and number of root tubers; however, plants still survived until the next growing season. Results are discussed against previous studies of other geophytes on rock outcrops and other similarly testing environments.
27
Hoppo, S. D., D. E. Elliott e D. J. Reuter. "Plant tests for diagnosing phosphorus deficiency in barley (Hordeum vulgare L.)". Australian Journal of Experimental Agriculture 39, n. 7 (1999): 857. http://dx.doi.org/10.1071/ea99029.
Testo completoAbstract (sommario):
Summary. Six field experiments were conducted in the Murraylands and Mid North regions of South Australia between 1986 and 1988 to develop plant tests for diagnosing the phosphorus status of barley. The effects of applied phosphorus level on total phosphorus concentrations in youngest emerged leaf blades or whole shoots, and on shoot yield, were examined and critical ranges were established during vegetative growth. Experiments were conducted on a range of soil phosphorus levels with several methods of phosphorus placement and 2 barley cultivars. During early tillering, shoot yield and phosphorus concentrations in youngest emerged leaf blades and whole shoots were increased more by drilling phosphorus fertiliser with the seed (banded) than by spreading the same phosphorus rate over the soil surface and partially incorporating the fertiliser while sowing (broadcast). However, these methods of phosphorus placement did not affect diagnostic relationships between relative shoot yield and phosphorus concentrations in youngest emerged leaf blades and, as a result, critical total phosphorus concentrations were similar for both methods of applying phosphorus fertiliser. Estimated critical total phosphorus concentrations for both Schooner and Galleon barley were similar at each sampling time when allowances were made for minor differences in growth stages between the cultivars; even though phosphorus concentrations in youngest emerged leaf blades and whole shoots were higher in Schooner than in Galleon at adequate phosphorus supply. Between Zadoks scale 13.5 and 16.5 there was a linear decline in critical total phosphorus concentration in youngest emerged leaf blades with increasing plant age. A more variable, but steeper, decline was found for critical total phosphorus concentration in whole shoots. Critical ranges are proposed for total phosphorus concentrations in youngest emerged leaf blades and whole shoots of barley. The decline in critical total phosphorus concentration in youngest emerged leaf blades with advancing plant age was mainly caused by a higher functional requirement for phosphorus at early stages of growth and by increasing dry weight, cellulose and lignin content of youngest emerged leaf blades as plants age. Changes in the spatial distribution of applied phosphorus in relation to root growth did not seem to be important.
28
Brennan, R. F., e M. D. A. Bolland. "Soil properties as predictors of yield response of clover (Trifolium subterraneum L.) to added P in soils of varying P sorption capacity". Soil Research 41, n. 4 (2003): 653. http://dx.doi.org/10.1071/sr02108.
Testo completoAbstract (sommario):
Thirty-five unfertilised soils collected in south-western Australia were used to measure the effect of soil properties on (i) shoot yield responses of 50-day-old clover (Trifolium subterraneum L. cv. Nungarin) plants to applied phosphorus (P), and (ii) extractability of bicarbonate soil test P (slope of the linear relationship between Colwell P and the amount of P applied). Data for the relationship between shoot yield and the amount of P applied were fitted to a rescaled Mitscherlich equation to calculate the amount of P required to produce 50% and 90% of the maximum yield (P50% and P90%) and determine the curvature (c) and n coefficients of the equation. When the value of n is 1.00, the response curve is exponential, and as the value of n increases above 1.00 the response curve becomes more sigmoidal. The c, n, P50%, P90%, and extractability values were related to properties of the 35 soils.There was a significant (P < 0.05) trend for the values of c and extractability to decrease as the capacity of the soil to sorb P increased. Consequently, as the soil sorbed more P, the trend was that (1) more P needed to be applied to produce the same yield, so both P50% and P90% tended to significantly (P < 0.05) increase; (2) shoot yield responses to applied P became more sigmoidal so the value of the n coefficient tended to significantly (P < 0.05) increase; (3) more P needed to be applied to a soil to produce the same soil test P value; and (4) larger soil test P values were needed to produce the same yield. No single soil property adequately predicted P50%, P90%, extractability, c, or n. Stepwise multiple regression indicated that (1) clay content and P buffer capacity (PBC) of soil together accounted for 48% of the variation in P50%, 56% of the variation in P90%, and 52% of the variation in c; (2) PBC and soil pH together accounted for 17% of the variation in n; and (3) PBC, percentage clay and percentage organic carbon content of soil together accounted for 68% of the variation in extractability.
29
Hackney, B. F., J. Jenkins, J. Powells, C. E. Edwards, S. De Meyer, J. G. Howieson, R. J. Yates e S. E. Orgill. "Soil acidity and nutrient deficiency cause poor legume nodulation in the permanent pasture and mixed farming zones of south-eastern Australia". Crop and Pasture Science 70, n. 12 (2019): 1128. http://dx.doi.org/10.1071/cp19039.
Testo completoAbstract (sommario):
Pasture legumes must be adequately and effectively nodulated in order to reach nitrogen-fixation targets. Of 225 pasture paddocks sampled across the Central Tablelands, Central West, Monaro and Riverina regions of New South Wales, 93% had inadequate legume nodulation. Legume content was significantly higher in the mixed faming zone (>50%, Central West and Riverina) than the permanent pasture zone (26%, Central Tablelands; 28% Monaro). Available phosphorus (P) was below critical levels in 40% of paddocks sampled and sulfur (S) in 73% of paddocks; >35% of all paddocks had soil pHCa <5.0. Deficiency of P was more prevalent in the Central Tablelands (63% of paddocks), whereas S deficiency occurred more frequently in the Central West (95% of paddocks). Legume nodule scores were associated with host legume species, soil pH, available P and/or S, and cation exchange capacity, which collectively accounted for 73% of variation. For Trifolium spp., at soil pHCa >5.55, nodulation was predicted to be near adequate (score 3.95, where adequate = 4). At pHCa <5.55, higher available S resulted in a higher nodulation score (2.42) than in paddocks where S was deficient (score 0–1.97). These results suggest that improving the capacity of legumes to supply nitrogen should focus on addressing soil acidity and plant nutrition, specifically P and S.
