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Journal articles on the topic 'Soil phosphorus'
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1
Shah, Asad, Jing Huang, Muhammad Numan Khan, Tianfu Han, Sehrish Ali, Nano Alemu Daba, Jiangxue Du, et al. "Sole and Combined Application of Phosphorus and Glucose and Its Influence on Greenhouse Gas Emissions and Microbial Biomass in Paddy Soils." Agronomy 12, no. 10 (September 30, 2022): 2368. http://dx.doi.org/10.3390/agronomy12102368.
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Soil microbial activities are consistently restricted not only by phosphorus availability but also by microbial carbon requirements. Therefore, an incubation experiment was conducted with three soils (QY1, QY2 and QY3) selected on the basis of phosphorus limitation. Results revealed that high N2O emissions, 17.44 µg kg−1, were measured in phosphorus-deficient soil with addition of glucose. In phosphorus-adequate soils, the peaks of N2O emission values in the glucose addition treatment were 20.8 µg kg−d and 24.7 µg kg−1, which were higher than without glucose-added treatments. CH4 emissions were higher with glucose addition, at 1.9 µg kg−e in phosphorus-deficient soil and 1.52 µg kg−e and 2.6 µg kg−1 in two phosphorus-adequate soils. Phosphorus added to deficient and adequate soil significantly increased the cumulative CH4 and N2O emissions compared to the solely glucose added soil and the combination of glucose with phosphorus. Glucose addition significantly increased microbial biomass carbon (MBC) but decreased microbial biomass phosphorus (MBP), especially in the phosphorus-adequate soil. For MBC, the highest value obtained was 175.8 mg kg−1, which was determined under glucose addition in phosphorus-adequate soil. The soil pH increased with glucose addition but decreased with phosphorus addition in phosphorus-deficient soil. The soil organic carbon (SOC) content was significantly affected by glucose addition in the phosphorus-deficient soil. Available phosphorus (AP) was highly influenced by phosphorus addition but did not appear to be affected by glucose addition. From the current study, we concluded that sole phosphorus and glucose addition increase CH4 andN2O emissions in phosphorus-deficient and also in phosphorus-adequate paddy soils. Further study will be conducted on sole and interactive effects of glucose and phosphorous on soil with plants and without plants.
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Xu, Gang, Mengyu Yue, Jiawei Song, and Xiaobing Chen. "Development of soil phosphorus storage capacity for phosphorus retention/release assessment in neutral or alkaline soils." Plant, Soil and Environment 68, No. 3 (March 16, 2022): 146–54. http://dx.doi.org/10.17221/482/2021-pse.
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The concept of the soil phosphorus storage capacity (SPSC) was successfully used to evaluate the phosphorus (P) loss risk and the P retention capacity of acidic soil. This study extended the concept of SPSC from acidic soil to neutral or alkaline soil. A total of 95 surfaces (0–10 cm) soil samples were collected from the Yellow River Delta (YRD) for use in this study. Batch sorption experiments, correlation analysis, stepwise regression, and a split-line model were used to calculate the threshold value of the degree of P saturation (DPS). The SPSC was developed based on the DPS threshold value. Based on a DPS threshold value of 11.5%, we developed the following equation for calculating the SPSC: SPSC = (11.5% – soil DPS) × (0.113 × SOM (soil organic matter) + 1.343 × CaCO<sub>3</sub>). In the continuous system in this watershed, from wetland to farmland, the SPSC for vegetable fields (−94.7 ± 79.1 mg/kg) was lowest and that of the restored wetland (76.3 ± 26.1 mg/kg) was the highest. Along the transition zone in the YRD, both the natural soil development and human alternations significantly affected the soil P loss/retention capacity. In terms of P storage, the restored wetlands are the highlands for P retention and the vegetable fields contribute significantly to the P loss in the YRD. As a result, we strongly recommend that the restored wetlands be fully utilised for P retention and that P fertiliser no longer be applied to the vegetable fields to prevent P loss into the watershed.
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Matula, J. "Relationship between phosphorus concentration in soil solution and phosphorus in shoots of barley." Plant, Soil and Environment 57, No. 7 (July 14, 2011): 307–14. http://dx.doi.org/10.17221/149/2011-pse.
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Phosphorus concentration in the soil solution of agricultural soils should be a consensus of the agronomic and environmental aspect. Data from literary sources are inconsistent if the method of soil solution extraction from the soil and the method of phosphorus detection are not indicated. In the present paper a simplified procedure of soil solution extraction is used that is derived from the need of water to attain saturated soil paste. Based on barley cultivation in a plant growth chamber on 72 different soils the relationship between P concentration in simulated soil solution and the response of test plant (spring barley) was evaluated. Three approaches were used to derive an adequate P concentration in soil solution. Based on the diagnostics of P content in barley the following adequate P concentrations in soil solution were derived: 0.23–0.86 ppm P for colorimetry and 0.9–1.75 ppm P for ICP-AES. Using the concept of the boundary line of yield the critical P concentration in soil solutions was 0.8 ppm P for colorimetry and 1.3 ppm P for ICP-AES. The concept of the boundary line of P efficiency index enabled to define P concentrations in soil solution that can be considered as the lower limits of suitability from the agronomic aspect:<br />0.15 ppm P in simulated soil solution for colorimetry and 0.7 ppm P for ICP-AES.
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Sánchez-Esteva, Sara, Maria Knadel, Rodrigo Labouriau, Gitte H. Rubæk, and Goswin Heckrath. "Total Phosphorus Determination in Soils Using Laser-Induced Breakdown Spectroscopy: Evaluating Different Sources of Matrix Effects." Applied Spectroscopy 75, no. 1 (August 24, 2020): 22–33. http://dx.doi.org/10.1177/0003702820949560.
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Laser-induced breakdown spectroscopy (LIBS) is a potential alternative to wet chemical methods for total soil phosphorus determination, but matrix effects related to physical and chemical sample properties need to be further understood. The aim of this study was to explore matrix effects linked to particle size distribution and chemical form of phosphorus on LIBS response and the ability of LIBS to predict total phosphorus in a range of different soil types. Univariate calibration curves were developed by spiking the soils with increasing doses of phosphorus, and limits of detection for LIBS determined phosphorous (P) (LIBS-P) were calculated. Different particle size distributions in otherwise identical soils were obtained by four milling treatments and effects of chemical form of phosphorus were examined by spiking soils with identical amounts of phosphorus in different chemical compounds. The LIBS-P response showed a high correlation (R2 > 0.99) with total phosphorus for all soils. Yet, the sensitivity of LIBS differed significantly among soils, as the slope of the calibration curves increased with increasing sand content, resulting in estimated limits of detection of 10 mg kg−1 for the sandiest and 122 mg · kg−1 for the most clayey soils. These limits indicate that quantitative evaluation of total phosphorus in sandy and loamy sandy soils by LIBS is feasible, since they are lower than typical total phosphorus concentrations in soil. A given milling treatment created different particle size distributions depending on soil type, and consequently different LIBS-P results. Thus, procedures that specify the required degree of homogenization of soil samples prior to analysis are needed. Sieving after milling could be an option, but that should be tested. The soils spiked with Fe(III) phosphate, potassium phosphate and phytic acid had similar LIBS-P, except for soils with hydroxyapatite, which resulted in markedly lower response. These results suggested that matrix effects related to the chemical nature of phosphorus would be minor for non-calcareous soils in humid regions, where apatites comprise only a small fraction of total phosphorus. Strategies to overcome matrix effects related to particle size and content of apatite-phosphorus by combining multivariate models and soil type groupings should be further investigated.
