Articoli di riviste: "Crop rotation – Western Australia"

1

Turner, NC. "Crop production on duplex soils: an introduction". Australian Journal of Experimental Agriculture 32, n. 7 (1992): 797. http://dx.doi.org/10.1071/ea9920797.

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Abstract (sommario):

Duplex or texture-contrast soils occur over about 60% of the agricultural areas of south-west Western Australia. Annual crops of wheat, barley, oats, and lupins predominate on these soils, grown in rotation with annual pastures. The climate is characterised by cool, wet winters and hot, dry summers. Crop production is restricted to the winter and spring and is limited by waterlogging in the wet winter months and by water shortage during grain filling in spring. Research on crop production on duplex soils has been undertaken for the past 8 years by a collaborative team from the CSIRO Dryland Crops andyoils Program and the Western Australian Department of Agriculture. This research has been focussed on 3 sites at which processes limiting crop production on duplex soils have been highlighted. This special issue was initiated to summarise that research and to put it in its regional and national perspective. Additionally, opportunity was taken to compare and contrast experiences both within Western Australia and throughout Australia, and to draw out management options for crop production on duplex soils.

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2

Bhathal, J. S., e R. Loughman. "Ability of retained stubble to carry-over leaf diseases of wheat in rotation crops". Australian Journal of Experimental Agriculture 41, n. 5 (2001): 649. http://dx.doi.org/10.1071/ea00134.

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Increasingly, wheat rotations on sand-plain soils in Western Australia are being managed with stubble retention practices for reasons of moisture and soil conservation. A major concern in stubble retention practices is an associated increase in risk from septoria nodorum blotch (Phaeosphaeria nodorum) and yellow spot (Pyrenophora tritici-repentis). These pathogens frequently occur together in the region and survive in crop surface residues. The amount of disease carry-over on stubble is an important determinant of the severity of leaf diseases during the entire crop season. To provide a rationale for wheat leaf disease management in stubble retention rotation systems the extent to which retained wheat stubble induces disease in rotated crops was investigated. The frequency with which wheat stubble, which had been retained through a 1-year rotation, induced significant disease in seedling wheat was low (14%) over the 4-year period of study. While disease carry-over from wheat stubble retention in rotations is possible, it appears to be uncommon. The small proportion (1–8%) of retained wheat stubble that remained after germination of the return wheat crop in typical Western Australian farming systems further indicates that in general retained wheat stubble is not a significant source of disease carry-over in rotation wheat crops in this environment.

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3

Ewing, MA, AD Bathgate, RJ French e CK Revell. "The role of crop and pasture legumes in rotations on duplex soils". Australian Journal of Experimental Agriculture 32, n. 7 (1992): 971. http://dx.doi.org/10.1071/ea9920971.

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Duplex soils are prominent in southern Australia and are generally low in fertility. Their agricultural performance is, therefore, suboptimal in most circumstances without an exogenous source of nitrogen. This is often supplied by legumes which are grown in rotation with non-leguminous crops. Both crop and pasture legumes are now widely used in southern Australia and the contribution that they make to the non-legume phase of rotations is through nitrogen fixation and through other mechanisms such as cereal disease breaks. We use a mathematical programming model, MIDAS (Model of an Integrated Farming Dryland Agricultural System), to investigate the role of legumes in the low rainfall wheatbelt of Western Australia. The impact of legumes on farm profitability is assessed with a special focus on the contribution of legumes grown on a duplex soil. By using the model, the sensitivity of rotation choice on this duplex soil to changes in biological and economic parameters is explored. We conclude that crop legumes, in particular, have a firmly established role on sandy-surfaced duplex soils in low rainfall regions and that substantial increases in both the productivity and legume content of pasture would be required to outperform rotations which include crop legumes.

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4

Lawes, Roger, e Michael Renton. "The Land Use Sequence Optimiser (LUSO): A theoretical framework for analysing crop sequences in response to nitrogen, disease and weed populations". Crop and Pasture Science 61, n. 10 (2010): 835. http://dx.doi.org/10.1071/cp10026.

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The break crop effect, where a non-cereal crop provides relief from soil pathogens, may increase soil nitrogen reserves for a cereal and help minimise populations of herbicide resistant weeds. It is widely used in agriculture to maximise the economic return and yield of cereal crops. In Western Australia, cereal crops are being grown with increasing frequency, at the expense of less profitable break crops and we have developed a land use sequence optimiser (LUSO) to analyse strategic break crop decisions across a suite of price, yield, nitrogen fertiliser cost, soil borne disease load and weed load thresholds. The model is flexible and can easily be parameterised for a wide range of economic, edaphic and biotic parameters. We demonstrate its use in a strategic sense to determine economic and biotic thresholds that force a rotation change in a typical Western Australian cropping system.

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5

Kalkhoran, Sanaz Shoghi, David Pannell, Tas Thamo, Maksym Polyakov e Benedict White. "Optimal lime rates for soil acidity mitigation: impacts of crop choice and nitrogen fertiliser in Western Australia". Crop and Pasture Science 71, n. 1 (2020): 36. http://dx.doi.org/10.1071/cp19101.

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Abstract (sommario):

Many agricultural soils are naturally acidic, and agricultural production can acidify soil through processes such as nitrogen (N) fixation by legumes and application of N fertiliser. This means that decisions about mitigation of soil acidity (e.g. through application of lime), crop rotation and N fertiliser application are interdependent. This paper presents a dynamic model to determine jointly the optimal lime application strategies and N application rates in a rainfed cropping system in Western Australia. The model accounts for two crop rotations (with and without a legume break crop), for the acid tolerance of different crop types, and for differences in the acidifying effect of different N fertilisers. Results show that liming is a profitable strategy to treat acidic soils in the study region, but that there are interactions between N and acidity management. Choice of fertiliser affects optimal lime rates substantially, with the use of a more acidifying ammonium-based fertiliser leading to higher lime rates. The optimal liming strategy is also sensitive to inclusion of a legume crop in the rotation, because its fixed N can be less acidifying than fertiliser, and it allows a reduction in fertiliser rates. Higher rainfall zones have greater N leaching, which contributes to a higher optimal rate of lime. We find that injection of lime into the subsoil increases profit. Optimal lime rates in the absence of subsoil incorporation are higher than usual current practice, although the economic gains from increasing rates are small.

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6

Thomson, C. J., C. K. Revell, N. C. Turner, M. A. Ewing e I. F. Le Coultre. "Influence of rotation and time of germinating rains on the productivity and composition of annual pastures in Western Australia". Australian Journal of Agricultural Research 49, n. 2 (1998): 225. http://dx.doi.org/10.1071/a94082.

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A long-term rotation experiment located in south-western Australia was used to measure the effect of rotation and time of germinating rains on the productivity and botanical composition of grazed annual pastures in 2 contrasting seasons in an environment with an average annual rainfall of 325 mm. The density of self-regenerating seedlings of subterranean clover (Trifolium subterraneum), capeweed (Arctotheca calendula), and grasses (Lolium rigidum, Hordeum leporinum, Bromus diandrus) was greatly increased (approx. 3 times the density) when there was a second year of pasture after crop compared with the first year after crop. The lower plant density resulted in first-year pastures having only about 33% of the autumn biomass accumulation of second-year pastures. This difference in early pasture growth had no effect on total pasture production in 1992, but in 1993 total pasture production was 30% greater in second-year pastures compared with first-year pastures. Botanical composition varied between and within seasons with the percentage of subterranean clover increasing throughout the season and the percentage of capeweed decreasing throughout the season. Grasses comprised <20% of the biomass in all seasons and treatments. Production of subterranean clover seed in 1993 was higher in a 1 : 2 crop-pasture rotation than in a 1 : 1 crop-pasture rotation and direct drilling in the cropping phase increased seed set compared with conventional tillage in both 1 : 1 and 1 : 2 crop-pasture rotations. Capeweed seedlings emerged in large numbers after rainfall between February and May and subsequently showed a relative growth rate twice that of subterranean clover and the grasses, but exclusion of rainfall until June resulted in a significant reduction in the emergence of capeweed seedlings. Additionally, capeweed had a lower rate of seedling survival compared with other pasture species, and this is contrary to observations by other researchers that capeweed is highly resistant to moisture stress during early growth.

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7

Ward, P. R. "Predicting the impact of perennial phases on average leakage from farming systems in south-western Australia". Australian Journal of Agricultural Research 57, n. 3 (2006): 269. http://dx.doi.org/10.1071/ar04137.

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Rising watertables and dryland salinity in southern Australia are due to excess groundwater recharge after the replacement of native vegetation by annual crops and pastures. The inclusion of perennial plants into agricultural systems has been proposed as a possible method of recharge reduction, through the creation of a buffer (extra water storage capacity generated by the perennial in comparison with an annual crop or pasture). However, the role of perennial phases under conditions of highly episodic leakage is not well understood. In this paper, a simple Leakage/Buffer Model (LeBuM) was developed to determine the effect of perennial phases on long-term average annual leakage, incorporating episodic events. Mechanistic modelling studies on contrasting soil types were used to demonstrate that leakage for any given May–December period was directly related to soil water storage at 1 May. From this finding, it follows that leakage from a phase rotation can be calculated if the size of the buffer, and the leakage quantity in the absence of a buffer, are known for each stage of the rotation. LeBuM uses a long-term sequence of leakage values in the absence of a buffer as input, and the maximum buffer size, its rate of development, and the length of perennial and annual phases are specified as parameters. LeBuM was applied to leakage data modelled for 5 contrasting soil types over 100 years at 24 sites in the Western Australian wheatbelt. Phase rotations on duplex, waterlogging duplex, or loamy sand soils reduced leakage by >90% for regions with <380 mm annual rainfall, but were less effective in wetter regions and on deep sands or acid loamy sands. Nevertheless, phase rotations if adopted widely could delay the onset of salinity by as much as several decades.

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8

Osler, Graham H. R., Petra C. J. van Vliet, Craig S. Gauci e Lynette K. Abbott. "Changes in free living soil nematode and micro-arthropod communities under a canola - wheat - lupin rotation in Western Australia". Soil Research 38, n. 1 (2000): 47. http://dx.doi.org/10.1071/sr99050.