30
Norton, Mark R., Denys L. Garden, Beverley A. Orchard, Philip Armstrong e Trent Brassil. "Effects of lime, phosphorus and stocking rate on an extensively managed permanent pasture: botanical composition and groundcover". Crop and Pasture Science 71, n. 7 (2020): 700. http://dx.doi.org/10.1071/cp20135.
Testo completoAbstract (sommario):
Low phosphorus (P) constrains productivity of many of the permanent pastures of south-eastern Australia where wool and meat production are important. Whereas the need for fertilisation with P is indisputable for many soils, the benefits of liming to ameliorate soil acidification are not always clear in terms of forage production or quality. This experiment, by measuring botanical composition and groundcover over 10 years, aimed to address the issue of forage composition and groundcover. Merino wethers were continuously grazed on a permanent pasture under two stocking rates (low and high) following treatments with three rates of surface-applied lime and two rates of P. The lime rates were: nil, and sufficient to raise the pHCaCl2 of the 0–10 cm soil layer to 5.0 and to 5.5. Phosphorus was added as two rates of single superphosphate: 125 kg ha–1 every 2–3 years, and 250 kg ha–1 every year. Two hypotheses were proposed: (i) as lime application rate increased, it would lead to the pasture swards having a higher percentage of species favourable for grazing animal production, and a higher level of sward groundcover would be maintained; and (ii) legume presence would be favoured by a higher level of applied P over the long term. The Millennium Drought (1997–2008), which coincided with this experiment (1998–2008), tended to mask or reduce lime effects; nevertheless, the higher legume content in the sward, as well as the superior groundcover found in the high lime–high P treatments at various times throughout the experiment and at its completion compared with the nil-lime control, indicated positive forage effects of lime application. Moreover, by the termination of the experiment in 2008, groundcover generally tended to be lower under nil lime than in treatments that had received lime. The higher proportion of legume in the sward was closely linked to greater applied P, although this did not occur at the low stocking rate in the absence of lime. By contrast, similar high P–low stocking rate treatments but with applied lime had the highest clover contents. It is proposed that the poor persistence of the treatment without lime may be due to a combination of poor legume seedset, because of excessive competition from accompanying grasses, and aluminium toxicity adversely affecting legume growth.
31
You, M. P., I. T. Riley, K. Sivasithamparam e M. J. Barbetti. "Relationship of rainfall, cultural practices, soil and plant nutrients, and seedling survival with root disease and parasitic nematode numbers in annual Medicago spp. Pastures". Australian Journal of Agricultural Research 50, n. 6 (1999): 977. http://dx.doi.org/10.1071/ar98175.
Testo completoAbstract (sommario):
Surveys were conducted for annual Medicago spp. (medic) pastures in the grain belt of south-west Western Australia during spring 1996 and winter–spring 1997 to determine the relationship of rainfall, cultural practices, soil and plant nutrients, and seedling survival with severity of root disease and numbers of parasitic nematodes. Medic pasture was sampled on 116 farms. Most pastures consisted of a single medic variety, viz. Serena, Santiago, Cyprus, or Caliph, whereas about 33% of sites had mixed varieties. Regression analyses showed that high rainfall and application of phosphorus fertilisers were correlated with increased severity of rot in medic tap roots. Crop history and medic variety were not related to the level of root rot. Numbers of Pratylenchusin medic roots were not correlated with the level of tap or lateral root rot, medic variety, rainfall, or with the application of insecticide, fertilisers, or herbicides. Soil with relatively high levels of P, NO3-, or Fe was associated with an increased level of tap root rot. Soils with high pH were associated with reduced tap root rot. Soils with relatively high K were related to severe lateral root rot, whereas relatively high levels of P in soil were associated with reduced lateral root rot. Plants with high levels of tap root rot showed low levels of Mg, whilst low levels of Ca and NO3– in tissues were related to high levels of lateral root rot. High levels of tap root rot were associated with relatively high levels of total N, K, and S, Cu, Zn, Mn, and NO3- in plant tissues. Plants with relatively high levels of lateral root rot had relatively high levels of Cu in shoots. Of the 116 annual Medicago pastures sampled, only 1% had adequate Mg content and only 19% had adequate Ca content. However, 83% had higher than adequate levels of Cu, 70% had higher than adequate levels of Mn, and all samples showed more than adequate levels of chloride. Experimental sites of M. polymorpha cv. Serena at 6 farms showed that the percentage survival rate of seedlings was negatively correlated with the severity of tap and lateral root rot in the previous year. These results indicate that in the farms surveyed there is a serious threat to annual medic pastures from root rot fungi. The severity of the disease was partly determined by soil conditions and cultural practices.
32
Berger, J. D., K. H. M. Siddique e S. P. Loss. "Cool season grain legumes for Mediterranean environments: species × environment interaction in seed quality traits and anti-nutritional factors in the genus Vicia". Australian Journal of Agricultural Research 50, n. 3 (1999): 389. http://dx.doi.org/10.1071/a98098.