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Adil, Mihoub. "Citric acid acidification of wheat straw derived biochar for overcoming nutrient deficiency in alkaline calcareous soil (Case of Phosphorus)." International Journal of Agricultural Science and Food Technology 8, no. 3 (August 27, 2022): 248–52. http://dx.doi.org/10.17352/2455-815x.000173.
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Phosphorous fixation in soils is a serious concern worldwide, and biochar is gaining attention daily due to its potential benefits for improving the agronomic benefits of applied phosphorus. The present study aims to enhance understanding of the phosphorus transformation process in a deprived sandy soil following biochar amendments (no-acidified wheat straw biochar and chemically modified (acidification with 0.01 M C6H8O7) along with or without phosphorus at 250 mg kg−1. A 54-day pot experiment was conducted with two biochar levels of 4%, 8% (w/w), and control, and two phosphorus levels (without or with phosphorus). The results indicate that the integration of acidified wheat straw biochar with phosphorus resulted in increased available phosphorus in the soil. We conclude that incorporating acidified wheat straw biochar is a promising practice to potentially improve phosphorus availability in deprived soils. Further research is needed to explore site-specific phosphorus management for sustainable crop production.
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McKenzie, R. H., and E. Bremer. "Relationship of soil phosphorus fractions to phosphorus soil tests and fertilizer response." Canadian Journal of Soil Science 83, no. 4 (August 1, 2003): 443–49. http://dx.doi.org/10.4141/s02-079.
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Soil tests for available P may not be accurate because they do not measure the appropriate P fraction in soil. A sequential extraction technique (modified Hedley method) was used to determine if soil test P methods were accurately assessing available pools and if predictions of fertilizer response could be improved by the inclusion of other soil P fractions. A total of 145 soils were analyzed from field P fertilizer experiments conducted across Alberta from 1991 to 1993. Inorganic P (Pi) removed by extraction with an anion-exchange resin (resin P) was highly correlated with the Olsen and Kelowna-type soil test P methods and had a similar relationship with P fertilizer response. No appreciable improvement in the fit of available P with P fertilizer response was achieved by including any of the less available P fractions in the regression of P fertilizer response with available P. Little Pi was extractable in alkaline solutions (bicarbonate and NaOH), particularly in soils from the Brown and Dark Brown soil zones. Alkaline fractions were the most closely related to resin P, but the relationship depended on soil zone. Inorganic P extractable in dilute HCl was most strongly correlated with soil pH, reflecting accumulation in calcareous soils, while Pi extractable in concentrated acids (HCl and H2SO4) was most strongly correlated with clay concentration. A positive but weak relationship as observed between these fractions and resin P. Complete fractionation of soil P confirmed that soil test P methods were assessing exchangeable, plant-available P. Key words: Hedley phosphorus fractionation, resin, Olsen, Kelowna
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Benhua, Sun, Cui Quanhong, Guo Yun, Yang Xueyun, Zhang Shulan, Gao Mingxia, and Hopkins David W. "Soil phosphorus and relationship to phosphorus balance under long-term fertilization." Plant, Soil and Environment 64, No. 5 (May 14, 2018): 214–20. http://dx.doi.org/10.17221/709/2017-pse.
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Temporal changes in the concentrations of plant-available phosphorus (P) in soil (Olsen-P), total soil-P and P activation coefficient (the ratio of Olsen-P to residual-P (i.e. an approximation to total-P)) were measured in plots that received consistent inorganic nitrogen, phosphorus and potassium plus organic fertilizers annually. Maize and winter wheat crops were grown in rotation for 24 years. Olsen-P and P activation coefficient declined significantly in the earlier years (< 12 years) for treatments that did not include any P fertilizer, and increased over the same period for the P-fertilized treatments. The rates of change in the Olsen-P and P activation coefficient values were positively related to P balance. In the later years, the Olsen-P and P activation coefficient plateau values were positively related to the P balance.
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UUSITALO, R., E. TURTOLA, and J. GRÖNROOS. "Finnish trends in phosphorus balances and soil test phosphorus." Agricultural and Food Science 16, no. 4 (December 4, 2008): 301. http://dx.doi.org/10.2137/145960607784125339.
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Soil test phosphorus (P) concentration has a major influence on the dissolved P concentration in runoff from agricultural soils. Thus, trends in soil test P partly determine the development of pollution potential of agricultural activities. We reviewed the changes of soil test P and P balances in Finnish agriculture, and assessed the current setting of P loss potential after two Agri-Environmental Programs. Phosphorus balance of the Finnish agriculture has decreased from +35 kg ha1 of the 1980s to about +8 kg P ha1 today. As a consequence, the 50-yr upward trend in soil test P concentrations has probably levelled out in the late 1990s, as suggested by sampling of about 1600 fields and by a modelling exercise. For the majority of our agricultural soils, soil test P concentrations are currently at a level at which annual P fertilization is unlikely to give measurable yield responses. Soils that benefit from annual P applications are more often found in farms specialized in cereal production, whereas farms specialized in non-cereal plant production and animal production have higher soil test P concentrations. An imbalance in P cycling between plant (feed) and animal production is obvious, and regional imbalances are a result of concentration of animal farms in some parts of the country. A major concern in future will be the fate of manure P in those regions where animal production intensity is further increasing.;
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Lei, Hong Jun, Xin Liu, Bei Dou Xi, and Duan Wei Zhu. "Evaluation on a Novel Phosphorus Fractionation Method in Acid Soils." Applied Mechanics and Materials 204-208 (October 2012): 272–78. http://dx.doi.org/10.4028/www.scientific.net/amm.204-208.272.
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Phosphorous fractionation is a method developed to estimate sizes of readily soil available P pool, soil P sub-pools and their ability to replenish the available P. Three types of acid soils (1aterite red soil, yellow red soil and brown red soil) were used in pot experiment under a rain-shelter condition to investigate the effect of lime amendment on P fractions and their bioavailability by plant of broad bean. A novel phosphorus fractionation scheme was developed and used to study the phosphorus fractionation of the tested soils compared with the two typical soil phosphorus fractionation schemes, adopting a series of extractants such as 0.25mol L-1 NaHCO3, 1h (for Ca2-P), 0.5mol L-1 NH4F (pH8.5), 1h (for Al-P), 0.7mol L-1 NaClO, pH 8.05, 85°C water bath 30min (for Org-P), 0.1mol L-1 NaOH-0.1Na2CO3, 4h (for Fe-P), 1mol L-1 NaOH, 85°C water bath 1h (for O-Al-P), 0.3 mol L-1 Na-citrate-0.5 g Na2S2O4 -0.5 mol L-1 NaOH, 85°C water bath 15min (for O-Fe-P), 0.25mol L-1 H2SO4, 1h (for Ca10-P). Main results are obtained just as follows: besides Ca2-P, Al-P, Fe-P and O-Fe-P are potentially available phosphorus resource. Although O-P reflects the difference of P between lime and control treatment well, when it appears as a whole, it needs further subdivision to reflect soil phosphorus biologically availability difference better.