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Diversification of the crops used in wheat production systems provides alternative sources of income and can interrupt wheat pathogen lifecycles. Two important alternative crops in Western Australia are canola and lupins, which may both improve growth of following wheat. Improved growth of wheat following canola may be the consequence of biofumigation or increased root penetration by the wheat. Available nitrogen may be increased following lupins. We examined free-living soil fauna in a canola–wheat–lupin rotation near Moora, Western Australia, to determine the effects of these crops on the soil fauna. Each crop in the rotation was sampled in June, August, and October 1998. Nematodes were sorted into functional groups and arthropods were sorted to order level. Prostigmatid mites were the dominant arthropod group and they were sorted to morphospecies. An active and abundant faunal community was present under all crops, demonstrating that the canola variety in this study, Pinnacle TT, did not eliminate the free-living fauna. The structure of the mite communities changed throughout the year and the changes were different under the 3 crops. The soil arthropod communities were distinctly different under lupins compared with the other crops at the end of the growing season in 2 ways. First, 5 times more animals were present under the lupins than under wheat or canola, primarily due to an increase in the numbers of a tydeid and a tarsonemid mite species. Second, the tarsonemid species was always the second most abundant species under lupins but was infrequently the second ranked species under the other 2 crops. The soil arthropod communities were also different at the start of the growing season when the prostigmatid community under canola was dominated by a rhagidiid species, whilst under lupins and wheat a caligonellid and eupodid species dominated. The canola followed a lupin crop and therefore the difference in June may be attributed to the preceding lupins. Mite data from the lupin plots were consistent with a previously described succession from another environment. We hypothesise that if net nutrient mineralisation rates are greatest at the start of a succession then net mineralisation rates under lupins may be rapid at the end of the lupin crop and slow when the next crop is planted in the remaining lupin stubble. The difference between lupins and canola in their mite communities would then imply that net mineralisation rates are a factor creating differences between the effects of break crops on the following wheat crop.

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9

Humphries, A. W., X. G. Zhang, K. S. McDonald, R. A. Latta e G. C. Auricht. "Persistence of diverse lucerne (Medicago sativa sspp.) germplasm under farmer management across a range of soil types in southern Australia". Australian Journal of Agricultural Research 59, n. 2 (2008): 139. http://dx.doi.org/10.1071/ar07037.

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The persistence of a diverse group of lucerne (Medicago sativa sspp.) germplasm was evaluated under farmer management across a range of acidic and neutral-alkaline soils at 8 sites in South and Western Australia. Dryland field trials were sown in parallel with commercial lucerne paddocks being grown in rotation with cereal crops, remaining unfenced and under management by the farmer for the life of the stand. The combined differences in soil type, grazing management, and low rainfall contributed to large differences in average lucerne persistence between sites in South Australia and Western Australia. After 3 years, plant frequency (a measure of plant density used to monitor persistence) averaged 17% (at least 17 plants/m2) on the strongly acidic soils in Western Australia and 30% on the neutral-alkaline soils in South Australia (at least 30 plants/m2). Differences in persistence were attributed to the combined stresses of soil pH, drought conditions, and grazing management. Genetic correlation analyses between sites failed to show any clear patterns in the performance of entries at each site, except for a high correlation between 2 South Australian sites in close proximity. Highly winter-active germplasm was less persistent than other winter activity groups, but was higher yielding when assessed in an additional trial at Katanning, WA. Highly winter-active lucerne (class 9–10) should continue to be recommended for short (2–4 year) phases in rotation with cereals, and winter-active groups (6–8) should be recommend for longer (4–7 year) phases in rotations. The results of this evaluation are also being used to identify broadly adapted, elite genotypes in the breeding of new lucerne cultivars for the southern Australian cropping districts.

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10

Whish, J. P. M., P. Castor e P. S. Carberry. "Managing production constraints to the reliability of chickpea (Cicer arietinum L.) within marginal areas of the northern grains region of Australia". Australian Journal of Agricultural Research 58, n. 5 (2007): 396. http://dx.doi.org/10.1071/ar06179.

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The poor reliability of chickpea yield produced in the marginal (<600 mm rainfall) areas of the northern cropping zone is a constraint to the wide adoption of the crop. Chickpea is a valuable rotation crop and is currently the only viable winter grain legume suitable to this region. This paper uses results from in-crop monitoring and crop simulation, to identify practical management strategies to improve the reliability of chickpea crops in this region. APSIM-Chickpea successfully simulated the commercial yields of chickpea crops monitored during the study. Soil water at sowing and sowing date were identified as key determinants of yield. A ‘rule of thumb’ was derived, which showed that crops sown with a starting plant-available water of ~100 mm at sowing had an 80% probability of producing a better than break-even yield for the majority of the region and this was independent of the soil’s plant-available water capacity or crop sowing date. The probability of accumulating 100 mm of stored water in this western region is 90% following harvest of a May–sown wheat crop. Increased plant population improved crop yields in 60% of years, but this only translated to improved returns in ~50% of those years. The use of these simple management approaches will improve the reliability of chickpea production and ensure that these marginal areas have the option of a viable winter grain legume in their rotations.

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11

Moore, Andrew D. "Opportunities and trade-offs in dual-purpose cereals across the southern Australian mixed-farming zone: a modelling study". Animal Production Science 49, n. 10 (2009): 759. http://dx.doi.org/10.1071/an09006.

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Dual-purpose cereals are employed in the high-rainfall zone of southern Australia to provide additional winter forage. Recently there has been interest in applying this technology in the drier environments of South and Western Australia. It would therefore be useful to gain an understanding of the trade-offs and risks associated with grazing wheat crops in different locations. In this study the APSIM (Agricultural Production Systems Simulator) crop and soil simulation models were linked to the GRAZPLAN pasture and livestock models and used to examine the benefits and costs of grazing cereal crops at 21 locations spanning seven of the regions participating in the Grain & Graze research, development and extension program. A self-contained part of a mixed farm (an annual pasture–wheat rotation plus permanent pastures) supporting a breeding ewe enterprise was simulated. At each location the consequences were examined of: (i) replacing a spring wheat cultivar with a dual-purpose cultivar (cv. Wedgetail or Tennant) in 1 year of the rotation; and (ii) either grazing that crop in winter, or leaving it ungrazed. The frequency of early sowing opportunities enabling the use of a dual-purpose cultivar was high. When left ungrazed the dual-purpose cultivars yielded less grain on average (by 0.1–0.9 t/ha) than spring cultivars in Western Australia and the Eyre Peninsula but more (by 0.25–0.8 t/ha) in south-eastern Australia. Stocking rate and hence animal production per ha could be increased proportionately more when a dual-purpose cultivar was used for grazing; because of the adjustments to stocking rates, grazing of the wheat had little effect on lamb sale weights. Across locations, the relative reduction in wheat yield caused by grazing the wheats was proportional to the grazing pressure upon them. Any economic advantage of moving to a dual-purpose system is likely to arise mainly from the benefit to livestock production in Western Australia, but primarily from grain production in south-eastern Australia (including the Mallee region). Between years, the relationship between increased livestock production and decreased grain yield from grazing crops shifts widely; it may therefore be possible to identify flexible grazing rules that optimise this trade-off.

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12

Anderson, WK, e WR Smith. "Increasing wheat yields in a high rainfall area of Western Australia". Australian Journal of Experimental Agriculture 30, n. 5 (1990): 607. http://dx.doi.org/10.1071/ea9900607.

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Abstract (sommario):

Average commercial wheat yields in the southern, high rainfall area of Western Australia have seldom exceeded 1.5 t/ha and wheat is not widely grown. However, the average annual rainfall and length of growing season (>400 mm and >6 months) are conducive to much larger yields. Thirteen factorial experiments with mid and long season cultivars (Aroona and Osprey), 2 levels of applied nitrogen (N) (40 and 80 kg N/ha), 2 seed rates (50 and 100 kg/ha) and with or without fungicide were conducted at 8 sites over 2 seasons. The experiment was done to investigate combinations of cultivar and agronomic practices suitable for increased wheat production in long season environments in Western Australia. Largest grain yields (>4 t/ha) were obtained where wheat followed a grass-free break crop, and the mid season cultivar was used with 80 kg N/ha and 100 kg/ha of seed. Increases due to cultivar and seed rate were more consistent than those due to N, and increases from application of fungicide were less consistent. It is suggested that the optimal wheat production 'package' will include sowing in May in rotation with a grass-free break crop, seed rate of about 100 kg/ha and, when all other factors are optimal, N rates of over 40 kg/ha. The greatest yield increases were associated with the sites where wheat followed a grass-free crop. Increases due to other factors were relatively smaller. Hectolitre weight and percentage of small grain (<2 mm) often reached levels that would have entailed downgrading in commercial deliveries. However, in the most productive crops where root and leaf diseases were minimal, these quality parameters were seldom deficient and grain protein contents exceeded 10% at yields of up to 4 t/ha.

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13

Anderson, W. K., M. A. Hamza, D. L. Sharma, M. F. D'Antuono, F. C. Hoyle, N. Hill, B. J. Shackley, M. Amjad e C. Zaicou-Kunesch. "The role of management in yield improvement of the wheat crop—a review with special emphasis on Western Australia". Australian Journal of Agricultural Research 56, n. 11 (2005): 1137. http://dx.doi.org/10.1071/ar05077.

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Modern bread wheat (Triticum aestivum) has been well adapted for survival and production in water-limited environments since it was first domesticated in the Mediterranean basin at least 8000 years ago. Adaptation to various environments has been assisted through selection and cross-breeding for traits that contribute to high and stable yield since that time. Improvements in crop management aimed at improving yield and grain quality probably developed more slowly but the rate of change has accelerated in recent decades. Many studies have shown that the contribution to increased yield from improved management has been about double that from breeding. Both processes have proceeded in parallel, although possibly at different rates in some periods, and positive interactions between breeding and management have been responsible for greater improvements than by either process alone. In southern Australia, management of the wheat crop has focused on improvement of yield and grain quality over the last century. Adaptation has come to be equated with profitability and, recently, with long-term economic and biological viability of the production system. Early emphases on water conservation through the use of bare fallow, crop nutrition through the use of fertilisers, crop rotation with legumes, and mechanisation, have been replaced by, or supplemented with, extensive use of herbicides for weed management, reduced tillage, earlier sowing, retention of crop residues, and the use of ‘break’ crops, largely for management of root diseases. Yields from rainfed wheat crops in Western Australia have doubled since the late 1980s and water-use efficiency has also doubled. The percentage of the crop in Western Australia that qualifies for premium payments for quality has increased 3–4 fold since 1990. Both these trends have been underpinned by the gradual elimination or management of the factors that have been identified as limiting grain yield, grain quality, or long-term viability of the cropping system.

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14

Borger, C. P. D., G. P. Riethmuller e A. Hashem. "Emergence, survival and seed production of Enteropogon ramosus in a pasture - wheat rotation or continuous pasture rotation in the wheatbelt of Western Australia". Crop and Pasture Science 61, n. 8 (2010): 601. http://dx.doi.org/10.1071/cp10135.