Testo completoAbstract (sommario):
Seed size and protein, sulfur (S), total phenolics, condensed tannins, and proteinase inhibitor concentrations were measured in 4 Vicia species (V. faba, V. sativa, V. ervilia, V. narbonensis) grown at up to 30 locations in the south-west of Western Australia. There was a species × environment interaction for all seed traits, and this was reflected in the relationships with environmental parameters and other seed traits within each species. For V. faba, it was difficult to account for the production of seed quality traits or antinutritional factors on the basis of descriptive environmental parameters such as climate or edaphic characteristics. The remaining species were more responsive to environmental factors measured throughout the study. Seed size was negatively associated with soil salinity in V. narbonensis and V. ervilia. Seed protein content was positively correlated with soil total nitrogen (N) and phosphorus (P) in V. sativa and V. ervilia, and also with electrical conductivity, pH, and exchangeable cations in V. ervilia. The S content of V. narbonensis seeds increased with increasing soil S availability, while the opposite occurred in V. ervilia and V. sativa. Total phenolics were positively associated with total N and P in V. sativa, and negatively correlated with soil clay content, S, and salinity in V. ervilia. Proteinase inhibitors in V. sativa were positively associated with soil salinity, while the opposite was the case in V. ervilia. Proteinase inhibitors in V. ervilia were also negatively correlated with pH, clay content, total N, and exchangeable cations, whereas the total N and exchangeable cations were associated with increasing proteinase inhibitors in V. narbonensis. These complex and contrasting relationships between antinutritional factors and environmental parameters suggest that the carbon: nutrient balance hypothesis, the pre-eminent paradigm used to predict plant resource allocation to N and C based defence, may not be applicable to the seeds of legumes. The agricultural significance of the species ´ environment interaction above depends on the seed characteristic in question. Increased S uptake by V. narbonensis relative to V. ervilia and V. sativa may advantage this species as a fodder crop, given that these species are targeted at alkaline, fine-textured soils where soil S availability is likely to be relatively high. However, in the seed of V. narbonensis and V. sativa, fluctuating concentrations of polyphenolics and condensed tannins occasionally reach the relatively high levels recorded in V. faba, and other anti-nutritional factors not withstanding, this may limit their palatability to monogastrics.
33
Weatherley, AJ, MDA Bolland e RJ Gilkes. "A comparison of values for initial and residual effectiveness of rock phosphates measured in pot and field experiments". Australian Journal of Experimental Agriculture 28, n. 6 (1988): 753. http://dx.doi.org/10.1071/ea9880753.
Testo completoAbstract (sommario):
The effectiveness of Calciphos (500�C calcined calcium-aluminium C-grade rock phosphate from Christmas Island), Queensland rock phosphate (low carbonate substituted apatite, from Duchess deposit, Northern Queensland [QRP]), and granular North Carolina rock phosphate (highly carbonate substituted apatite from U.S.A. [NCRP]) were compared with the effectiveness of monocalcium phosphate (MCP) fertilisers in pot and field experiments. Three different lateritic soils from south-western Australia and different plant species were used. In the pot experiment, the effectiveness of the fertilisers was measured relative to freshly applied MCP for 5 successive crops. Subterranean clover, oats, triticale and barley were grown for about 1 month before harvesting. In the field experiment, the same plants were grown, and the effectiveness of the fertilisers was measured relative to freshly applied triple superphosphate for 3 successive years. On a dry matter yield basis, the effects of freshly applied rock phosphate dressings measured in the pot experiment were in a similar range to those measured in the field experiment for the same soil types, and the same plant species, indicating that pot trials can substitute for field trials for the evaluation of the initial effectiveness of fertilisers. However, the residual effectiveness values for both MCP and the RPs were generally much lower for the pot experiment, indicating that pot experiments cannot replace long-term field experiments for the reliable measurement of residual effectiveness of fertilisers. For the pot experiment, the relative effectiveness values of freshly applied NCRP and Calciphos for all soils were 0.2-0.3 and 0.1-0.2 respectively. The corresponding values for the field experiment were 0.1-0.3 for NCRP and 0.1 for Calciphos. For the pot experiment, the relative effectiveness of freshly applied QRP on all soils ranged from 0.03 to 0.1, compared with from 0.1 to 0.3 for the field experiment. The relative effectiveness of all fertilisers declined markedly with successive crops (i.e. crops 2-5) in the pot experiment, whereas in the field experiment the relative effectiveness of QRP and NCRP showed no systematic change for the 3-years of the experiment. For the pot experiment the relative effectiveness of residual MCP decreased to about 0.3, 0.2 and 0.1, compared with 0.5, 0.2 and 0.5 for the field experiment for West Dale, South Bodallin and Gibson soils, respectively. For the pot experiment and for all soils the residual relative effectiveness of NCRP and Calciphos was about 0.01- 0.04, compared with 0.003-0.02 for QRP. For the field experiment the corresponding values were 0.05-0.2 for NCRP and Calciphos and 0.01-0.1 for QRP. For both the pot and the field experiments the relationship between yield and phosphorus content was sometimes dependent on fertiliser type.
34
Berger, J. D., K. H. M. Siddique e S. P. Loss. "Cool season grain legumes for Mediterranean environments: the effect of environment on non-protein amino acids in Vicia and Lathyrus species". Australian Journal of Agricultural Research 50, n. 3 (1999): 403. http://dx.doi.org/10.1071/a98097.