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Bhodiwal, Shweta, and Tansukh Barupal. "Phosphate solubilizing microbes: an incredible role for plant supplements." MOJ Ecology & Environmental Sciences 7, no. 5 (December 21, 2022): 170–72. http://dx.doi.org/10.15406/mojes.2022.07.00263.
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Plants procure phosphorus from soil as the phosphate anion. It is the most un-portable component in plant and soil in comparison to other macronutrients. It’s very well known that phosphorus is the second most significant supplement after the nitrogen required/needed in plant growth. It is a fundamental component in every single living system. Barely 1%-2% of phosphorous is provided to different parts of the plants. It precipitates in soil as orthophosphate or is adsorbed by Fe and Al oxides through legend exchange. Phosphorus-solubilizing bacteria play a substantial part in phosphorus nutrition by increasing phosphorus' accessibility to plants through discharge from inorganic and natural soil P pools by solubilization and mineralization. Lowering the pH of the soil through microbial generation of natural acids and mineralization of natural phosphorus by acid phosphates is the key element in the soil for mineral phosphate solubilization. Chemical composts are used as an additional source of phosphorous to satisfy the plant’s need. Additionally, co-inoculating P solubilizing microorganisms with other beneficial bacteria and mycorrhiza has shown to increase their efficiency. Microbial inoculants or biofertilizers can thus be used as an alternative source because they are both economical and environmentally favourable.
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Szara, Ewa, Tomasz Sosulski, and Magdalena Szymańska. "Soil phosphorus sorption properties in different fertilization systems." Plant, Soil and Environment 65, No. 2 (February 1, 2019): 78–82. http://dx.doi.org/10.17221/696/2018-pse.
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The study aimed at the evaluation of the accumulation and vertical distribution of different forms of phosphorus (P) in reference to phosphorus sorption properties subject to mineral (NPK), mineral-organic (NPK + M), and organic (M) fertilisation. It was carried out in a long-term experimental field in Skierniewice (Central Poland) conducted since 1923 under rye monoculture. Total P content in the M and NPK soil profile was similar and lower than in the NPK + M soil. The content of organic P in A<sub>p</sub> and E<sub>et</sub> horizons of both manured soils was similar and higher than in the NPK soil. The Langmuir P sorption maximum (S<sub>max</sub>) in the studied soils ranged from 39.7 to 90 mg P/kg, while the Freundlich P sorption coefficient a<sub>F</sub> ranged from 6.9 to 41.9 mg P/kg. Higher variability of parameters related to the binding energy from the Lanqmuir (k) and Freundlich (a<sub>F</sub>) equations was determined between soil horizons than between the fertilisation systems. Nonetheless, in M and NPK + M soils, sorption parameters a<sub>F</sub> and S<sub>max</sub> and binding energy (k, b<sub>F</sub>) were considerably lower than in the NPK soil. The content of water extracted P in manured soils was higher than in the NPK soil.
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Xu, G., J. N. Sun, R. F. Xu, Y. C. Lv, H. B. Shao, K. Yan, L. H. Zhang, and M. S. A. Blackwell. "Effects of air-drying and freezing on phosphorus fractions in soils with different organic matter contents." Plant, Soil and Environment 57, No. 5 (May 16, 2011): 228–34. http://dx.doi.org/10.17221/428/2010-pse.
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Little is known about the effects of air-drying and freezing on the transformation of phosphorus (P) fractions in soils. It is important that the way in which soils respond to such perturbations is better understood as there are implications for both P availability and loss to surface waters from soils. In this study, the effects of air-drying and freezing were investigated using two soils, one being a forest soil (FS) high in organic matter and the other being a sterile soil (SS) low in organic matter. Soil P was fractionated using a modified Hedley fractionation method to examine the changes of phosphorus fractions induced by air-drying and freezing. Generally, there were no significant differences of total phosphorus among the three treatments (CV% < 10%). Compared with field moist soils, freezing the soil evoked few changes on phosphorus fractions except that the resin-P increased in FS soil. On the contrary, air-drying significantly changed the distribution of phosphors fractions for both soils: increased the labile-P (especially resin-P) and organic-P (NaHCO<sub>3</sub>-Po, NaOH-Po and Con.HCl-Po) at the expense of NaOH-Pi and occlude-P (Dil.HCl-P and Con.HCl-Pi). Resin-P significantly increased by 31% for SS soil and by 121% for FS soil upon air-drying. The effect of air-drying seemed to be more pronounced in the FS soil with high organic matter content. These results indicated that drying seem to drive the P transformation form occlude-P to labile-P and organic-P and accelerated the weathering of stable P pool. This potentially could be significant for soil P supply to plants and P losses from soils to surface waters under changing patterns of rainfall and temperature as predicted by some climate change scenarios.
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Prasad, Vishal, Shivani Chaudhary, and Anjali Singh. "Improving Phosphorus Fertility in Soil through Microbial Mediators." INTERNATIONAL JOURNAL OF PLANT AND ENVIRONMENT 4, no. 02 (July 31, 2018): 74–80. http://dx.doi.org/10.18811/ijpen.v4i02.9.
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Microbes are an important element of the phosphorus cycle operative in the soil and play significant roles in transference of phosphorus between various soil phosphorus pools. Therefore, there has been continued interest in the usage of soil microbes to improve the phosphorus nutrition of plants and increase the overall efficiency of phosphorus use in agricultural systems. This interest originates from the fact that insufficiency of phosphorus is a common problem in soils all over the world, that a foremost cost for agricultural production is due to phosphate fertilizers and that the efficacy of phosphorus used by plants from soil applied phosphate fertilizers is very poor. Hence, with such issues the role of soil microbes in increasing phosphorus fertility in soils becomes more important. In this review several such aspects concerning the solubilisation and mobilization of soil phosphorus by microorganisms for enhancing soil fertility are discussed.
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Σικαλίδης, Κ., and Ν. Καραγιαννίδης. "UTILIZATION OF MINERAL RAW MATERIALS (INDUSTRIAL BYPRODUCTS) AND THEIR MIXTURES AS SOIL PH AMENDMENTS." Bulletin of the Geological Society of Greece 36, no. 1 (January 1, 2004): 43. http://dx.doi.org/10.12681/bgsg.16558.
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Limestone, dolomitic stone, huntite, active magnesia and their mixtures as well as phosphorus containing gypsum, all by-products of various industrial activities, were investigated as soil amendments for acidic (pH 4.2 - 4.5) soils from Drama area, N. Greece and alkaline (pH 8.1 - 8.2) soils from Thermi area, N. Greece. Additions of 500 and 350 kg of the industrial by-products or their various mixtures tested, per 1000 sq.meters, improve the soil pH from the strong acidic area to 6.5- 7.5. Active magnesia increases the pH values above 8. Additions of 200 kg of mixtures of limestone and active magnesia per 1000 sq.meters, found to be able to increase the soil pH from 4.2 to around 6.5. These results were obtained within ten days from the day of application. Phosphorous containing gypsum, by-product of phosphoric fertilizers industry, was found to be able to decrease the soil pH from 8.1-8.2 down to 7.1. The results of this work suggest the possible use of the studied by-products as soil amendments for acidic and alkaline soils, respectively.