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Enteropogon ramosus is a native, perennial, C4 grass species found within the wheatbelt of Western Australia. Emergence, survival, seed production and seed dormancy of E. ramosus was investigated in a continuous pasture rotation, a pasture–minimum tillage wheat rotation, and a pasture–minimum tillage wheat rotation where a cultivation event at the beginning of the pasture year was used to kill all E. ramosus plants. The results indicated that E. ramosus could germinate throughout the year, although plant density (ranging annually from 0 to 17 plants m−2) was lowest in conditions of low rainfall (summer–autumn drought). Seed production (estimated from seed head production, r = 91.7, P < 0.001) ranged from 0 to 2274 m–2 and was greatest in spring, in the continuous pasture rotation. Seed germinability reached 80–89%, following an initial 3 months of dormancy directly after seed production. Cultivation at the beginning of the pasture-crop rotation killed all plants, reduced emergence and prevented seed production for the 2-year period of the experiment. Soil disturbance from minimum tillage crop sowing reduced but did not eliminate E. ramosus plants. As a result, E. ramosus grew throughout the year in the minimum tillage cropping system. Further research is required to determine the competitive effect of E. ramosus on crop growth.

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15

Li, Guangdi D., Rajinder P. Singh, John P. Brennan e Keith R. Helyar. "A financial analysis of lime application in a long-term agronomic experiment on the south-western slopes of New South Wales". Crop and Pasture Science 61, n. 1 (2010): 12. http://dx.doi.org/10.1071/cp09103.

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Management of Acid Soils Through Efficient Rotations (MASTER) is a long-term agronomic experiment commenced in 1992. There were 3 fundamental treatment contrasts in this experiment: (a) annual systems v. perennial systems; (b) limed v. unlimed treatments; and (c) permanent pastures v. pasture–crop rotations. The soil was acidic to depth with pH (in CaCl2) below 4.5 and exchangeable Al above 40% at 0.10–0.20 m when the experiment started. Lime was applied every 6 years to maintain soil pHCa at 5.5 in the 0–0.10 m soil depth. A financial analysis was undertaken to estimate potential benefits and costs involved in liming acid soils on the south-western slopes of New South Wales, based on data from the MASTER experiment. The most important finding from the current study is that liming pastures on soils that have a subsurface acidity problem is profitable over the long-term for productive livestock enterprises. The pay-back period for liming pastures, grazed by Merino wethers, was 14 years for both annual and perennial pastures. More profitable livestock enterprises, such as prime lambs or growing-out steers, were estimated to reduce the pay-back period. This gives farmers confidence to invest in a long-term liming program to manage highly acid soils in the traditional permanent pasture region of the high-rainfall zone (550–800 mm) of south-eastern Australia. Results from the current study also confirmed that the total financial return from liming is greater if the land is suitable for operation of a pasture–crop rotation system. The positive cash flows generated from cropping in a relatively short time can significantly shorten the pay-back period for the investment in lime. But cropping without liming on soils with subsurface acidity was worse than grazing animals. Crop choice is crucial for the perennial pasture–crop rotation. Inclusion of high-value cash crops, such as canola or a wheat variety with high protein, would lead to a rise in the aggregate benefits over time as the soil fertility improved and soil acidity was gradually ameliorated.

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16

Monjardino, M., D. J. Pannell e S. B. Powles. "The economic value of pasture phases in the integrated management of annual ryegrass and wild radish in a Western Australian farming system". Australian Journal of Experimental Agriculture 44, n. 3 (2004): 265. http://dx.doi.org/10.1071/ea03050.

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Most cropping farms in Western Australia must deal with the management of herbicide-resistant populations of weeds such as annual ryegrass (Lolium rigidum Gaudin) and wild radish (Raphanus raphanistrum�L.). Farmers are approaching the problem of herbicide resistance by adopting integrated weed management systems, which allow weed control with a range of different techniques. One important question in the design of such systems is whether and when the benefits of including pasture in rotation with crops exceed the costs. In this paper, the multi-species resistance and integrated management model was used to investigate the value of including pasture phases in the crop rotation. The most promising of the systems examined appears to be so-called 'phase farming', involving occasional 3-year phases of pasture rather than shorter, more frequent and regular pasture phases. This approach was competitive with the best continuous cropping rotation in a number of scenarios, particularly where herbicide resistance was at high levels.

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17

Hamza, M. A., e W. K. Anderson. "Improving soil physical fertility and crop yield on a clay soil in Western Australia". Australian Journal of Agricultural Research 53, n. 5 (2002): 615. http://dx.doi.org/10.1071/ar01099.

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Abstract (sommario):

In the low rainfall area of Western Australia, clay soils with massive soil structure form a major part of the area sown to wheat. Yield increases on such soils have been poor in the last decade compared with those on other soil types. An experiment was conducted over 4 years (1997–2000) using a factorial combination of soil ripping to 0.4 m, application of commercial grade gypsum at 2.5 t/ha, and addition of complete nutrients based on soil test each year. All crop residues were retained after harvest and returned to the soil. The experiment was conducted in a wheat–field pea rotation at Merredin, WA. Soil water infiltration rate, soil strength, bulk density, water-stable aggregates, cation exchange capacity, and wheat yields were measured. Grain yields of wheat and field peas were increased by deep ripping, the addition of gypsum, or the addition of complete nutrients in some years. The main treatment effects on yield were additive, as significant interactions between the treatments on yield were seldom found. However, all the main treatments also significantly improved many of the soil physical properties related to crop growth. In 2000, 4 years after the treatments were applied, soil water infiltration rate was increased by more than 200%, strength of the topsoil decreased by around 1600 kPa, and soil bulk density decreased by 20%. Gypsum application increased water-stable aggregates, but soil mixing caused by deep ripping reduced them. The combination of soil ripping and gypsum application in the presence of complete nutrients and annual return of crop residues to the soil is suggested to improve crop grain yield and soil physical fertility on a range of Western Australian soils.

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18

Syme, H., T. L. Botwright Acuña, D. Abrecht e L. J. Wade. "Nitrogen contributions in a windmill grass (Chloris truncata) - wheat (Triticum aestivum L.) system in south-western Australia". Soil Research 45, n. 8 (2007): 635. http://dx.doi.org/10.1071/sr07159.

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Abstract (sommario):

Chloris truncata, a perennial grass that is native to Australia, has potential as a short-lived summer pasture in rotation with wheat and other winter crops in the low to medium rainfall zone of south-western Australia. In this paper we examine the nitrogen contributions from a C. truncata–wheat system, with the expectation that C. truncata may take up nitrate which would otherwise be lost to leaching, for later release to the following wheat crop. In glasshouse experiments, residual soil nitrate in bare soil was available for uptake and growth of wheat, with a greater response when N was applied. In contrast, wheat grown on C. truncata stubble was mostly reliant on recently mineralised nitrogen, as the previous rotation had depleted the soil of nitrate. Shoot stubble of C. truncata provided sufficient mineralised nitrogen such that the uptake of nitrogen and biomass of wheat equalled those from bare soil. Wheat grown on root stubble of C. truncata had half the biomass production of that grown on either bare soil or shoot stubble, with root + shoot stubble intermediate. In a field trial undertaken at Bruce Rock in Western Australia, nitrogen release from C. truncata stubble at low to intermediate stubble densities increased tiller production, nitrogen uptake, and growth of wheat, but not at the highest N rate in this season, which received below-average rainfall in July. These results provide initial evidence concerning how a C. truncata–wheat system could improve the N balance of the farming system, by potentially reducing the leaching loss of nitrate in autumn, and then releasing mineralised N from stubble when needed by a following wheat crop. While these results require further confirmation, especially in the field, they raise exciting prospects for an improved agronomic system, with potential benefits to N balance, carrying capacity, yield stability, and groundwater discharge. The system requires further study to quantify these processes, and explore their implications.

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19

Anderson, W. K., G. B. Crosbie e W. J. Lambe. "Production practices in Western Australia for wheats suitable for white, salted noodles". Australian Journal of Agricultural Research 48, n. 1 (1997): 49. http://dx.doi.org/10.1071/a95133.

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Abstract (sommario):

Wheat cultivars acceptable for the Noodle wheat segregation in Western Australia were compared with cultivars suitable for the Australian Standard White (ASW) grade over the period 1989–93. Yield and grain quality responses to sowing time, nitrogen fertiliser, soil type, and cropping history were examined to determine management practices most likely to result in wheat grain suitable for the production of white, salted noodles. Thirty experiments were conducted in the 300–450 mm average annual rainfall zone between Three Springs in the north (approx. 29° 30′S) and Newdegate in the south (approx. 33°10′S). The ASW cultivars, Spear, Kulin, and Reeves, outyielded the Noodle cultivars, Gamenya and Eradu, by 8–10% on average, but the yield difference was less at later sowings. The optimum sowing time was early May for most cultivars. The new cultivars, Cadoux (Noodle) and Tammin (potential Noodle, but classiffied General Purpose), tested in 1992 and 1993 in 12 experiments showed an optimum sowing time of late May, as did other midseason cultivars. Grain yields of May-sown crops were increased by 13 kg for every 1 kg of nitrogen applied, compared with 3 : 1 for June-sown crops. Previous legume history of the site and grass weed control in the crop also influenced the grain protein percentage. It was concluded that adoption of production guidelines that include sowing at, or near, the break of the season with about 40 kg/ha of nitrogen fertiliser, a rotation that includes 2-3 years of legume crop or pasture in the previous 5 years, and adequate grass weed control will result in an excellent chance (>80%) of producing grain proteins within the receival standards for the Noodle grade. Flour swelling volume (FSV), an indicator of noodle eating quality, was negatively correlated (not always significantly at P = 0·05) with grain protein percentage in 7 out of 8 experiments. FSV values were larger from sites located in the south of the study area and this appeared to be independent of protein and time-of-sowing effects. Small grain sievings (<2 mm) were increased by sowing after the end of May, especially in the longer season cultivars.

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20

Anderson, WK, GB Crosbie e K. Lemsom. "Production practices for high protein, hard wheat in Western Australia". Australian Journal of Experimental Agriculture 35, n. 5 (1995): 589. http://dx.doi.org/10.1071/ea9950589.