Testo completoAbstract (sommario):
Variation among a range of potentially deleterious non-protein amino acids found in the seeds of the genera Vicia and Lathyrus was determined by growing species at up to 31 sites covering the range of environments experienced in the cropping region of south-west Australia. γ-Glutamyl-S-ethenyl cysteine (GEC) concentrations in V. narbonensis were correlated to seed sulfur levels (r = 0.95, P < 0.001) in 1 of 2 genotypes, and shown to increase under conditions of increasing soil sulfur availability, pH, clay content, cation exchange capacity, concentration of exchangeable cations, and salinity. To capitalise on the agricultural potential of this species we recommend the selection of genotypes that break the linkage between GEC and seed sulfur. In Lathyrus species the degree of variation of β-N-oxalyl-L-α, β-diaminopropionic acid (ODAP) in the seed appears to be proportional to the species mean ODAP concentration; L. ochrus was more responsive than L. sativus, which was in turn more responsive than L. cicera. Seed ODAP concentrations in L. ochrus and L. sativus were positively correlated with soil phosphorus, and negatively correlated with clay content and salinity, and may constrain the species potential for human and animal consumption. In V. ervilia seed, canavanine concentrations were extremely variable in the field (0.01–0.17%), but are unlikely to reduce the stockfeed potential of this species for either monogastrics or ruminants.
35
Anderson, Geoffrey C., Shahab Pathan, James Easton, David J. M. Hall e Rajesh Sharma. "Short- and Long-Term Effects of Lime and Gypsum Applications on Acid Soils in a Water-Limited Environment: 1. Grain Yield Response and Nutrient Concentration". Agronomy 10, n. 8 (18 agosto 2020): 1213. http://dx.doi.org/10.3390/agronomy10081213.
Testo completoAbstract (sommario):
Surface (0–10 cm) and subsoil (soil layers below 10 cm) acidity and resulting aluminum (Al) toxicity reduce crop grain yields. In South Western Australia (SWA), these constraints affect 14.2 million hectares or 53% of the agricultural area. Both lime (L, CaCO3) and gypsum (G, CaSO4) application can decrease the toxic effect of Al, leading to an increase in crop grain yields. Within the region, it is unclear if G alone or the combined use of L and G has a role in alleviating soil acidity in SWA, due to low sulfate S (SO4–S) sorption properties of the soil. We present results from three experiments located in the eastern wheatbelt of SWA, which examined the short-term (ST, 2 growing seasons), medium-term (MT, 3 growing seasons), and long-term (LT, 7 growing seasons over 10 years) effects of L and G on grain yield and plant nutrient concentrations. Despite the rapid leaching of SO4–S and no self-liming impact, it was profitable to apply G, due to the significant ST grain yield responses. The grain yield response to G developed even following relatively dry years, but declined over time due to SO4–S leaching. At the LT experimental site had received no previous L application, whereas, at the ST and MT sites, L had been applied by the grower over the previous 5–10 years. For the LT site, the most profitable treatment for wheat (Triticum aestivum L.) grain yield, was the combined application of 4 t L ha−1 with 2 t G ha−1. At this site, the 0–10 cm soil pHCaCl2 was 4.6, and AlCaCl2 was greater than 2.5 mg kg−1 in the 10–30 cm soil layer. In contrast, at the ST and MT sites, the pHCaCl2 of 0–10 cm soil layer was ≥5.5; it was only profitable to apply G to the MT site where the soil compaction constraint had been removed by deep ripping. The use of L increases soil pHCaCl2, resulting in the improved availability of anions, phosphorus (P) in the LT and molybdenum (Mo) at all sampling times, but reduced availability of cations zinc (Zn) in the LT and manganese (Mn) at all sampling. The application of G reduced Mo concentrations, due to the high SO4–S content of the soil.
36
Cox, J. W., C. A. Kirkby, D. J. Chittleborough, L. J. Smythe e N. K. Fleming. "Mobility of phosphorus through intact soil cores collected from the Adelaide Hills, South Australia". Soil Research 38, n. 5 (2000): 973. http://dx.doi.org/10.1071/sr99125.
Testo completoAbstract (sommario):
Intact cores were collected from a variety of soils in the Adelaide Hills, South Australia, and tested for phosphorus retention and mobility (P in drainage) under various rainfall intensities (5, 25, and 50 mm/h). Phosphorus mobility was high in soils with significant macropore structure. However, all soils exhibited some degree of preferential flow of P, including the heavy-textured soils with high P adsorption that were not P saturated. A phosphorus adsorption index based only on the chemical properties of the soil did not accurately predict the mobility of P through soils with macroporosity. A phosphorus mobility index was developed encompassing both soil chemical and physical parameters. Results showed the sandy soils, and the loams over clays with high macroporosity that are located in the more elevated parts of the Adelaide hills, are most susceptible to P leaching. Management to reduce P loss to groundwater, streams, or surface water storages must aim to increase the residence time of P within soils and thereby allow mineral and organic fractions time to sorb P. Phosphorus loss through wet soils was significantly less than P loss through dry soils with high macroporosity. Application of P fertiliser to soils with high macroporosity may need to be delayed until later in the growing season than is currently practised.
37
Doolette, Ashlea L., Ronald J. Smernik e Timothy I. McLaren. "The composition of organic phosphorus in soils of the Snowy Mountains region of south-eastern Australia". Soil Research 55, n. 1 (2017): 10. http://dx.doi.org/10.1071/sr16058.