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Moody, Philip W., Simon D. Speirs, Brendan J. Scott, and Sean D. Mason. "Soil phosphorus tests I: What soil phosphorus pools and processes do they measure?" Crop and Pasture Science 64, no. 5 (2013): 461. http://dx.doi.org/10.1071/cp13112.
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The phosphorus (P) status of 535 surface soils from all states of Australia was assessed using the following soil P tests: Colwell-P (0.5 m NaHCO3), Olsen-P (0.5 m NaHCO3), BSES-P (0.005 m H2SO4), and Mehlich 3-P (0.2 m CH3COOH + 0.25 m NH4NO3 + 0.015 m NH4F + 0.013 m HNO3 + 0.001 m EDTA). Results were correlated with soil P assays selected to estimate the following: soil solution P concentration (i.e. 0.01 m CaCl2 extractable P; Colwell-P/P buffer index); rate of P supply to the soil solution (i.e. P released to FeO-impregnated filter paper); sorbed P (i.e. Colwell-P); mineral P (i.e. fertiliser reaction products and/or soil P minerals estimated as BSES-P minus Colwell-P); the diffusive supply of P (i.e. P diffusing through a thin gel film, DGT-P); and P buffer capacity (i.e. single-point P buffer index corrected for Colwell-P, PBICol). Across all soils, Colwell-P and BSES-P were highly correlated with FeO-P (r = 0.76 and 0.58, respectively). Colwell-P was moderately correlated with mineral P (r = 0.24), but not solution P. Olsen-P and Mehlich-P were both highly correlated with FeO-P (r = 0.80 and 0.78, respectively) but, in contrast to Colwell-P and BSES-P, also showed moderate correlations with soil solution P (r = 0.29 and 0.34, respectively) and diffusive P supply (r = 0.31 and 0.49, respectively). Correlation coefficients with mineral P were r = 0.29 for Olsen-P and r = 0.17 for Mehlich-P. Soils were categorised according to their pH, clay activity ratio, content of mineral P and CaCO3 content, and the relationships between the empirical soil P tests examined for each soil category. Olsen-P and Colwell-P were correlated across all soil categories (r range 0.66–0.90), and a widely applicable linear equation was obtained for converting one soil test to the other. However, the correlations between other soil tests varied markedly between soil categories and it was not possible to develop such widely applicable conversion equations. Multiple step-up linear regressions were used to identify the key soil properties affecting soil solution P, P buffer capacity, and diffusive P supply, respectively. For all soil categories, solution P concentration (measured by CaCl2-P) increased as rate of P supply (measured as FeO-P) increased and P buffer capacity decreased. As an assay of sorbed P, Colwell-P alone did not significantly (P > 0.05) explain any of the variability in soil solution P, but when used in the index (Colwell-P/P buffer index), it was highly correlated (r = 0.74) with CaCl2-P. Soil P buffer capacity was dependent on different properties in different soil categories, with 45–65% of the variation in PBI accounted for by various combinations of Mehlich-Al, Mehlich-Fe, total organic C, clay content, clay activity ratio, and CaCO3 content, depending on soil category. The diffusive supply of P was primarily determined by rate of P supply (measured as FeO-P; r range 0.34–0.49), with significant (P < 0.05) small improvements due to the inclusion of PBICol and/or clay content, depending on soil category. For these surface soil samples, key properties of pH, clay activity ratio, clay content, and P buffer capacity varied so widely within individual Australian Soil Orders that soil classification was not useful for inferring intrinsic surface soil P properties such as P buffer capacity or the relationships between soil P tests.
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Dodd, R. J., R. W. McDowell, and L. M. Condron. "Changes in soil phosphorus availability and potential phosphorus loss following cessation of phosphorus fertiliser inputs." Soil Research 51, no. 5 (2013): 427. http://dx.doi.org/10.1071/sr13168.
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Long-term application of phosphorus (P) fertilisers to agricultural soils can lead to in the accumulation of P in soil. Determining the rate of decline in soil P following the cessation of P fertiliser inputs is critical to evaluating the potential for reducing P loss to surface waters. The aim of this study was to use isotope exchange kinetics to investigate the rate of decline in soil P pools and the distribution of P within these pools in grazed grassland soils following a halt to P fertiliser application. Soils were sourced from three long-term grassland trials in New Zealand, two of which were managed as sheep-grazed pasture and one where the grass was regularly cut and removed. There was no significant change in total soil P over the duration of each trial between any of the treatments, although there was a significant decrease in total inorganic P on two of the sites accompanied by an increase in the organic P pool, suggesting that over time P was becoming occluded within organic matter, reducing the plant availability. An equation was generated using the soil-P concentration exchangeable within 1 min (E1 min) and P retention of the soil to predict the time it would take for the water-extractable P (WEP) concentration to decline to a target value protective of water quality. This was compared with a similar equation generated in the previous study, which used the initial Olsen-P concentration and P retention as a predictor. The use of E1 min in place of Olsen-P did not greatly improve the fit of the model, and we suggest that the use of Olsen-P is sufficient to predict the rate of decline in WEP. Conversely, pasture production data, available for one of the trial sites, suggest that E1 min may be a better predictor of dry matter yield than Olsen-P.
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Haque, Shama E. "How Effective Are Existing Phosphorus Management Strategies in Mitigating Surface Water Quality Problems in the U.S.?" Sustainability 13, no. 12 (June 9, 2021): 6565. http://dx.doi.org/10.3390/su13126565.
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Phosphorus is an essential component of modern agriculture. Long-term land application of phosphorous-enriched fertilizers and animal manure leads to phosphorus accumulation in soil that may become susceptible to mobilization via erosion, surface runoff and subsurface leaching. Globally, highly water-soluble phosphorus fertilizers used in agriculture have contributed to eutrophication and hypoxia in surface waters. This paper provides an overview of the literature relevant to the advances in phosphorous management strategies and surface water quality problems in the U.S. Over the past several decades, significant advances have been made to control phosphorus discharge into surface water bodies of the U.S. However, the current use of phosphorus remains inefficient at various stages of its life cycle, and phosphorus continues to remain a widespread problem in many water bodies, including the Gulf of Mexico and Lake Erie. In particular, the Midwestern Corn Belt region of the U.S. is a hotspot of phosphorous fertilization that has resulted in a net positive soil phosphorous balance. The runoff of phosphorous has resulted in dense blooms of toxic, odor-causing phytoplankton that deteriorate water quality. In the past, considerable attention was focused on improving the water quality of freshwater bodies and estuaries by reducing inputs of phosphorus alone. However, new research suggests that strategies controlling the two main nutrients, phosphorus and nitrogen, are more effective in the management of eutrophication. There is no specific solution to solving phosphorus pollution of water resources; however, sustainable management of phosphorus requires an integrated approach combining at least a reduction in consumption levels, source management, more specific regime-based nutrient criteria, routine soil fertility evaluation and recommendations, transport management, as well as the development of extensive phosphorus recovery and recycling programs.
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Ebeling, Angela M., Leslie R. Cooperband, and Larry G. Bundy. "Phosphorus Source Effects on Soil Test Phosphorus and Forms of Phosphorus in Soil." Communications in Soil Science and Plant Analysis 34, no. 13-14 (August 2003): 1897–917. http://dx.doi.org/10.1081/css-120023226.