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Abstract (sommario):

Field experiments were conducted at 18 sites over 4 years in the eastern and north-eastern wheatbelt of Western Australia where average annual rainfall is <400mm, to investigate suitable techniques for the production of high protein (>13%) wheat in an area that traditionally produces grain of a much lower average protein percentage. Wilgoyne yielded as well as, or better than, any of the cultivars accepted into the Special Hard (SH) grade in Western Australia but 5-10% less than cultivars suitable for the Australian Standard White (ASW) grade. Differences between cultivars were greatest at the optimum sowing time in late May. Lower yields in early May were attributed to water stress during early growth or to frost damage during grain filling. The addition of nitrogen (N) fertiliser to crops sown after 1 June was less effective in increasing grain yield and grain protein than N added to earlier sowings. Most crops that produced >13% protein followed medic or field peas. The addition of N fertiliser was seldom required to produce this concentration of protein in crops that followed medic or peas. Crops following pasture with a low legume content or wheat had lower grain protein concentrations. Friable red-brown earth soils in a medic or pea rotation were able to achieve the required grain protein, but other combinations were not extensively tested. From these experiments, cultivars with inherently small grains due to their propensity to produce high levels of small grain screenings (whole grain through a 2-mm, slotted sieve) may be less able to increase yields economically by increasing kernel numbers per unit area under conditions in Western Australia.

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21

Monjardino, M., D. J. Pannell e S. B. Powles. "The economic value of haying and green manuring in the integrated management of annual ryegrass and wild radish in a Western Australian farming system". Australian Journal of Experimental Agriculture 44, n. 12 (2004): 1195. http://dx.doi.org/10.1071/ea03144.

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Abstract (sommario):

Most cropping farms in Western Australia must deal with the management of herbicide-resistant populations of weeds such as annual ryegrass (Lolium rigidum) and wild radish (Raphanus raphanistrum). Farmers are approaching the problem of herbicide resistance by adopting integrated weed management systems, which allow weed control with a range of different techniques. These systems include non-herbicide methods ranging from delayed seeding and high crop seeding rates to the use of non-cropping phases in the rotation. In this paper, the Multi-species RIM (resistance and integrated management) model was used to investigate the value of including non-cropping phases in the crop rotation. Non-crop options investigated here were haying and green manuring. Despite them providing excellent weed control, it was found that inclusion of these non-cropping phases did not increase returns, except in cases of extreme weed numbers and high levels of herbicide resistance.

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22

Hulugalle, N. R., P. C. Entwistle, F. Scott e J. Kahl. "Rotation crops for irrigated cotton in a medium-fine, self-mulching, grey Vertosol". Soil Research 39, n. 2 (2001): 317. http://dx.doi.org/10.1071/sr00035.

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Abstract (sommario):

Many cotton growers sow rotation crops after irrigated cotton (Gossypium hirsutum L.), assuming that they will improve soil quality and maintain profitability of cotton. Wheat (Triticum aestivum L.) is the most common rotation crop, although more recently, legumes such as faba bean (Vicia Faba L.) and chickpea (Cicer arietinum L.) have come into favour. This paper reports data on soil quality (organic C, nitrate-N, soil structure), yield (cotton lint and rotation crop grain yield, fibre quality), economic returns (gross margins/ha, gross margins/ML irrigation water), and management constraints from an experiment conducted from 1993 to 1998 near Wee Waa, north-western New South Wales, Australia. The soil is a medium-fine, self-mulching, grey Vertosol. The cropping sequences used were cotton followed by N-fertilised wheat (urea at 140 kg N/ha in 1993; 120 kg N/ha thereafter), unfertilised wheat, and unfertilised grain legumes (chickpea in 1993; faba bean thereafter), which were either harvested or the grain incorporated during land preparation. Soil organic C in the 0—0.6 m depth was not affected by the rotation crop, although variations occurred between times of sampling. Regression analysis indicated that there had been no net gain or loss of organic C between June 1993 and October 1998. Sowing leguminous rotation crops increased nitrate-N values. A net increase in root-zone nitrate-N reserves occurred with time (from June 1993 to October 1998) with all rotation crops. Soil compaction (measured as specific volume of oven-dried soil) was lower with wheat by October 1998. A net decrease in soil compaction occurred in the surface 0.15 m with all rotation crops between 1993 and 1998, whereas it increased in the 0.15–0.60 m depth. Cotton lint yield and quality, and gross margins/ha and gross margins/ML, were always higher where wheat was sown, with highest gross margins occurring when N fertiliser was applied. Applying N fertiliser to wheat did not significantly increase cotton lint yield and fibre quality, but increased gross margins of the cotton–wheat sequence due to higher wheat yield and protein percentage. Lint yield and fibre quality were decreased by sowing leguminous rotation crops. Management constraints such as lack of effective herbicides, insect damage, harvesting damage, and availability of suitable marketing options were greater with legumes than with wheat. Overall, wheat was a better rotation crop than grain legumes for irrigated cotton.

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23

Chapman, AL, e RJK Myers. "Nitrogen contributed by grain legumes to rice grown in rotation on the Cununurra soils of the Ord Irrigation Area, Western Australia". Australian Journal of Experimental Agriculture 27, n. 1 (1987): 155. http://dx.doi.org/10.1071/ea9870155.

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Abstract (sommario):

The uptake of nitrogen (N) by dry season rice following wet season crops of soybean (for grain or green manure), green gram, Sesbania cannabina (a native legume), a cereal (sorghum or dryland rice for grain), or bare fallow, was studied for 3 cropping cycles over 4 years. The work was done on Cununurra clay (0.04% N) at Kimberley Research Station near Kununurra, W.A., in the Ord Irrigation Area. Stubbles were returned to the soil except in the first cycle when (excluding the green manure treatment) all tops were removed from the plots at maturity. There was a 12-month bare fallow period between the first and second cycles. Dry season rice was drill-sown with or without 100 kg ha-1 of N applied as urea at permanent flooding. Soybean, green gram and Sesbania crops accumulated 290-360, 80-130 and 110-180 kg N ha-1, respectively, in the tops at maturity. An average of about 40 kg N ha-1 was present in the stem bases and roots (0-20 cm depth). Estimates of nitrogen fixation based on 15N dilution measurements ranged from 65-72% of total plant N when the legumes were grown after 12 months fallow, to 93-95% when they were grown immediately following dry season rice. Fertiliser N at 25 kg ha-1 applied presowing ('starter' N) had no significant effect on legume N yield at maturity. N returned in leaves, stems and hulls averaged 30, 50 and 80 kg N ha-1 for green gram, soybean and Sesbania, respectively. Rice grain yields and N uptake at maturity were generally highest after Sesbania and lowest after a wet season cereal crop. Differences among treatments were small and related to the quantity of N returned in residues. On average, 11% of the N in the residues was recovered in the tops of the following rice crop. Rice yields increased over the 4-year period, but mean increases were similar for legume and non-legume treatments. The average apparent recovery of N applied as urea to dry season rice at permanent flooding was 76%. The inclusion of a soybean cash crop in the rotation offers the possibility of a marginal reduction in the need for N fertiliser.

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24

Dolling, P. J. "Water use and drainage under phalaris, annual pasture, and crops on a duplex soil in Western Australia". Australian Journal of Agricultural Research 52, n. 2 (2001): 305. http://dx.doi.org/10.1071/ar99167.

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Abstract (sommario):

Rising water tables in southern Western Australia are causing waterlogging and salinity problems. These issues are related to a lower level of water use by annual plants than by the native vegetation. Phalaris can use more water than annual pastures and crops because of deeper rooting characteristics and longer growing season. However, there is limited information on the water use of phalaris in the Western Australian environment. There is also very little information on water balances under annual crops and pastures outside the growing season. A field experiment was carried out on a duplex soil between March 1994 and March 1999. Annual rainfall varied between 321 and 572 mm. The study examined soil water content, deep drainage, and productivity of phalaris-based pasture, continuous annual pasture, annual pasture–wheat rotation, and a wheat–lupin rotation. The results showed that the phalaris-based pasture after the establishment year was 25% (1.9 t dry matter/ha) more productive than continuous annual pasture, with the main difference occurring in late spring–early summer. The phalaris-based pasture used, on average, 45 mm/year more water and reduced drainage below 1 m by 44 mm/year compared with the annual pastures and crops. Total drainage below 1 m was 30 mm under the phalaris-based pasture and 74 mm under annual pasture. The greater water use in the phalaris-based pasture occurred in late spring and early summer. Although differences in total biomass per year occurred between wheat in different rotations there was no difference in the soil water storage prior to the break of the season. There was also no difference in the soil water balance between any of the annual crops and pastures. Differences in soil water storage did occur in some years in October but disappeared by May the following year.

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25

Ward, P. R., D. J. M. Hall, S. F. Micin, K. Whisson, T. M. Willis, K. Treble e D. Tennant. "Water use by annual crops. 1. Role of dry matter production". Australian Journal of Agricultural Research 58, n. 12 (2007): 1159. http://dx.doi.org/10.1071/ar07076.

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Abstract (sommario):

In southern Australia, expanding dryland salinity is the result of increased deep drainage associated with widespread replacement of native perennial vegetation by annual agricultural crops and pastures. Although perennial pastures have been shown to assist in slowing salinisation, their adoption has been slow, and annual crops and pastures are likely to remain as the dominant land use for the foreseeable future. Therefore, understanding the water balance of annual crops and pastures, and how it can be manipulated, is important in trying to manage salinity. In this research we investigate the effect of varying levels of dry matter production on components of the water balance (soil evaporation, transpiration, soil water storage, and drainage) for annual crops at contrasting sites and soil types in south-western Australia. Dry matter production was controlled by fertiliser addition and crop rotation, and varied by a factor of up to 2, depending on seasonal conditions. Deep drainage was zero for most sites and years, but where it was greater than zero, there was no discernible effect due to production level. Out of a total of 14 site/year comparisons, the difference in soil water extraction associated with greater dry matter production averaged 5 mm, and was greater than 20 mm on only 1 occasion. However, high dry matter production was associated with greater transpiration, at the expense of soil evaporation. Manipulating dry matter production is unlikely to have a substantial effect on deep drainage and the expansion of dryland salinity in south-western Australia.

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26

Thomas, G. J., W. J. MacLeod e M. W. Sweetingham. "Incidence of root and hypocotyl diseases in lupin crops in Western Australia between 1986 and 2005". Crop and Pasture Science 61, n. 3 (2010): 241. http://dx.doi.org/10.1071/cp09208.

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Abstract (sommario):

Three separate surveys were carried out in commercial lupin crops in the major lupin growing region of Western Australia in 1986, 1990, and 2004–05. In total, 333 sites were sampled and plants assessed for the incidence and cause of root and hypocotyl rots. Measurements were made of plant density and sowing depth at all sites. In all surveys, root rot was more common than hypocotyl rot. Root rot occurred in more than 95% of sites in each survey; however, a greater proportion of sites had high levels of root rot in early surveys. The incidence of root rot within sites decreased from an average of 34.9% in 1986 to 10.2% in 2004–05. Hypocotyl rot incidence varied among surveys, incidence of infected paddocks, and within-paddock incidence was greatest in the 1990 survey. Hypocotyl rot incidence was lowest in the 2004–05 survey. Rhizoctonia solani and Pleiochaeta setosa were commonly isolated from root lesions and R. solani was the predominant pathogen isolated from hypocotyl lesions. Analysis of the R. solani isolates by pectic zymogram showed that the ZG3 strain was most regularly isolated from roots and hypocotyls. This series of surveys indicates that the incidence of root rots in commercial lupin paddocks in Western Australia has decreased dramatically over the past 20 years; however, root rot still occurs in most paddocks regardless of soil type, location, crop rotation, and management systems.