Testo completoAbstract (sommario):
Few studies have considered the influence of climate on organic phosphorus (P) speciation in soils. We used sodium hydroxide–ethylenediaminetetra-acetic acid (NaOH–EDTA) soil extractions and solution 31P nuclear magnetic resonance spectroscopy to investigate the soil P composition of five alpine and sub-alpine soils. The aim was to compare the P speciation of this set of soils with those of soils typically reported in the literature from other cold and wet locations, as well as those of other Australian soils from warmer and drier environments. For all alpine and sub-alpine soils, the majority of P detected was in an organic form (54–66% of total NaOH–EDTA extractable P). Phosphomonoesters comprised the largest pool of extractable organic P (83–100%) with prominent peaks assigned to myo- and scyllo-inositol hexakisphosphate (IP6), although trace amounts of the neo- and d-chiro-IP6 stereoisomers were also present. Phosphonates were identified in the soils from the coldest and wettest locations; α- and β-glycerophosphate and mononucleotides were minor components of organic P in all soils. The composition of organic P in these soils contrasts with that reported previously for Australian soils from warm, dry environments where inositol phosphate (IP6) peaks were less dominant or absent and humic-P and α- and β-glycerophosphate were proportionally larger components of organic P. Instead, the soil organic P composition exhibited similarities to soils from other cold, wet environments. This provides preliminary evidence that climate is a key driver in the variation of organic P speciation in soils.
38
Bolland, M. D. A., M. W. Sweetingham e R. J. Jarvis. "Effect of applied phosphorus on the growth of Lupinus luteus, L. angustifolius and L. albus in acidic soils in the south-west of Western Australia". Australian Journal of Experimental Agriculture 40, n. 1 (2000): 79. http://dx.doi.org/10.1071/ea99065.
Testo completoAbstract (sommario):
Phosphorus is the major nutrient element deficiency of grain legumes in the south-west of Western Australia. Lupinus angustifolius is the major grain legume grown on the acidic soils in Western Australia. However, L. luteus and L. albus are being researched as possible alternatives because of tolerance to diseases and specific soil type adaptation. The fertiliser phosphorus requirements of L. luteus and L. albus in acidic soils of Western Australia are not well known. By contrast, there is much information on the phosphorus requirements of L. angustifolius in these soils where placement of fertiliser phosphorus has been found to be important. Three field experiments were undertaken on different acidic soils in Western Australia (sand, sandy loam, and loamy sand) to compare how L. luteus cv. Teo and L. angustifolius cv. Merrit use fertiliser phosphorus, applied by different methods as superphosphate. Lupinus albus cv. Kiev Mutant, which is not adapted to the sandier soils, was included at the loamy sand site. In 2 experiments on the loamy soils, the phosphorus was either placed with the seed (drilled) or 8 cm below the seed while sowing seed at 5 cm (banded). In the experiment on sand, the phosphorus was either spread over the soil surface immediately in front of the seeding tines (topdressed) or banded below the seed. Compared with L. angustifolius: (i) for the 2 loamy soils, L. luteus used phosphorus more effectively for producing dried shoots, but was less effective at using phosphorus for producing seed (grain); (ii) for the loamy sand, L. albus was less effective at using the phosphorus for producing dried shoots and grain, except it was about equally effective for producing grain when the phosphorus was banded below the seed. For the sandy soil, L. luteus produced no grain yield response whereas L. angustifolius showed an about 20% yield response to the added phosphorus, and both methods of application were about equally effective. Phosphorus banded below the seed was more effective than phosphorus drilled with the seed for producing dried shoots and grain of L. albus on the loamy sand and for grain only of L. luteus on the sandy loam. Both methods of phosphorus application were about equally effective for producing dried shoots and grain of L. angustifolius and grain of L. luteus on the loamy sand. Fertiliser drilled with the seed was more effective than banded fertiliser for producing dried shoots and grain of L. angustifolius on the sandy loam and dried shoots of L. luteus on the loamy sand and sandy loam. The concentration of phosphorus in grain of L. luteus was consistently about double that found in grain of L. angustifolius. The concentration of manganese in dried shoots of L. albus was 3–5 times higher than in the other 2 species.
39
Chittleborough, D. J., J. W. Cox e D. P. Stevens. "Pathways of phosphorus, nitrogen, and carbon movement over and through texturally differentiated soils, South Australia". Soil Research 37, n. 4 (1999): 679. http://dx.doi.org/10.1071/sr98082.
Testo completoAbstract (sommario):
One method for preventing the degradation of water supplies through contamination with phosphorus (P), nitrate (NO3), and dissolved organic carbon (DOC) is to restrict movement of these contaminants from the catchment into water bodies. The purpose of the study was to quantify and characterise the proportion of NO3, P, and DOC moving from duplex soils by overland flow and through-flow on a sub-catchment scale, and to characterise soil properties that influence their movement. Two sites in the Adelaide Hills (South Australia) with contrasting duplex soils were instrumented to collect overland flow and through-flow from the soils A and B horizon. Each site contained 2 sub-catchments in close proximity. Sub-catchments were well defined by the natural topography sloping from hillcrest to a stream headwater. Soil type, especially the degree of texture contrast, the macroporosity, and the proportion of clay in the B horizon, had a large influence on the pathways of water, and therefore P, DOC, and NO3 movement. Environmentally significant concentrations of P (>0�1 mg/L) and NO3-N (>0�5 mg/L) moved overland and through these soils in 1997. High DOC loads (25 mg/L), which would also impact on water treatment costs, moved through some soils. Significant loading of P moved through and over soils in both dissolved (0�5 mg/L) and particulate (0�3 mg/L) forms. Consequently, through-flow cannot be ignored as a contributor to P in streams and both dissolved and particulate P must be measured under these conditions to define the full impact of P. The findings from this research have implications for research on catchment management to restrict DOC and nutrient movement into waterways.