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Pautler, Maria C., and J. Thomas Sims. "Relationships Between Soil Test Phosphorus, Soluble Phosphorus, and Phosphorus Saturation in Delaware Soils." Soil Science Society of America Journal 64, no. 2 (March 2000): 765–73. http://dx.doi.org/10.2136/sssaj2000.642765x.
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Danilova, A. A. "Optimal doses of phosphorous fertilizers (soil biochemical aspects of the problem)." Siberian Herald of Agricultural Science 49, no. 3 (July 23, 2019): 5–15. http://dx.doi.org/10.26898/0370-8799-2019-3-1.
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At present, the problem of supplying soils of Siberia with phosphorus has become much more acute in comparison with the past decades. This is due to virtually complete termination of the use of phosphate fertilizers for grain crops and a sharp increase in the price of these fertilizers compared to the price of grain. There are various approaches to diagnosing the pool of phosphorus available to plants, including methods based on the use of phosphatase preparations allowing to assess the mobility of organic phosphorous compounds in the soil. The content of biologically available soil phosphorus was assessed in the leached chernozem of Priobye, depending on the type of crop rotation and the use of phosphate fertilizers, with the aim of fi nding optimal doses of these fertilizers. After fi ve rotations of three-fi eld grain-fallow crop rotations, the fraction of biologically available soil phosphorus was not detected against the background of no fertilizers or with application of low doses of phosphorus (P15). A certain reserve of phosphorus in the soil was found with the annual use of P60 on the grain-grass crop rotation and long-term application of manure on the farm crop rotation. It was concluded that in the forest-steppe of Priobye, the supply of plants with phosphorus can occur without the formation of biologically available soil phosphorus reserves, whereby the dose of phosphate fertilizer P15 compensates for the annual removal of the element with grain in the average multiyear cycle of years with different climate conditions. Annual application of P60 forms reserves of surplus phosphorus in the form of its biologically available fraction, which makes the economic effi ciency of this doze of the fertilizer questionable.
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Zhang, Jinxin, Liangmin Gao, Zhendong Pang, Linghan Liu, Xiaoqing Chen, Shuo Wang, Hui Wang, Rongrong Tong, Chuang Shi, and Xudong Chen. "Effect of low-molecular-weight organic acids on phosphorus soil activation: A laboratory study of the soils from Wangbeng section of the Huaihe River Basin, China." Plant, Soil and Environment 67, No. 11 (November 24, 2021): 660–67. http://dx.doi.org/10.17221/379/2021-pse.
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Farmland soil samples from the northern and southern banks of the Wangbeng section of the Huaihe River Basin, China, were collected and treated with three different low-molecular-weight organic acids (LMWOAs) (malic acid, citric acid, oxalic acid). This study aimed to determine how these acids affect soil phosphorus activation. The results showed that the average activation rate of total phosphorus, inorganic phosphorus, Fe/Al-P and Ca-P in soil samples from the southern bank treated with malic and citric acid was above 162%, except for organic phosphorus, with the highest at 192.04%. The three organic acids displayed significantly greater phosphorus activation in the northern bank soil samples than those of the southern bank. However, the overall average activation rate in the northern bank soils was lower than that of the southern bank. The four factors of phosphorus species, acid species, acid concentration, and treatment time had significant effects on phosphorus activation in the soils from both banks. This study showed that the three organic acids significantly activated inert phosphorus in the soil. Among them, malic acid and citric acid had a stronger effect on activating soil phosphorus and increased the available soil phosphorus utilisation rate.
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Zhao, Ya Jie, Xin Chen, Yi Shi, Cai Yan Lu, Bin Huang, and Mu Qiu Zhao. "Impact of Fertilization and Soil Phosphorus Status on Phosphorus Leaching from Soil in Vegetable Greenhouse." Advanced Materials Research 610-613 (December 2012): 2968–73. http://dx.doi.org/10.4028/www.scientific.net/amr.610-613.2968.
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The vegetable utilization rate of phosphorus fertilizer in greenhouse condition was low in the season of fertilizer application, resulting in phosphorus accumulation in the top soil year after year. The risk of phosphorus loss through leaching increased under the circumstance of inappropriate watering management and fertilization. In this study, leaching experiments using columns packed with a greenhouse soil with different soil phosphorus status (low, medium and high levels) were carried out under greenhouse condition to investigate the impact of fertilizer application on phosphorus leaching from greenhouse soil. The fertilization treatments included no fertilizer [CK], organic manure and chemical fertilizer [M+NPK], organic manure [M], chemical fertilizer [NPK]. The vertical migration and leaching loss of soil phosphorus were measured. Results were as follows: (1) total phosphorus (TP) content increased with the extension of leaching time. In the low-level- and medium-level-phosphorus greenhouse soils, TP concentration in the effluent increased with the application of manure; (2) In the high-level-phosphorus greenhouse soil, phosphorus in the effluent from the treatment with the use of fertilizer was the highest TP, with accumulative leaching amount of 2.85 mg in 51 days. The leaching of phosphorus became small after 36 days of leaching experiment. Our study showed that application of manure and chemical fertilizer at proper rates according to soil phosphorus status is beneficial to reduce the leaching loss of phosphorus to the environment.
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Rosolem, Ciro Antonio, and Alexandre Merlin. "Soil phosphorus availability and soybean response to phosphorus starter fertilizer." Revista Brasileira de Ciência do Solo 38, no. 5 (October 2014): 1487–95. http://dx.doi.org/10.1590/s0100-06832014000500014.
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Phosphorus fixation in tropical soils may decrease under no-till. In this case, P fertilizer could be surface-spread, which would improve farm operations by decreasing the time spend in reloading the planter with fertilizers. In the long term, less soluble P sources could be viable. In this experiment, the effect of surface-broadcast P fertilization with both soluble and reactive phosphates on soil P forms and availability to soybean was studied with or without fertilization with soluble P in the planting furrow in a long-term experiment in which soybean was grown in rotation with Ruzigrass (Brachiaria ruziziensis). No P or 80 kg ha-1 of P2O5 in the form of triple superphosphate or Arad reactive rock phosphate was applied on the surface of a soil with variable P fertilization history. Soil samples were taken to a depth of 60 cm and soil P was fractionated. Soybean was grown with 0, 30, and 60 kg ha-1 of P2O5 in the form of triple phosphate applied in the seed furrow. Both fertilizers applied increased available P in the uppermost soil layers and the moderately labile organic and inorganic forms of P in the soil profile, probably as result of root decay. Soybean responded to phosphates applied on the soil surface or in the seed furrow; however, application of soluble P in the seed furrow should not be discarded. In tropical soils with a history of P fertilization, soluble P sources may be substituted for natural reactive phosphates broadcast on the surface. The planting operation may be facilitated through reduction in the rate of P applied in the planting furrow in relation to the rates currently applied.
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TABATABAI, M. A. "Soil Organic Phosphorus." Soil Science 147, no. 1 (January 1989): 77. http://dx.doi.org/10.1097/00010694-198901000-00013.
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Kashem, Md Abul, Olalekan Oluwole Akinremi, and Geza Joseph Racz. "Phosphorus fractions in soil amended with organic and inorganic phosphorus sources." Canadian Journal of Soil Science 84, no. 1 (February 1, 2004): 83–90. http://dx.doi.org/10.4141/s03-018.