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27

Richards, Mark F., Aaron L. Preston, Tony Napier, Leigh Jenkins e Lancelot Maphosa. "Sowing Date Affects the Timing and Duration of Key Chickpea (Cicer arietinum L.) Growth Phases". Plants 9, n. 10 (24 settembre 2020): 1257. http://dx.doi.org/10.3390/plants9101257.

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Abstract (sommario):

Chickpea is the main legume rotation crop within farming systems in northern New South Wales (NSW), Australia, and is grown mainly under rainfed conditions. Recent expansion of chickpea growing areas in southern and central western NSW expose them to abiotic stresses; however, knowledge about how these stresses affect overall crop development is limited. This study aimed to examine the influence of sowing time on the timing and duration of key chickpea phenological growth phases in southern and central western environments of NSW. Experiments were conducted over two years in southern NSW (Leeton, Wagga Wagga and Yanco (one year)) and central western NSW (Trangie) to identify phenology responses. Climatic, phenology and experimental site data was recorded, and the duration of growth phases and growing degree days calculated. Early sowing (mid-April) generally delayed flowering, extending the crop’s vegetative period, and the progressive delay in sowing resulted in shorter vegetative and podding growth phases. All genotypes showed photoperiod sensitivity, and the mean daily temperature at sowing influenced time to emergence and to some extent crop establishment. This study concludes that environmental factors such as temperature, moisture availability and day length are the main drivers of phenological development in chickpea.

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28

Kelly, Sean, e Ian Riley. "Radopholus nativus (Nematoda: Pratylenchidae), a potential economic pest of wheat in Western Australia". Nematology 3, n. 1 (2001): 25–30. http://dx.doi.org/10.1163/156854101300106856.

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Abstract (sommario):

AbstractLarge population densities (more than 100 000 per g dry weight of roots) of Radopholus nativus apparently caused economic damage to wheat near Wyalkatchem, Western Australia. Plants in large areas of poor growth were colonised by R. nativus, whereas in areas of better growth Pratylenchus neglectus occurred at lower population densities. The boundary between the areas was distinct. In the same year (1998), a further nine wheat samples were found to be infested with R. nativus through examination of 300 diagnostic samples submitted by Western Australian growers. Mixed Radopholus/Pratylenchus populations occurred in six of those samples. Populations of R. nativus were widely dispersed throughout the cropping areas of the State. It is concluded that R. nativus has the potential under certain conditions and/or crop rotations to reach high population density and cause economic loss.

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29

Loss, SP, GSP Ritchie e AD Robson. "Effect of lupins and pasture on soil acidification and fertility in Western Australia". Australian Journal of Experimental Agriculture 33, n. 4 (1993): 457. http://dx.doi.org/10.1071/ea9930457.

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Abstract (sommario):

An 'across the fence' comparison of farmer paddocks with nearby virgin bush sites was made at 3 locations, to measure the effects of lupins and subterranean clover based pastures on the chemical properties of the soil. Estimated rates of acidification in the 0-60 cm depth were 0.29-0.55 kmol H+/ha.year for wheat-lupin paddocks and 0.16-0.2 1 kmol H+/ha .year for pasture paddocks. A significant proportion of this acidification occurred below 20 cm, particularly in the lupin paddocks (up to 70% of the total). Severe water repellency had developed at 1 location that had produced 30 lupin crops with the occasional wheat crop. Despite these detrimental effects, lupins maintained soil mineral nitrogen and organic matter contents and electrical conductivities similar to those in pasture paddocks, even though the soils in the lupin rotations had been sown to wheat more frequently.

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30

Spencer, Beren, Amir Abadi, John Bartle, Robert Sudmeyer, Sarah Van Gent, Mark Gibberd e Ayalsew Zerihun. "Determinants of the economic viability of mallee eucalypts as a short rotation coppice crop integrated into farming systems of Western Australia". GCB Bioenergy 13, n. 1 (15 novembre 2020): 242–56. http://dx.doi.org/10.1111/gcbb.12775.

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31

Hulugalle, N. R., T. B. Weaver, L. A. Finlay e P. Lonergan. "Soil properties, black root-rot incidence, yield, and greenhouse gas emissions in irrigated cotton cropping systems sown in a Vertosol with subsoil sodicity". Soil Research 50, n. 4 (2012): 278. http://dx.doi.org/10.1071/sr12088.

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Abstract (sommario):

Comparative studies of soil quality and energy use in two- and three-crop rotations in irrigated cotton (Gossypium hirsutum L.) based cropping systems under varying stubble management practices in Australian Vertosols are sparse. Our primary objective was to quantify selected soil quality indices (salinity, sodicity, exchangeable cations, nitrate-N, pH), crop yields, and greenhouse gas emissions in four irrigated cotton-based cropping systems sown on permanent beds in a Vertosol with subsoil sodicity near Narrabri in north-western New South Wales. A secondary objective was to evaluate the efficacy of sowing vetch in rotation with cotton over a long period on the incidence of black root-rot in cotton seedlings. Results presented in this report pertain to the period June 2005–May 2011. The experimental treatments were: cotton–cotton; cotton–vetch (Vicia benghalensis L.); cotton–wheat (Triticum aestivum L.), where wheat stubble was incorporated; and cotton–wheat–vetch, where wheat stubble was retained as in-situ mulch. Vetch was terminated during or just before flowering by a combination of mowing and contact herbicides, and the residues were retained as in-situ mulch. Soil pH, electrical conductivity (EC1 : 5), Cl–, NO3–-N, exchangeable cations, exchangeable sodium percentage (ESP), electrochemical stability index (= EC1 : 5/ESP), and EC1 : 5/ESC (exchangeable sodium concentration) were evaluated in samples taken from the 0–1.2 m depth before sowing cotton during late September or early October of each year. Incidence of black root-rot was assessed 6 weeks after sowing cotton. Compared with sowing cotton every year, including wheat in cotton-based cropping systems improved cotton yield and reduced soil quality decline, emissions of carbon dioxide equivalents (CO2-e) per unit area, and CO2-e emissions per unit of cotton yield. Including vetch in the rotation was of negligible benefit in terms of yield and CO2-e emissions per unit of yield. The rate of soil quality decline was unaffected by including vetch in a cotton–wheat rotation but was accelerated when included in a cotton–cotton sequence. Among all cropping systems, soil quality was best with cotton–wheat and cotton–wheat–vetch but poorest with cotton–vetch. Although CO2-e emissions associated with growing 1 ha of cotton could be reduced by 9% by growing vetch because of substituting fixed atmospheric N for N fertiliser derived from fossil fuels, this advantage was partly negated by the emissions from farming operations associated with growing a vetch crop. Relative to a two-crop rotation (one cotton–one rotation crop), negligible benefits in terms of yield, soil quality, greenhouse gas emissions, and black root-rot control accrued from a three-crop rotation (one cotton–two rotation crops). Incidence of black root-rot increased as the number of cotton crops sown increased. In addition to the cropping systems, soil quality indices and yield were significantly influenced by irrigation water quality and climate.

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Damon, P., S. J. Rance, K. Shammas, A. M. O'Connell, T. S. Grove e R. McMurtrie. "Contribution of decomposing harvest residues to nutrient cycling in a second rotation Eucalyptus globulus plantation in south-western Australia". Biology and Fertility of Soils 38, n. 4 (1 agosto 2003): 228–35. http://dx.doi.org/10.1007/s00374-003-0654-x.

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33

Bell, Michael J., Wayne Strong, Denis Elliott e Charlie Walker. "Soil nitrogen—crop response calibration relationships and criteria for winter cereal crops grown in Australia". Crop and Pasture Science 64, n. 5 (2013): 442. http://dx.doi.org/10.1071/cp12431.

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Abstract (sommario):

More than 1200 wheat and 120 barley experiments conducted in Australia to examine yield responses to applied nitrogen (N) fertiliser are contained in a national database of field crops nutrient research (BFDC National Database). The yield responses are accompanied by various pre-plant soil test data to quantify plant-available N and other indicators of soil fertility status or mineralisable N. A web application (BFDC Interrogator), developed to access the database, enables construction of calibrations between relative crop yield ((Y0/Ymax) × 100) and N soil test value. In this paper we report the critical soil test values for 90% RY (CV90) and the associated critical ranges (CR90, defined as the 70% confidence interval around that CV90) derived from analysis of various subsets of these winter cereal experiments. Experimental programs were conducted throughout Australia’s main grain-production regions in different eras, starting from the 1960s in Queensland through to Victoria during 2000s. Improved management practices adopted during the period were reflected in increasing potential yields with research era, increasing from an average Ymax of 2.2 t/ha in Queensland in the 1960s and 1970s, to 3.4 t/ha in South Australia (SA) in the 1980s, to 4.3 t/ha in New South Wales (NSW) in the 1990s, and 4.2 t/ha in Victoria in the 2000s. Various sampling depths (0.1–1.2 m) and methods of quantifying available N (nitrate-N or mineral-N) from pre-planting soil samples were used and provided useful guides to the need for supplementary N. The most regionally consistent relationships were established using nitrate-N (kg/ha) in the top 0.6 m of the soil profile, with regional and seasonal variation in CV90 largely accounted for through impacts on experimental Ymax. The CV90 for nitrate-N within the top 0.6 m of the soil profile for wheat crops increased from 36 to 110 kg nitrate-N/ha as Ymax increased over the range 1 to >5 t/ha. Apparent variation in CV90 with seasonal moisture availability was entirely consistent with impacts on experimental Ymax. Further analyses of wheat trials with available grain protein (~45% of all experiments) established that grain yield and not grain N content was the major driver of crop N demand and CV90. Subsets of data explored the impact of crop management practices such as crop rotation or fallow length on both pre-planting profile mineral-N and CV90. Analyses showed that while management practices influenced profile mineral-N at planting and the likelihood and size of yield response to applied N fertiliser, they had no significant impact on CV90. A level of risk is involved with the use of pre-plant testing to determine the need for supplementary N application in all Australian dryland systems. In southern and western regions, where crop performance is based almost entirely on in-crop rainfall, this risk is offset by the management opportunity to split N applications during crop growth in response to changing crop yield potential. In northern cropping systems, where stored soil moisture at sowing is indicative of minimum yield potential, erratic winter rainfall increases uncertainty about actual yield potential as well as reducing the opportunity for effective in-season applications.