40
Henry, P. C., e Marie F. Smith. "The relationship between the phosphorus requirement and Ambic 1 phosphorus content of selected South African soils". South African Journal of Plant and Soil 22, n. 3 (gennaio 2005): 163–70. http://dx.doi.org/10.1080/02571862.2005.10634701.
Testo completo
41
Valentine, S., P. Lewis, R. T. Cowan e J. DeFaveri. "The effects of high stocking rates on milk production from dryland and irrigated Mediterranean pastures". Animal Production Science 49, n. 2 (2009): 100. http://dx.doi.org/10.1071/ea07071.
Testo completoAbstract (sommario):
An experiment using herds of ~20 cows (farmlets) assessed the effects of high stocking rates on production and profitability of feeding systems based on dryland and irrigated perennial ryegrass-based pastures in a Mediterranean environment in South Australia over 4 years. A target level of milk production of 7000 L/cow.year was set, based on predicted intakes of 2.7 t DM/cow.year as concentrates, pasture intakes from 1.5 to 2.7 t/cow.year and purchased fodder. In years 1 and 2, up to 1.5 t DM/cow.year of purchased fodder was used and in years 3 and 4 the amounts were increased if necessary to enable levels of milk production per cow to be maintained at target levels. Cows in dryland farmlets calved in March to May inclusive and were stocked at 2.5, 2.9, 3.3, 3.6 and 4.1 cows/ha, while those in irrigated farmlets calved in August to October inclusive and were stocked at 4.1, 5.2, 6.3 and 7.4 cows/ha. In the first 2 years, when inputs of purchased fodder were limited, milk production per cow was reduced with higher stocking rates (P < 0.01), but in years 3 and 4 there were no differences. Mean production was 7149 kg/cow.year in years 1 and 2, and 8162 kg/cow.year in years 3 and 4. Production per hectare was very closely related to stocking rate in all years (P < 0.01), increasing from 18 to 34 t milk/ha.year for dryland farmlets (1300 to 2200 kg milk solids/ha) and from 30 to 60 t milk/ha.year for irrigated farmlets (2200 to 4100 kg milk solids/ha). Almost all of these increases were attributed to the increases in grain and purchased fodder inputs associated with the increases in stocking rate. Net pasture accumulation rates and pasture harvest were generally not altered with stocking rate, though as stocking rate increased there was a change to more of the pasture being grazed and less conserved in both dryland and irrigated farmlets. Total pasture harvest averaged ~8 and 14 t DM/ha.year for dryland and irrigated pastures, respectively. An exception was at the highest stocking rate under irrigation, where pugging during winter was associated with a 14% reduction in annual pasture growth. There were several indications that these high stocking rates may not be sustainable without substantial changes in management practice. There were large and positive nutrient balances and associated increases in soil mineral content (P < 0.01), especially for phosphorus and nitrate nitrogen, with both stocking rate and succeeding years. Levels under irrigation were considerably higher (up to 90 and 240 mg/kg of soil for nitrate nitrogen and phosphorus, respectively) than under dryland pastures (60 and 140 mg/kg, respectively). Soil organic carbon levels did not change with stocking rate, indicating a high level of utilisation of forage grown. Weed ingress was also high (to 22% DM) in all treatments and especially in heavily stocked irrigated pastures during winter. It was concluded the higher stocking rates used exceeded those that are feasible for Mediterranean pastures in this environment and upper levels of stocking are suggested to be 2.5 cows/ha for dryland pastures and 5.2 cows/ha for irrigated pastures. To sustain these suggested stocking rates will require further development of management practices to avoid large increases in soil minerals and weed invasion of pastures.
42
Hayes, Patrick E., Peta L. Clode, Caio Guilherme Pereira e Hans Lambers. "Calcium modulates leaf cell-specific phosphorus allocation in Proteaceae from south-western Australia". Journal of Experimental Botany 70, n. 15 (9 aprile 2019): 3995–4009. http://dx.doi.org/10.1093/jxb/erz156.
Testo completoAbstract (sommario):
Abstract Over 650 Proteaceae occur in south-western Australia, contributing to the region’s exceptionally high biodiversity. Most Proteaceae occur exclusively on severely nutrient-impoverished, acidic soils (calcifuge), whilst only few also occur on young, calcareous soils (soil-indifferent), higher in calcium (Ca) and phosphorus (P). The calcifuge habit of Proteaceae is explained by Ca-enhanced P toxicity, putatively linked to the leaf cell-specific allocation of Ca and P. Separation of these elements is essential to avoid the deleterious precipitation of Ca-phosphate. We used quantitative X-ray microanalysis to determine leaf cell-specific nutrient concentrations of two calcifuge and two soil-indifferent Proteaceae grown in hydroponics at a range of Ca and P concentrations. Calcium enhanced the preferential allocation of P to palisade mesophyll (PM) cells under high P conditions, without a significant change in whole leaf [P]. Calcifuges showed a greater PM [P] compared with soil-indifferent species, corresponding to their greater sensitivity. This study advances our mechanistic understanding of Ca-enhanced P toxicity, supporting the proposed model, and demonstrating its role in the calcifuge distribution of Proteaceae. This furthers our understanding of nutrient interactions at the cellular level and highlights its importance to plant functioning.