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Information on the P fractions in soils treated with different organic amendments is needed to better manage land application of organic amendments to agricultural soils. This study investigated the forms and distribution of P after 1, 4 and 16 wk in a Lakeland silty clay loam soil using a sequential fractionation procedure. Phosphorus was added at rates of 0, 123, 307 and 614 mg P kg-1 in the form of biosolids, hog manure, cattle manure and fertilizer P. The largest difference among the amendments was in the water-extractable P fraction, which was significantly lower in soil amended with biosolids. Regression analysis showed that the slope of P increment in the H2O fraction as a function of P application rate was four times lower for biosolids (0.06) than for hog manure (0.24) and seven times lower than for fertilizer (0.42) amended soils. In the biosolids-amended soil, there was a net increase of H2O-P, NaOH-Pi and HCl-P fractions at the expense of organic P (NaOH-Po) and residual P fractions after 16 wk of incubation, signifying net P mineralization. In hog manure amended soil, H2O-P decreased by 128 mg kg-1 with a corresponding increase in the NaHCO3-P, possibly due to P sorption during the 16 wk of incubation. The results for cattle manure indicated net immobilization of P as the H2O-P and NaHCO3-P declined while the inorganic P (NaOHPi), HCl-P and residual P increased with incubation time. The transformation of P in fertilizer-amended soil was similar to that of hog manure amended soil. The amount of labile P (defined as H2O-P plus NaHCO3-P) in amended soils followed the order of fertilizer P > hog manure > cattle manure > biosolids. Key words: Phosphorus fractions, sequential P extraction, incubation, organic amendments
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Rogeri, Douglas Antonio, Leandro Bortolon, Clesio Gianello, and Magno Batista Amorim. "Remaining phosphorus content to determine phosphorus availability of the soils in Rio Grande do Sul." Pesquisa Agropecuária Brasileira 52, no. 12 (December 2017): 1203–14. http://dx.doi.org/10.1590/s0100-204x2017001200009.
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Abstract: The objective of this work was to evaluate remaining P compared with soil clay content as a P buffer index to classify P extracted by the Mehlich-1 (M1) and Mehlich-3 (M3) methods in soils from the state of Rio Grande do Sul, Brazil. The experiment was carried out in a completely randomized design with five P2O5 rates (0, 50, 100, 200, and 400 mg kg-1) and two sucessive corn crops, and three replicates, in 20 representative soils of the state. P extracted by M1 and M3 before crop planting was adjusted to P contents in biomass, considering soil buffer capacity. The division of soils into different buffering classes, based on soil clay or remaining P, improved the capacity of estimating soil available P of both methods. However, there was no difference among the correlation coefficients obtained by classifying soils according to the evaluated indexes (remaining P or soil clay) for both M1 and M3 methods. Remaining P is a viable alternative to replace soil clay content to classify soil P extracted with the M1 and M3 methods.
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Groppo, J. D., S. R. M. Lins, P. B. Camargo, E. D. Assad, H. S. Pinto, S. C. Martins, P. R. Salgado, et al. "Changes in soil carbon, nitrogen and phosphorus due to land-use changes in Brazil." Biogeosciences Discussions 12, no. 3 (February 4, 2015): 2533–71. http://dx.doi.org/10.5194/bgd-12-2533-2015.
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Abstract. In this paper soil carbon, nitrogen and phosphorus concentrations and related elemental ratios, as well as and nitrogen and phosphorus stocks were investigated in 17 paired sites and in a regional survey encompassing more than 100 pasture soils in the Cerrado, Atlantic Forest, and Pampa, the three important biomes of Brazil. In the paired sites, elemental soil concentrations and stocks were determined in native vegetation, pastures and crop-livestock systems (CPS). Overall, there were significant differences in soil element concentrations and ratios between different land uses, especially in the surface soil layers. Carbon and nitrogen contents were lower, while phosphorus contents were higher in the pasture and CPS soils than in forest soils. Additionally, soil stoichiometry has changed with changes in land use. The soil C : N ratio was lower in the forest than in the pasture and CPS soils; and the carbon and nitrogen to available phosphorus ratio (PME) decreased from the forest to the pasture to the CPS soils. The average native vegetation soil nitrogen stocks at 0–10, 0–30 and 0–60 cm soil depth layers were equal to approximately 2.3, 5.2, 7.3 Mg ha−1, respectively. In the paired sites, nitrogen loss in the CPS systems and pasture soils were similar and equal to 0.6, 1.3 and 1.5 Mg ha−1 at 0–10, 0–30 and 0–60 cm soil depths, respectively. In the regional pasture soil survey, nitrogen soil stocks at 0–10 and 0–30 soil layers were equal to 1.6 and 3.9 Mg ha−1, respectively, and lower than the stocks found in the native vegetation of paired sites. On the other hand, the soil phosphorus stocks were higher in the CPS and pasture of the paired sites than in the soil of the original vegetation. The original vegetation soil phosphorus stocks were equal to 11, 22, and 43 kg ha−1 in the three soil depths, respectively. The soil phosphorus stocks increased in the CPS systems to 30, 50, and 63 kg ha−1, respectively, and in the pasture pair sites to 22, 47, and 68 kg ha−1, respectively. In the regional pasture survey, the soil phosphorus stocks were lower than in the native vegetation, and equal to 9 and 15 kg ha−1 at 0–10 and 0–30 depth layer. The findings of this paper illustrate that land-use changes that are currently common in Brazil alter soil concentrations, stocks and elemental ratios of carbon, nitrogen and phosphorus. These changes could have an impact on the subsequent vegetation, decreasing soil carbon, increasing nitrogen limitation, but alleviating soil phosphorus deficiency.
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Yang, Mei, and Huimin Yang. "Utilization of soil residual phosphorus and internal reuse of phosphorus by crops." PeerJ 9 (July 15, 2021): e11704. http://dx.doi.org/10.7717/peerj.11704.
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Phosphorus (P) participates in various assimilatory and metabolic processes in plants. Agricultural systems are facing P deficiency in many areas worldwide, while global P demand is increasing. Pioneering efforts have made us better understand the more complete use of residual P in soils and the link connecting plant P resorption to soil P deficiency, which will help to address the challenging issue of P deficiency. We summarized the state of soil “residual P” and the mechanisms of utilizing this P pool, the possible effects of planting and tillage patterns, various fertilization management practices and phosphate-solubilizing microorganisms on the release of soil residual P and the link connecting leaf P resorption to soil P deficiency and the regulatory mechanisms of leaf P resorption. The utilization of soil residual P represents a great challenge and a good chance to manage P well in agricultural systems. In production practices, the combination of “optimal fertilization and agronomic measures” can be adopted to utilize residual P in soils. Some agricultural practices, such as reduced or no tillage, crop rotation, stubble retention and utilization of biofertilizers-phosphate-solubilizing microorganisms should greatly improve the conversion of various P forms in the soil due to changes in the balance of individual nutrients in the soil or due to improvements in the phosphatase profile and activity in the soil. Leaf P resorption makes the plant less dependent on soil P availability, which can promote the use efficiency of plant P and enhance the adaptability to P-deficient environments. This idea provides new options for helping to ameliorate the global P dilemma.