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Lefroy, E. C., R. J. Stirzaker e J. S. Pate. "The influence of tagasaste (Chamaecytisus proliferus Link.) trees on the water balance of an alley cropping system on deep sand in south-western Australia". Australian Journal of Agricultural Research 52, n. 2 (2001): 235. http://dx.doi.org/10.1071/ar00035.

Testo completo

Abstract (sommario):

Components of the water balance of an alley cropping system were measured to assess the extent to which tree rows 30 m apart with access to a fresh, perched watertable at 5 m depth were able to capture deep drainage from an inter-cropped cereal–legume rotation. Neutron probe data showed that the 4-year-old trees, cut back to 0.6-m high at the beginning of the experiment, depleted soil water to 2, 4, and 8 m laterally from the tree rows in their first, second, and third years of coppice regrowth, respectively. Combining data from soil water depletion in summer and comparisons of deuterium: hydrogen ratios of groundwater, xylem sap of trees, and herbaceous plants, it was shown that tagasaste trees drew on soil water for 80% of their transpiration in the first winter and 40% in the second, while switching to near total dependence on groundwater each summer and early autumn. Tree water use on a whole plot basis was 170 mm in 1997 (68% from groundwater) v. 167 mm in 1998 (73% from groundwater). Recharge to the perched watertable was estimated to be 193 mm under sole crop in 1998 (52% of rainfall), reducing to 32 mm when uptake of groundwater by trees was included. The degree of complementarity between tagasaste trees and crops in alley cropping used for water management is quantified for 1998 by calculating the ratio of the distance over which trees reduced drainage to zero to the distance over which they reduced crop yield to zero. It is concluded that segregated monocultures of trees and crops would be a more appropriate strategy than a closely integrated system such as alley cropping in this case.

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35

Evans, J., A. M. McNeill, M. J. Unkovich, N. A. Fettell e D. P. Heenan. "Net nitrogen balances for cool-season grain legume crops and contributions to wheat nitrogen uptake: a review". Australian Journal of Experimental Agriculture 41, n. 3 (2001): 347. http://dx.doi.org/10.1071/ea00036.

Testo completo

Abstract (sommario):

The removal of nitrogen (N) in grain cereal and canola crops in Australia exceeds 0.3 million t N/year and is increasing with improvements in average crop yields. Although N fertiliser applications to cereals are also rising, N2-fixing legumes still play a pivotal role through inputs of biologically fixed N in crop and pasture systems. This review collates Australian data on the effects of grain legume N2 fixation, the net N balance of legume cropping, summarises trends in the soil N balance in grain legume–cereal rotations, and evaluates the direct contribution of grain legume stubble and root N to wheat production in southern Australia. The net effect of grain legume N2 fixation on the soil N balance, i.e. the difference between fixed N and N harvested in legume grain (Nadd) ranges widely, viz. lupin –29–247 kg N/ha (mean 80), pea –46–181 kg N/ha (mean 40), chickpea –67–102 kg N/ha (mean 6), and faba bean 8–271 kg N/ha (mean 113). Nadd is found to be related to the amount (Nfix) and proportion (Pfix) of crop N derived from N2 fixation, but not to legume grain yield (GY). When Nfix exceeded 30 (lupin), 39 (pea) and 49 (chickpea) kg N/ha the N balance was frequently positive, averaging 0.60 kg N/kg of N fixed. Since Nfix increased with shoot dry matter (SDM) (21 kg N fixed/t SDM; pea and lupin) and Pfix (pea, lupin and chickpea), increases in SDM and Pfix usually increased the legume’s effect on soil N balance. Additive effects of SDM, Pfix and GY explained most (R2 = 0.87) of the variation in Nadd. Using crop-specific models based on these parameters the average effects of grain legumes on soil N balance across Australia were estimated to be 88 (lupin), 44 (pea) and 18 (chickpea) kg N/ha. Values of Nadd for the combined legumes were 47 kg N/ha in south-eastern Australia and 90 kg N/ha in south-western Australia. The average net N input from lupin crops was estimated to increase from 61 to 79 kg N/ha as annual rainfall rose from 445 to 627 mm across 3 shires in the south-east. The comparative average input from pea was 37 to 47 kg N/ha with least input in the higher rainfall shires. When the effects of legumes on soil N balance in south-eastern Australia were compared with average amounts of N removed in wheat grain, pea–wheat (1:1) sequences were considered less sustainable for N than lupin–wheat (1:1) sequences, while in south-western Australia the latter were considered sustainable. Nitrogen mineralised from lupin residues was estimated to contribute 40% of the N in the average grain yield of a following wheat crop, and that from pea residues, 15–30%; respectively, about 25 and 15 kg N/ha. Therefore, it was concluded that the majority of wheat N must be obtained from pre-existing soil sources. As the amounts above represented only 25–35% of the total N added to soil by grain legumes, the residual amount of N in legume residues is likely to be important in sustaining those pre-existing soil sources of N.

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36

MacNish, GC, e DA Nicholas. "Some effects of field history on the relationship between grass production in subterranean clover pasture, grain yield and take-all (Gaeumannomyces graminis var. tritici) in a subsequent crop of wheat at Bannister, Western Australia". Australian Journal of Agricultural Research 38, n. 6 (1987): 1011. http://dx.doi.org/10.1071/ar9871011.

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Abstract (sommario):

The relationship between grass production in subterranean clover pastures with two different rotation histories and take-all in a subsequent wheat crop following barley was studied. Grass production in the pastures ranged from 0 to 1700 kg ha-1. The incidence of take-all in the wheat crop ranged from 10 to l00%, while the take-all severity percentage ranged from 4 to 99.In one rotation series (pasture 9 years; barley, barley, pasture, wheat), each kilogram increase in grass production in the last pasture year caused a 0.087% increase in the take-all severity rating. In the second series (pasture 7 years; oats, pasture 3 years; barley, wheat), each kilogram increase in grass production caused a 0.040% increase in severity. These figures are significantly different (P < 0.05). Thus the field history ranging back at least four seasons influenced the effects that grass level in the last pasture year had on take-all severity. Reductions in wheat yields ranged from 8.6 to 10.5 kg ha-1 for each 1% increase in take-all severity rating.

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37

Hulugalle, N. R., G. Nachimuthu, K. Kirkby, P. Lonergan, V. Heimoana, M. D. Watkins e L. A. Finlay. "Sowing maize as a rotation crop in irrigated cotton cropping systems in a Vertosol: effects on soil properties, greenhouse gas emissions, black root rot incidence, cotton lint yield and fibre quality". Soil Research 58, n. 2 (2020): 137. http://dx.doi.org/10.1071/sr19242.

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Although sowing winter cereal crops in rotation with irrigated cotton (Gossypium hirsutum L.) is practised by many Australian cotton growers, summer cereals such as maize (Zea mays L.) are sown more frequently than previously. Our objective was to quantify the impact of sowing maize rotation crops on soil properties, greenhouse gas emissions, incidence of black root rot (BRR) disease and crop yields in an ongoing long-term experiment located in a Vertosol in north-western New South Wales. The historical treatments were cotton monoculture (sown after either conventional or minimum tillage) and a minimum-tilled cotton–wheat (Triticum aestivum L.) rotation. The experiment was redesigned in 2011 by splitting all plots and sowing either maize during summer following the previous year’s cotton or retaining the historical cropping system as a control. pH and exchangeable cation concentrations were highest, and electrical conductivity (EC1:5) lowest during 2012, the season following a flood event, but were unaffected by sowing maize. In subsequent seasons, with the onset of dry conditions, pH and cation concentrations decreased, and EC1:5 increased. The upper horizons (0–0.3 m) of plots where maize was sown had higher concentrations of exchangeable Ca and Mg during 2012, and 0.45–1.20 m had higher concentrations of exchangeable Na and exchangeable sodium percentage, but these differences disappeared in subsequent years. Soil organic carbon (SOC) in the surface 0.15 m was higher with maize, with differences becoming evident three years after maize was first sown but without any increases in SOC storage. Soil under maize was less resilient to structural degradation. BRR incidence was lower in maize-sown plots only during 2012. Stepwise linear regression suggested that high concentrations of exchangeable Ca and Mg in the surface 0.15 m played a role in reducing BRR incidence during 2012. Maize rotation introduced into cotton monocultures improved lint yields and reduced greenhouse gas emissions but had little impact in a minimum-tilled cotton–wheat rotation. Maize is a suitable rotation crop for irrigated cotton in a two-crop sequence but is of little advantage in a cotton–wheat–maize sequence.

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38

Anderson, G. C., I. R. P. Fillery, F. X. Dunin, P. J. Dolling e S. Asseng. "Nitrogen and water flows under pasture - wheat and lupin - wheat rotations in deep sands in Western Australia. 2. Drainage and nitrate leaching". Australian Journal of Agricultural Research 49, n. 3 (1998): 345. http://dx.doi.org/10.1071/a97142.

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Abstract (sommario):

Quantification of nitrate (NO-3) leaching is fundamental to understanding the efficiency with which plants use soil-derived nitrogen (N). A deep sand located in the northern wheatbelt of Western Australia was maintained under a lupin (Lupinus angustifolius)-wheat (Triticum aestivum) and a subterranean clover (Trifolium subterraneum) based annual pasture-wheat rotation from 1994to 1996. Fluxes of water and NO-3 through, and beyond, the root-zone were examined. Drainage was calculated on a daily basis from measurements of rainfall, evapotranspiration, and the change in soil water content to a depth of 1·5 m. Evapotranspiration was estimated from Bowen ratio measurements,and soil water content was determined by time domain reflectrometry. Soil was sampled in layers to1·5 m at the onset of winter rains and analysed for NO-3 . Ceramic suction cups were installed at 0·25, 0·4, 0·6, 0·8, 1·0, 1·2, and 1·4 m to sample soil solution from June to mid August. The NO-3 leached from each layer was computed by multiplying the daily drainage through each layer by the estimated concentration of NO-3 within the layer. The estimated concentration of NO-3 in a layer was calculated by taking into account NO-3 either entering that layer through mineralisation and leachingor leaving the layer through plant uptake. Mineral N was added to the surface 0·2 m in accordance with measured rates of net N mineralisation, and daily N uptake was calculated from the measured above-ground plant N derived from soil N. Root sampling was undertaken to determine root lengthdensity under pastures, lupin, and wheat. Cumulative drainage below 1·5 m was similar under wheat and lupin, and accounted for 214 mmfrom 11 May to 15 August 1995 and 114 mm from 2 July to 15 September 1996. The cumulative evapotranspiration (Ea) over these periods was 169 mm from a wheat crop in 1995, and 178 mm from a lupin crop in 1996. The amount of NO-3 in soil at the start of the growing season was afiected by previous crop, with a lower range following wheat (31-68 kg N/ha) than following legumes (40-106 kgN/ha). These large quantities of NO-3 in the soil at the break of the season contributed substantially to NO-3 leaching. Leaching of NO-3 below 1·5 m in wheat crops accounted for 40-59 kg N/ha where these followed either lupin or pasture. In contrast, less NO-3 was found to leach below 1·5 m in pastures (17-28 kg N/ha). Greater N uptake by capeweed (Arctotheca calendula L.) than by either wheat or lupin was the main reason for the lower amount of NO-3 leached in pastures.