43
Holland, Jonathan E., e Asim Biswas. "Predicting the mobile water content of vineyard soils in New South Wales, Australia". Agricultural Water Management 148 (gennaio 2015): 34–42. http://dx.doi.org/10.1016/j.agwat.2014.09.018.
Testo completo
44
Mclaughlin, MJ, TG Baker, TR James e JA Rundle. "Distribution and forms of phosphorus and aluminum in acidic topsoils under pastures in south-eastern Australia". Soil Research 28, n. 3 (1990): 371. http://dx.doi.org/10.1071/sr9900371.
Testo completoAbstract (sommario):
The vertical distributions of pH, and forms of phosphorus (P) and aluminium (Al) in acidic topsoils (0-100 mm depth) under pastures were examined at 15 sites in New South Wales and Victoria. The soils were characterized by shallow surface strata of moderate pH, high P and low Al concentrations overlying more acidic, P-deficient and Al-rich subsurface strata. Significant amounts (35-65%) of the total P in acidic pasture topsoils were present in organic forms (Po). Some 20-40% of this Po was extractable using 0.5 M NaHCO3, and is regarded as easily mineralizable and a potential source of P for plant uptake. Substantial amounts of Al were present in crystalline and non-crystalline oxides (2000- 6000 mg kg-1) and complexed to organic matter (up to 400 mg kg-1). The amount of aluminium extracted using reagents commonly accepted to indicate Al toxicity in soils (1 M KCl and 0.01 M CaCl2) was not related to the amounts of those Al forms (extracted by ammonium oxalate, sodium citrate-dithionite) typically identified in pedological and mineralogical studies. Sampling and analysis of soils for determining P fertilizer requirements and diagnosing acidity and related problems (e.g. Al toxicity, Ca deficiency) should take into account the vertical heterogeneity in soil properties in the top 100 mm of the profile.
45
Banu, Nargis A., Balwant Singh e Les Copeland. "Microbial biomass and microbial biodiversity in some soils from New South Wales, Australia". Soil Research 42, n. 7 (2004): 777. http://dx.doi.org/10.1071/sr03132.
Testo completoAbstract (sommario):
Eight surface soils (0–15 cm) including 1 Ferrosol, 2 Tenosols, 2 Kurosols, 1 Sodosol, 1 Chromosol, and 1 Kandosol were collected from mainly pasture sites in New South Wales. The soils had different physico-chemical properties and there were some differences between the sites in climatic conditions. Soil microbial biomass carbon (MBC) was estimated by the chloroform-fumigation extraction method, and substrate utilisation patterns determined by the Biolog method were used to assess the amount, functional diversity, substrate richness and evenness, and community structure of the microorganisms in these soils. The amount of MBC (585 µg C/g) and the microbial diversity (H´ = 3.24) were high in soils that had high clay (33%), organic C (5.96%), total N (0.45%), free iron (7.06%), moisture content (50%), and cation exchange capacitiy (133.5 mmolc/kg). These soil properties, e.g. soil moisture (r2 = 0.72), organic C (r2 = 0.58), total N (r2 = 0.63), free iron (r2 = 0.44), and EC (r2 = 0.53), were positively correlated with MBC and microbial diversity index, whereas pH and sand and silt content showed negative correlations. The climatic factors (temperature and rainfall) had no significant influence on either MBC or diversity.
46
Samadi, Abbas, e R. J. Gilkes. "Forms of phosphorus in virgin and fertilised calcareous soils of Western Australia". Soil Research 36, n. 4 (1998): 585. http://dx.doi.org/10.1071/s97060.
Testo completoAbstract (sommario):
Total phosphorus (P), inorganic P (Pi), organic P, and several Pi fractions were determined for 8 fertilised calcareous soils under agriculture and their virgin analogues under natural bush to ascertain changes due to agricultural development. The relationships between soil properties and forms of P were also determined. In general, agricultural development of soils resulted in increases in total P (average 105% increase), Pi (154%), organic P (49%), Olsen P (200%), Colwell P (100%), and all Pi fractions compared with their virgin analogues. For the virgin soils, the abundance of the Pi fractions was in the order: Al-P>O-P (occluded P)>Fe-P>Ca10-P = Ca2-P>Ca8-P, which changed to Al-P>Ca8-P>Ca2-P>Ca10-P>Fe-P>O-P for fertilised soils. The average contribution of each fraction to the increase in total Pi was Al-P (29%), Ca8-P (26%), Ca2-P (18%), Fe-P (13%), Ca10-P (13%), and O-P (4%). The change in Ca8-P was closely correlated with the content of the active fraction of calcite in the soil (ACCE). The increase in Fe-P associated with agriculture was highly correlated with citrate-dithionite-bicarbonate (CDB) extractable Fe (Fed) and acid-ammonium oxalate extractable Fe (Feo). The increase in Al-P was correlated with the ratio of acid-ammonium oxalate extractable Al (Alo) to Feo. Both Olsen and Colwell NaHCO3-extractable P were highly correlated with Ca2-, Al-, Fe-, and Ca10-P, and total P values. Multiple regression analysis indicated that Ca2-P and Ca10-P were major contributors to available P as determined by the Olsen and Colwell soil tests.
47
Lewis, DC, AL Clarke e WB Hall. "Accumulation of plant nutrients and changes in soil properties of sandy soils under fertilized pasture in southeastern South-Australia .I. Phosphorus". Soil Research 25, n. 2 (1987): 193. http://dx.doi.org/10.1071/sr9870193.