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Groppo, J. D., S. R. M. Lins, P. B. Camargo, E. D. Assad, H. S. Pinto, S. C. Martins, P. R. Salgado, et al. "Changes in soil carbon, nitrogen, and phosphorus due to land-use changes in Brazil." Biogeosciences 12, no. 15 (August 7, 2015): 4765–80. http://dx.doi.org/10.5194/bg-12-4765-2015.
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Abstract. In this paper, soil carbon, nitrogen and phosphorus concentrations and stocks were investigated in agricultural and natural areas in 17 plot-level paired sites and in a regional survey encompassing more than 100 pasture soils In the paired sites, elemental soil concentrations and stocks were determined in native vegetation (forests and savannas), pastures and crop–livestock systems (CPSs). Nutrient stocks were calculated for the soil depth intervals 0–10, 0–30, and 0–60 cm for the paired sites and 0–10, and 0–30 cm for the pasture regional survey by sum stocks obtained in each sampling intervals (0–5, 5–10, 10–20, 20–30, 30–40, 40–60 cm). Overall, there were significant differences in soil element concentrations and ratios between different land uses, especially in the surface soil layers. Carbon and nitrogen contents were lower, while phosphorus contents were higher in the pasture and CPS soils than in native vegetation soils. Additionally, soil stoichiometry has changed with changes in land use. The soil C : N ratio was lower in the native vegetation than in the pasture and CPS soils, and the carbon and nitrogen to available phosphorus ratio (PME) decreased from the native vegetation to the pasture to the CPS soils. In the plot-level paired sites, the soil nitrogen stocks were lower in all depth intervals in pasture and in the CPS soils when compared with the native vegetation soils. On the other hand, the soil phosphorus stocks were higher in all depth intervals in agricultural soils when compared with the native vegetation soils. For the regional pasture survey, soil nitrogen and phosphorus stocks were lower in all soil intervals in pasture soils than in native vegetation soils. The nitrogen loss with cultivation observed here is in line with other studies and it seems to be a combination of decreasing organic matter inputs, in cases where crops replaced native forests, with an increase in soil organic matter decomposition that leads to a decrease in the long run. The main cause of the increase in soil phosphorus stocks in the CPS and pastures of the plot-level paired site seems to be linked to phosphorus fertilization by mineral and organics fertilizers. The findings of this paper illustrate that land-use changes that are currently common in Brazil alter soil concentrations, stocks and elemental ratios of carbon, nitrogen and phosphorus. These changes could have an impact on the subsequent vegetation, decreasing soil carbon and increasing nitrogen limitation but alleviating soil phosphorus deficiency.
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Matula, J. "Differences in available phosphorus evaluated by soil tests in relation to detection by colorimetric and ICP-AES techniques." Plant, Soil and Environment 56, No. 6 (June 3, 2010): 297–304. http://dx.doi.org/10.17221/23/2010-pse.
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Differences in the evaluation of soil phosphorus status by three soil tests (Mehlich 3, extraction with NH<sub>4</sub>-acetate and water extraction) were tested on 63 agricultural soils with different agrochemical characteristics from the territory of the Czech Republic. Differences between the colorimetric determination of phosphorus and ICP technique were studied. The median of the values of phosphorus supply in soils determined by soil tests was considerably different. Compared to the colorimetric detection of water extraction of soils the median of the NH<sub>4</sub>-acetate test showed 2.2 times higher values and in Mehlich 3 test the values were 34.8 times higher. The largest difference between the end-point analytical techniques of phosphorus determination, colorimetry and ICP-AES, was observed in the soil test of water extraction. The median of the values determined by ICP-AES was higher by 47%. In NH<sub>4</sub>-acetate extraction of soils the median of the measured values of phosphorus was higher by 12% and in Mehlich 3 extraction by 7%. Differences in phosphorus concentrations determined by colorimetry and by ICP-AES increased as the phosphorus supply in soils decreased. When the supply of 'available' phosphorus in soil is given, it is always necessary to specify the used soil test including the end-point analytical technique of phosphorus determination to avoid the misleading interpretation of results. The problem of phosphorus in agriculture and in the environment requires thorough revision and methodical standardization.
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Weaver, DM, GSP Ritchie, and RJ Gilkes. "Phosphorus sorption by gravels in lateritic soils." Soil Research 30, no. 3 (1992): 319. http://dx.doi.org/10.1071/sr9920319.
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The effect of sesquioxidic gravels (>2 mm size fraction) on phosphorus sorption by two gravelly lateritic soils was investigated by phosphorus sorption experiments, X-ray diffraction, autoradiography and electron microscopy.In one soil the abundance and size of gravels decreased downslope. As the gravel content of both soils increased (13-61%), the proportion of large (>8 mm) gravels increased (0-70%). Phosphorus sorption increased in the order: (>2 mm fraction) < (whole soils) < (<2 mm fraction). Phosphorus sorption on lateritic gravels (>2 mm) decreased with increasing gravel size and increased with increasing time. Phosphorus sorption by whole soils decreased with increasing gravel content. Phosphorus sorption by the >2 mm fraction was principally by the external surfaces of the gravels. The estimation of phosphorus application rates for lateritic soils depended on the amount of phosphorus required by the plant and the gravel content of the soil. The former is the important factor at low soil gravel contents whereas the latter becomes more important as the gravel content increases. The implications for fertilizer management on the soil with consistent relationships between landscape position, gravel content and subsequent P sorption properties of whole soils are discussed.
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KUPATADZE, Ketevan. "INVESTIGATION OF PHOSPHATE-ION RETENTION STRENGHT IN SOME TYPES OF KAKHETI SOILS." SOUTHERN BRAZILIAN JOURNAL OF CHEMISTRY 27, no. 27 (December 20, 2019): 1–7. http://dx.doi.org/10.48141/sbjchem.v27.n27.2019.7_2019.pdf.
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The presented article describes the soil types existing in east Georgia, particularly in several villages of Gurjaani Municipality-Vazisubani, Kalauri, Mukuzani, Shashiani. Meadow-brown and brown soils represent good soil types for viticulture development in Kakheti. The vineyards cultivated on these soils produce such wellknown wines as Tsinandali, Vazisubani, Mukuzani, Akhasheni, Gurjaani, Manavi. The study explores brown carbonate and meadow-brown soil lab tests to examine the absorption of phosphate ions by them. The study showed that the amount of phosphorus deposited through soils is sufficiently absorbed under various conditions, having a positive effect on the amount of crop. Was compared the rates of phosphate absorption in these soils with the efficiency of phosphorus fertilizers, which showed that the higher the absorption of phosphorus, the lower the amount of phosphorus available to the plant and the lower the yield, and the lower the strength of phosphorus retention, the higher the amount of phosphorus to be consumed by the plant and the higher the yield. But under the conditions of high cultivation degree, the strength of phosphorus absorption became weak, resulted in a large amount of exchangeable and movable phosphates already existing in the soil, which is available to the plant. So, the efficacy of phosphorus fertilizers on such soil is weak. The speed of phosphorus absorption in the soil of Gurjaani municipality villages is satisfactory. However, in case of a high degree of cultivation (or in case of excess fertilization), the degree of phosphorus retention decreases. Accordingly, phosphorus-containing fertilizers should be used within strictly controlled limits.