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39

Nichols, P. G. H., M. J. Barbetti, G. A. Sandral, B. S. Dear, C. T. de Koning, D. L. Lloyd, P. M. Evans, A. D. Craig, P. Si e M. P. You. "Urana subterranean clover (Trifolium subterraneum L. var. subterraneum)". Australian Journal of Experimental Agriculture 46, n. 8 (2006): 1105. http://dx.doi.org/10.1071/ea05083.

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Abstract (sommario):

Urana is a hardseeded, moderately early flowering F5-derived crossbred subterranean clover of var. subterraneum [(Katz. et Morley) Zohary and Heller] developed by the collaborating organisations of the National Annual Pasture Legume Improvement Program. It has been selected for release as a new cultivar on the basis of its high winter and spring herbage production and overall field performance relative to other subterranean clovers of similar maturity. Urana is recommended for sowing in Western Australia, New South Wales, Victoria, South Australia and Queensland. It is best suited to well-drained, moderately acidic soils in areas with a growing season of 5–7 months, which extends into mid-October. Urana is suited to phase farming and crop rotations. It has been granted Plant Breeders Rights in Australia.

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40

Sudmeyer, R. A., T. Daniels, H. Jones e D. Huxtable. "The extent and cost of mallee - crop competition in unharvested carbon sequestration and harvested mallee biomass agroforestry systems". Crop and Pasture Science 63, n. 6 (2012): 555. http://dx.doi.org/10.1071/cp12129.

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Mallee-based agroforestry has potential to provide farmers with new income sources derived from biofuels, biofeedstocks, and carbon sequestration. Although mallees are planted on >12 700 ha across the south-west of Western Australia, very little commercial harvesting of mallee has occurred to date. The development of biomass processing industries is constrained by lack of robust information regarding the productivity of integrated mallee and agricultural systems. This study addresses this constraint by quantifying the productivity and economics of agricultural crops and pastures growing in the competition zone adjacent to mallee belts at 15 sites across the Western Australian wheatbelt. The sites covered a range of climate and edaphic conditions, three mallee species (Eucalyptus polybractea R Baker, E. loxophleba ssp. lissophloia LAS Johnson and KD Hill, or E. kochii ssp. plenissima (CA Gardner) Brooker), various crop and pasture rotations, and various mallee harvest-management treatments. Mallee–crop competition was negatively correlated with rainfall and positively correlated with mallee age and size, and greater for crops than pasture. Consequently, extent and magnitude of competition were highly variable across sites and years. On average, mallee–crop competition extended 11.3 m from unharvested belts and reduced crop and pasture yields by 36% within 2–20 m of the mallee belts relative to open paddock yields. This is similar to what has been reported for taller tree species. Harvesting mallees reduced competition such that crop and pasture yield was reduced by 22 or 27% relative to open paddock yields for mallees harvested at 3- or 6+-year intervals, respectively. The economic cost of mallee–crop competition on agricultural enterprises was also highly variable between sites, and between years within individual sites. Averaged across all site-years, the opportunity cost of competition was equivalent to forgoing agricultural production for 14.4 m on each side of unharvested mallee belts, or 9–10 m on each side of harvested belts. Farmers with mallee agroforestry systems will need to manage the economic impacts of competition by reducing agricultural input costs in the competition zone, timing crop-grazing rotations with mallee harvests, ensuring that the width of alleys is at least 25 times the height of the mature trees, and possibly root-pruning mallees in unharvested or long harvest interval systems. This research has shown that mallee–crop competition presents a significant cost to farmers and must be considered when designing mallee agroforestry systems. The findings have relevance for the development of appropriate biomass and carbon sequestration pricing benchmarks for mallee plantings.

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41

Latta, R. A., e A. Lyons. "The performance of lucerne - wheat rotations on Western Australian duplex soils". Australian Journal of Agricultural Research 57, n. 3 (2006): 335. http://dx.doi.org/10.1071/ar04016.

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Abstract (sommario):

In field experiments on duplex soils in the south-eastern and central Western Australian wheatbelt, lucerne (Medicago sativa L.) was compared with subterranean clover (Trifolium subterraneum L.) in pasture–crop rotations. Comparative pasture plant densities and biomass, soil water content, available soil nitrogen, wheat grain yield, and protein content were measured during 2 and 3 years of pasture followed by 2 and 1 year of wheat, respectively. Lucerne densities declined by 60–90% over the 3-year pasture phase but produced up to 3 times more total annual biomass than weed-dominant annual pastures and similar total annual biomass when annual pastures were legume dominant. Lower soil water contents were measured under lucerne than under annual pastures from 6 months after establishment, with deficits up to 60 mm in the 0–1.6 m soil profile. However, significant rain events and volunteer perennial weeds periodically negated comparative deficits. Wheat yields were lower following lucerne (1.3 t/ha) than following an annual pasture (1.8 t/ha) in a low-rainfall season, higher (3.7 v. 2.9 t/ha) in a high-rainfall season, and much higher when the previous annual pastures were grass dominant (3.4 v. 1.5 t/ha). Grain protein contents were 1–2% higher in response to the lucerne pasture phase. Overcropping wheat into a lucerne pasture of 19 plants/m2 reduced wheat grain yields, but a lucerne density of 4 plants/m2 reduced yields only where rainfall was low. The study has shown that lucerne–wheat rotations provide a productive farming system option on duplex, sodic soils in both the south-eastern and central cropping regions of Western Australia. This was most evident in seasons of above-average summer and growing-season rainfall and when compared with grass-dominant annual pastures.

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42

Riley, MM, JW Gartrell, RF Brennan, J. Hamblin e P. Coates. "Zinc deficiency in wheat and lupins in Western Australia is affected by the source of phosphate fertiliser". Australian Journal of Experimental Agriculture 32, n. 4 (1992): 455. http://dx.doi.org/10.1071/ea9920455.

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Abstract (sommario):

A long-term field experiment is being conducted in the wheatbelt of Western Australia to determine the effects of source of phosphate fertiliser on the residual effectiveness of zinc (Zn) to wheat and to sweet, narrow-leafed lupins grown in rotation. The initial 2 years' results of that experiment reported here indicate that both wheat and lupins responded to the addition of Zn to the soil. The requirements of these crops for Zn, can be mostly met with the small amount of Zn that is a natural component in single superphosphate manufactured from rock phosphates, but not with diammonium phosphate (DAP). The internal requirements for Zn of the aboveground tissues of lupins appear greater than those of wheat. Depending on the stage of growth, critical concentrations of Zn in the youngest leaf tissues of wheat that were prognostic of Zn deficiency, were found to vary from about 7 to 16 �g/g, while those in lupins were found to vary from about 28 to 37 �g/g.

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43

Thompson, R. B., e I. R. P. Fillery. "Fate of urea nitrogen in sheep urine applied to soil at different times of the year in the pasture - wheat rotation in south Western Australia". Australian Journal of Agricultural Research 49, n. 3 (1998): 495. http://dx.doi.org/10.1071/a97097.

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Abstract (sommario):

Sheep urine labelled with 15N-urea was applied toconfined micro-plots at different times of the year to follow the fate of ureaN in urine in the grazed pasture-wheat rotation in south Western Australia.Three field experiments were conducted on the same site on a loamy sand.Applications were made either to pasture residues (Expts 1 and 2) which weresubsequently sown to wheat, orto growing pasture in winter-spring, (Expt 3).In Expt 1, urine was applied in November 1990 (9·8 gN/m2) and April 1991 (46·1 gN/m2). From both applications, losses of15N attributed to NH3volatilisation were c. 50% within 2 weeks of application. Another10% loss was attributed toNO-3 leaching during the followinggrowing season and 15% was recovered by the wheat crop. In Expt 2,urine was applied in October 1991 (4·6 gN/m2), January 1992 (15·6 gN/m2), and March 1992 (13·6 gN/m2). Attributed NH3 losseswithin 2 weeks, in terms of 15N-urea applied, were40% (October and January urine) and 30% (March urine) andNO-3 leaching losses were estimated to be 20% forthe 3 applications. Recoveries in wheat (November 1992) were 4, 7, and12% of 15N applied in the October, January, andMarch urine applications. In Expt 3, urine was applied in August 1992(12·3 g N/m2) and September 1992 (25·9g N/m2). Attributed NH3 losseswere 10% of applied 15N for the August and30% for the September application. Plant uptake of15N was rapid and by mid October was 42% from theAugust application and 47% from the September application. Recovery of15N in soil organic N was generally 17-25% whenurine was applied to pasture residues and bare soil,and 21-37% whenurine was applied to growing pasture. It is suggested thatNH3 volatilisation was the predominant N loss mechanism.The amount of NO-3 leached wasprimarily influenced by summer rainfall, the length of time urine-N was insoil before the onset of winter rainfall, and the distributionof winterrainfall. Little of the 15N-labelled urine was eitherrecovered by, or available for, subsequent wheat crops, suggesting thatcalculations for estimating the N supply from pastures to cereal cropsmustdiscount most N returned in urine by grazing animals.

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44

Gremigni, P., M. W. Sweetingham e W. A. Cowling. "Seed alkaloid concentrations are not affected by agronomic and phosphorus-nutrition treatments that reduce Pleiochaeta setosa Hughes disease on narrow-leafed lupin (Lupinus angustifolius)". Australian Journal of Experimental Agriculture 46, n. 5 (2006): 681. http://dx.doi.org/10.1071/ea05078.