Testo completoAbstract (sommario):
The accumulation of phosphorus applied as superphosphate over a 25-year period to pastures growing on sand over clay soils was measured in three areas of different rainfall in the south-east of South Australia. Total soil phosphorus levels increased in the 0-10 cm, 10-30 cm and 30 cm-clay layers for all areas, but no accumulation occurred in the clay layer. For every 100 kg ha-1 of single superphosphate (9.6% phosphorus) applied, 2.0, 3.2 and 3.5 kg ha-1 of phosphorus accumulated in the 0-10 cm layer for the Hundreds of Coles, Willalooka and Senior respectively. The recoveries of applied phosphorus in the sand layer for the three areas were 42, 57 and 75% for Coles, Willalooka and Senior respectively. The annual accumulation rates of organic phosphorus in the top 30 cm of soil ranged from 2.4 to 3.5 kg ha-1. By using a 'balance sheet' approach, the annual maintenance phosphate requirements for the three areas were calculated. These ranged from 60 to 165 kg ha-1 of superphosphate, and were associated with differences in leaching losses, stocking rates and organic phosphorus accumulation.
48
Moghtaderi, Tahereh, Ata Shakeri e Andrés Rodríguez-Seijo. "Potentially Toxic Element Content in Arid Agricultural Soils in South Iran". Agronomy 10, n. 4 (14 aprile 2020): 564. http://dx.doi.org/10.3390/agronomy10040564.
Testo completoAbstract (sommario):
Potentially toxic elements (PTE) are considered to be dangerous threats, both for human health and the environment. Here, the contamination level, sources, and ecological risks posed by PTE were investigated in 19 topsoils from agricultural lands in the Bandar Abbas County on the southern coast of Iran. The soil fraction <63 μm was used for the analysis of the pseudototal contents of PTE (arsenic, cadmium, cobalt, chromium, copper, lead, manganese, molybdenum, nickel, vanadium, and zinc). The results were analyzed using principal component analysis (PCA) and Pearson’s correlations, different pollution indices [enrichment factor (EF), contamination factor (Cf), and modified degree of contamination (mCd), and the potential ecological risk index (PERI). The results of the pollution indices showed that the contamination levels of the studied agricultural soils are low to moderate, while the average PERI values indicate that the ecological risks of PTE range from low to high in the soils of the studied area. Correlations and PCA analyses suggest that studied elements have three possible origins: geogenic (chromium, cobalt, copper, manganese, vanadium, and zinc), anthropogenic (cadmium, nickel, phosphorus and lead) and atmospheric (arsenic) sources. These findings are helpful for the long-term assessment of PTE in the Bandar Abbas County.
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Messiga, Aimé J., Camellia Lam e Yunkun Li. "Phosphorus saturation index and water-extractable phosphorus in high-legacy phosphorus soils in southern British Columbia, Canada". Canadian Journal of Soil Science 101, n. 3 (1 settembre 2021): 365–77. http://dx.doi.org/10.1139/cjss-2020-0129.
Testo completoAbstract (sommario):
Understanding of the risk of phosphorus (P) loss to the environment is crucial to monitor soil P and implement policies for P management. We assessed P sorption characteristics and adapted a P saturation index (PSI) for silage corn and blueberry fields in south coastal British Columbia (BC), Canada. We used 284 composite soil samples with contrasting P levels collected from eight silage corn and 23 blueberry fields across south coastal BC. The P sorption maximum (Smax) varied between 982 and 2532 mg P·kg−1 and was influenced by aluminum concentration and organic matter content. The degree of P saturation was related to water-extractable P (Pw) by a quadratic regression with R2 = 0.85. A critical Pw = 3.7 mg·kg−1 was established across the two cropping systems. The silage corn fields with pH > 5.5 had critical PSI value of 10.4%, and blueberry fields with pH < 4.7 had critical PSI value of 18.0%. These results showed that the risk of P loss from soil in the silage corn was high, but it was low for blueberry because the critical PSI for silage corn fields was lower than for blueberry fields, and therefore, saturation would be more easily reached, even though more P is applied to blueberry fields. The combination of a critical PSI and Pw as agri-environmental indicators will help farmers and professionals to identify fields with risk of P loss, to implement a nutrient management plan, and to monitor how this risk changes with time.
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Opeyemi, Akintola, Bodede Adewunmi e Abiola Oluwaseyi. "Physical and Chemical Properties of Soils in Gambari Forest Reserve Near Ibadan, South Western Nigeria." Journal of Bioresource Management 7, n. 2 (1 giugno 2020): 57–67. http://dx.doi.org/10.35691/jbm.0202.0132.
Testo completoAbstract (sommario):
The different features of soil greatly affect the flora and vegetative diversity of a forest. The physical and chemical characteristics of soils in Onigambari Forest Reserve were evaluated to assess the fertility and productivity status of the soils. Fifteen soil samples collected from different sample locations were analyzed for soil texture (sand, silt and clay), bulk density, porosity, pH, organic matter, total nitrogen, available phosphorus, exchangeable bases (Na, K, Ca and Mg) and available micronutrients (Zn, Cu, Fe and Mn). Texturally, the studied soils were loamy sand and sandy loam with percentage of sands (71.2-84.2 %), silts (7.4-10.4 %) and clay (6.4-19.4 %). The bulk density of the soils was 1.61-1.83 % while the porosity of the soils ranged from 35.2-44.1 %. The slightly acidic to neutral soil pH (5.90 - 6.60) and medium organic matter content (1.68 -2.60 %) suggest adequate level of soil nutrients. The soils had high total nitrogen (0.35 -0.65 %) and available phosphorus contents between 10.98 and 18.22mg/kg.