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Abstract (sommario):

The severity of brown spot caused by the fungus Pleiochaeta setosa (Kirchn.) Hughes in narrow-leafed lupin (Lupinus angustifolius L.) is reduced by improving phosphorus (P) nutrition and using agronomic treatments that extend crop rotation or increase cereal stubble retention. The aim of this work was to investigate the impact of these treatments on the alkaloid concentrations of the harvested seed of 3 sweet cultivars of L. angustifolius that differed in their susceptibility to this fungal disease: Merrit (susceptible), Tallerack and Myallie (both moderately resistant). Because abiotic and biotic stresses appear to stimulate plant alkaloid biosynthesis, we hypothesised that higher levels of disease pressure may increase alkaloid concentrations in the harvested seed, particularly in the disease-susceptible Merrit. The main effects of P nutrition, cereal stubble retention, genotype and crop rotation were significant for the severity of brown spot and plant biomass of narrow-leafed lupin in a field trial in Wongan Hills, Western Australia, but were not significant for total alkaloid concentrations or the relative proportions of individual alkaloids of the harvested seed. Seed total alkaloid concentrations were in most cases below the maximum permitted concentration established for lupin seed (200 mg/kg dry matter) and were independent of the severity of brown spot on leaves. The great fluctuations of seed total alkaloid concentrations observed in grower deliveries to bulk handling facilities and in lupin cultivar yield testing trials are unlikely to result from the nutritional and agronomic treatments such as those investigated in this experiment, or the various disease levels that resulted from these treatments.

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45

Nichols, P. G. H., G. A. Sandral, B. S. Dear, C. T. de Koning, D. L. Lloyd, P. M. Evans, A. D. Craig et al. "Izmir subterranean clover (Trifolium subterraneum L. var. subterraneum)". Australian Journal of Experimental Agriculture 47, n. 2 (2007): 226. http://dx.doi.org/10.1071/ea05283.

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Abstract (sommario):

Izmir is a hardseeded, early flowering, subterranean clover of var. subterraneum (Katz. et Morley) Zohary and Heller collected from Turkey and developed by the collaborating organisations of the National Annual Pasture Legume Improvement Program. It is a more hardseeded replacement for Nungarin and best suited to well-drained, moderately acidic soils in areas with a growing season of less than 4.5 months. Izmir seed production and regeneration densities in 3-year pasture phases were similar to Nungarin in 21 trials across southern Australia, but markedly greater in years following a crop or no seed set. Over all measurements, Izmir produced 10% more winter herbage and 7% more spring herbage than Nungarin. Its greater hardseededness and good seed production, makes it better suited to cropping rotations than Nungarin. Softening of Izmir hard seeds occurs later in the summer–autumn period than Nungarin, giving it slightly greater protection from seed losses following false breaks to the season. Izmir is recommended for sowing in Western Australia, New South Wales, Victoria, South Australia and Queensland. Izmir has been granted Plant Breeders Rights in Australia.

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46

Zhang, Xuehua, e W. G. Dilantha Fernando. "Insights into fighting against blackleg disease of Brassica napus in Canada". Crop and Pasture Science 69, n. 1 (2018): 40. http://dx.doi.org/10.1071/cp16401.

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Abstract (sommario):

Blackleg disease, caused by the ascomycete fungal pathogen Leptosphaeria maculans, is a devastating disease of canola (Brassica napus) in Australia, Canada and Europe. Although cultural strategies such as crop rotation, fungicide application, and tillage are adopted to control the disease, the most promising disease control strategy is the utilisation of resistant canola varieties. However, field populations of L. maculans display a high evolutionary potential and are able to overcome major resistance genes within a few years, making disease control relying on resistant varieties challenging. In the early 1990s, blackleg resistance gene Rlm3 was introduced into Canadian canola varieties and provided good resistance against the fungal populations until the early 2000s, when moderate to severe blackleg outbreaks were observed in some areas across western Canada. However, the breakdown of Rlm3 resistance was not reported until recently, based on studies on R genes present in Canadian canola varieties and the avirulence allele frequency in L. maculans populations in western Canada. The fact that Rlm3 was overcome by the evolution of fungal populations demands canola breeding programs in Canada to be prepared to develop canola varieties with diversified and efficient R genes. In addition, frequent monitoring of fungal populations can provide up-to-date guidance for proper resistance genes deployment. This literature review provides insights into the outbreaks and management of blackleg disease in Canada.

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47

Bolland, M. D. A., e R. J. Gilkes. "Evaluation of two rock phosphates and a calcined rock phosphate as maintenance fertilizers for crop ? pasture rotations in Western Australia". Fertilizer Research 28, n. 1 (aprile 1991): 11–24. http://dx.doi.org/10.1007/bf01048851.

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48

Anderson, G. C., I. R. P. Fillery, P. J. Dolling e S. Asseng. "Nitrogen and water flows under pasture - wheat and lupin - wheat rotations in deep sands in Western Australia. 1. Nitrogen fixation in legumes, net N mineralisation,and utilisation of soil-derived nitrogen". Australian Journal of Agricultural Research 49, n. 3 (1998): 329. http://dx.doi.org/10.1071/a97141.

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Abstract (sommario):

Detailed studies on the eciency with which pastures and crops use soil-derived nitrogen (N) in southern Australia are limited. Inefficiencies in the N cycle are indicated by wide spread soilacidification and low N status in wheat grain. The aims of this study were to document rates of N2 fixation by subterranean clover-based pastures and narrow-leaf lupin, plant uptake of soil-derived N, mineralisation of organic N during legume and cereal phases, and export of N from pastures, lupin,and wheat in relation to climate and soil water. These measurements were undertaken in a rotation experiment conducted on a deep sand located in the northern wheat belt of Western Australia at a site with a long-term average rainfall of 460 mm. The rotations examined over 3 years were 2 years pasture-wheat and lupin-wheat. The 15N natural abundance technique was used to differentiate soil-derived N from atmospheric Nin legumes. Biomass production, grain yields, and N contents were standard plant measurements in all treatments. Net N mineralisation between growing seasons was as certained by measuring changes in soil inorganic N to 1·5 m. Growing season net N mineralisation was determined using an in situ method in which soil cores were isolated from plant roots. Anion exchange resin was used to trap NO-3 leached below the depth of the soil cores. Nitrogen fixation by subterranean clover in a mixed pasture ranged from 29 to 162 kg N/ha whereas N2 fixation by lupins was less variable, ranging from 90 to 151 kg N/ha. Pastures were large consumers of soil-derived N (range 58-154 kg N/ha), with capeweed being the most important sink (range 38-120 kg N/ha). In comparison, wheat and lupins were inefficient users of soil N, removing 29-51 kg N/ha within a season. Another 31-67 kg N/ha of inorganic N in soil was not utilised by wheat or lupin. Annual net N mineralisation ranged from 80 to 130 kg N, confirming the high rate of decomposition of organic matter in the sandy soil. Mineralisation over summer and autumn, when crop and pastures were not grown, supplied ~25% of the inorganic N produced in soil profiles in 1995 and 20-40% in1996. The study indicated that legumes used in rotations with cereals on deep sands were able to add adequate organic N to soil to insure rates of net N mineralisation sufficient to support cereal yieldsin excess of current shire averages. However, in practice, the asynchrony in supply and demand for N resulted in the inefficient use of soil-derived N by wheat.

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49

Chapman, D. F., D. Beca, J. Hill, J. Tharmaraj, J. L. Jacobs e B. R. Cullen. "Increasing home-grown forage consumption and profit in non-irrigated dairy systems. 4. Economic performance". Animal Production Science 54, n. 3 (2014): 256. http://dx.doi.org/10.1071/an13186.

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Abstract (sommario):

The profitability of dairy farm systems in southern Australia is closely related to the amount of pasture grown and consumed on-farm by dairy cows. However, there are doubts regarding the extent to which gains in feed supply from perennial ryegrass pasture can continue to support productivity growth in the industry. A farmlet experiment was conducted in south-western Victoria for 4 years (June 2005–May 2009), comparing a production system based on the use of forage species that complement perennial ryegrass in their seasonal growth pattern (‘Complementary Forages’, or CF) with a well managed system solely based on perennial ryegrass pasture (‘Ryegrass Max’, or RM). The forage base in CF included perennial ryegrass with a double-cropping rotation of winter cereal grown for whole-crop silage, followed by a summer brassica for grazing on 15% of farmlet area, a summer-active pasture based on tall fescue (on average 20% of farmlet area), perennial ryegrass oversown with short-rotation ryegrasses (average 16% of farmlet area) and summer brassica crops used in the process of pasture renovation (average 5% of farmlet area). The stocking rate was 2.2 and 2.8 cows/ha on RM and CF, respectively. Both systems were profitable over the 4 years of the experiment, with the modified internal rate of return over 4 years being 14.4% and 14.7% for the RM and CF farmlets, respectively. The coefficient of variation (%) of annual operating profit over 4 years was higher for the CF farmlet (56% and 63% for RM and CF, respectively). A severe drought in one of the 4 years exposed the more highly stocked CF system to greater supplementary feed costs and business risk. By comparison, the RM system performed consistently well across different seasons and in the face of a range of milk prices. The very small gain in profit from CF, plus the associated higher risk, makes it difficult to endorse a substantial change away from the traditional RM feed supply to greater reliance on summer-grown forages on non-irrigated dairy farms in southern Australia, as implemented in this experiment.

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50

Brennan, R. F., e M. D. A. Bolland. "Comparing copper requirements of field pea and wheat grown on alkaline soils". Australian Journal of Experimental Agriculture 44, n. 9 (2004): 913. http://dx.doi.org/10.1071/ea03091.

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Abstract (sommario):

Copper (Cu) is a common deficiency of spring wheat (Triticum aestivum L.), the major crop grown in south-western Australia. The Cu requirements of wheat are well known for soils in the region, but are not known for field pea (Pisum sativum L.) grown in rotation with wheat on alkaline soils in the region. The Cu requirements of field pea and spring wheat were compared in a glasshouse experiment, using 2 alkaline soils from south-western Australia. The Cu was either incubated in moist soil at 22°C for 100 days before sowing (incubated Cu) or applied just before sowing (current Cu). Comparative Cu requirements were determined from yields of 43-day-old dried shoots for: (i) Cu already present in the soil (indigenous Cu); (ii) the amount of added Cu required to produce the same percentage of the maximum (relative) yield of dried shoots; and (iii) the Cu content of dried shoots (Cu concentration multiplied by yield of dried shoots). The critical concentrations of Cu in youngest mature growth and in dried shoots were also determined. As determined from yield of shoots, both species used indigenous Cu about equally effectively. Compared with spring wheat, field pea was about 12% less effective at using current and incubated Cu to produce dried shoots. It was about 15% less effective at using current and incubated Cu to increase Cu content in dried shoots. Relative to current Cu, the effectiveness of incubated Cu declined by about 60% for both wheat and field pea in both soils. The critical Cu concentration in the youngest tissue, associated with 90% of the relative yield, was 1.4 mg Cu/kg for spring wheat and 2.0 mg Cu/kg for field pea. The critical value for the rest of the dried shoots was about 3.0 mg Cu/kg for both species.

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