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Kupatadze, Ketevan. "Investigation of phosphate-ion retention strenght in some types of Kakheti soils." Southern Brazilian Journal of Chemistry, Volume 27, No. 27, 2019 27, no. 27 (April 22, 2019): 1–7. http://dx.doi.org/10.37633/sbjc.27(27)2019.1-7.
Full textAbstract:
The presented article describes the soil types existing in east Georgia, particularly in several villages of Gurjaani Municipality-Vazisubani, Kalauri, Mukuzani, Shashiani. Meadow-brown and brown soils represent good soil types for viticulture development in Kakheti. The vineyards cultivated on these soils produce such wellknown wines as Tsinandali, Vazisubani, Mukuzani, Akhasheni, Gurjaani, Manavi. The study explores brown carbonate and meadow-brown soil lab tests to examine the absorption of phosphate ions by them. The study showed that the amount of phosphorus deposited through soils is sufficiently absorbed under various conditions, having a positive effect on the amount of crop. Was compared the rates of phosphate absorption in these soils with the efficiency of phosphorus fertilizers, which showed that the higher the absorption of phosphorus, the lower the amount of phosphorus available to the plant and the lower the yield, and the lower the strength of phosphorus retention, the higher the amount of phosphorus to be consumed by the plant and the higher the yield. But under the conditions of high cultivation degree, the strength of phosphorus absorption became weak, resulted in a large amount of exchangeable and movable phosphates already existing in the soil, which is available to the plant. So, the efficacy of phosphorus fertilizers on such soil is weak. The speed of phosphorus absorption in the soil of Gurjaani municipality villages is satisfactory. However, in case of a high degree of cultivation (or in case of excess fertilization), the degree of phosphorus retention decreases. Accordingly, phosphorus-containing fertilizers should be used within strictly controlled limits.
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Hernandez, Jorge David, and Randy Killorn. "Phosphorus fertilizer by-product effect on the interaction of zinc and phosphorus in corn and soybean." Canadian Journal of Soil Science 89, no. 2 (May 1, 2009): 189–96. http://dx.doi.org/10.4141/cjss07069.
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The application of high phosphorus fertilizer by-products to farmland is a common practice used to reduce storage volume and disposal cost. However, because Iowa soils are generally high in both phosphorus and zinc, there are environmental and fertility questions concerning their application to farmland. A greenhouse study was conducted to determine the effect of a soil-applied fertilizer by-product on the zinc-phosphorus relationship in corn and soybean plants grown on three Iowa soil series: Belinda, Downs, and Haig. The soils were mixed with a high-phosphorus fertilizer by-product and plants were also collected and analyzed for phosphorus and zinc content and uptake. Soil samples were analyzed for phosphorus and zinc content. The experiment was repeated, switching pots to assess the residual effect after one cycle of rotation. The treatments were arranged in a totally randomized design with three replications. The results indicated that the high phosphorus fertilizer by-product increased soil and plant concentrations of phosphorus in soybean and corn plants and soils. However, the increase of P concentration did not induce changes in the phosphorus-zinc interaction in corn and soybean plants in any of the studied soils. Key words: Phosphorus, corn, soybean, zinc, sludge, by-products, Zn-P relationship, zinc-phosphorus interaction
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Ige, D. V., O. O. Akinremi, and D. N. Flaten. "Evaluation of phosphorus retention equations for Manitoba soils." Canadian Journal of Soil Science 88, no. 3 (May 2, 2008): 327–35. http://dx.doi.org/10.4141/cjss07075.
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One of the key factors in phosphorus management is the P retention capacity (PRC) of the soil. In our previous study, we formulated several equations for estimating the phosphorus retention capacity of Manitoba soils. The objectives of the current study were to evaluate these equations using independent soil samples and to evaluate the influence of manure application on the predictive ability of these equations. Forty representative surface soil samples (20 soils with history of manure application and 20 without manure application history) were collected from across Manitoba. The P retention index (P150) and Langmuir adsorption maximum (Smax) were determined in the laboratory. The measured P retention capacities were then compared with those estimated using the formulated equations. Surprisingly, P150, which was obtained from a single measurement, was more robust than Smax that was obtained from at least 17 measurements as the equations provided a better estimate of P150 than Smax. Equations that were based on soil particle sizes (either percent clay or percent sand) provided poor estimates of soil PRC for the whole soil collection. However, when the soils were grouped on a pH basis, soil particle size worked better for soils with pH <7 than for soils with pH ≥7. The equations also worked better for soils with pH similar to those of the soils that were used to formulate the P retention equations. The accuracy of the predicted P sorption capacity improved with the manured soils due to the direct influence of manure application on soil properties that influence P retention such as Ca and Mg. Overall, the combination of CaM3, MgM3 and AlOx provided the best estimate of the PRC of Manitoba soils. Key words: Soil phosphorus, calcareous soils, phosphorus sorption, phosphorus retention, phosphorus retention capacity, estimating phosphorus retention capacity
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Olego, Miguel Ángel, Mateo D. Cuesta-Lasso, Fernando Visconti Reluy, Roberto López, Alba López-Losada, and Enrique Garzón-Jimeno. "Laboratory Extractions of Soil Phosphorus Do Not Reflect the Fact That Liming Increases Rye Phosphorus Content and Yield in an Acidic Soil." Plants 11, no. 21 (October 27, 2022): 2871. http://dx.doi.org/10.3390/plants11212871.
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In addition to aluminum and other heavy metal toxicities, acidic soils also feature nutrient deficits that are not easily overcome by merely adding the required amounts of mineral fertilizers. One of the most critically scarce nutrients in acidic soils is phosphorus, which reacts with aluminum and iron to form phosphates that keep soil phosphorus availability significantly low. Liming ameliorates acidic soils by increasing pH and decreasing aluminum contents; however, it also increases the amount of calcium, which can react with phosphorus to form low-solubility phosphates. In the present work, three liming materials, namely, dolomitic limestone, limestone and sugar foam, were applied on a Typic Palexerult cropped with rye. The effects of these materials on soil properties, including soil available phosphorus extracted with the Olsen and Bray-1 methods, rye phosphorus content in stems and stem and spike harvested biomasses were monitored for nine years. According to the Olsen extraction, the amount of soil available phosphorus generally decreased following liming, with limestone presenting the lowest values; however, the amount of soil available phosphorus increased according to the Bray-1 extraction, though only to a significant extent with the sugar foam from the third year onward. Regardless, the phosphorus content in rye and the relative biomass yield in both stems and spikes generally increased as a consequence of liming. Since crop uptake and growth are the ultimate tests of soil nutrient availability, the inconsistent stem phosphorus content results following the Olsen and Bray-1 extraction methods suggest a lowered efficiency of both extractants regarding crops in soils rich in both aluminum and calcium ions. This decrease can lead to important interpretation errors in the specific conditions of these limed acidic soils, so other methods should be applied and/or researched to better mimic the crop roots’ phosphorus extraction ability. Consequently, the effects of the liming of acidic soils on phosphorus availability and crop performance in the short and long term will be better understood.
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CH'NG, HUCK YWIH, OSUMANU HARUNA AHMED, and NIK MUHAMAD AB MAJID. "IMPROVING PHOSPHORUS AVAILABILITY, NUTRIENT UPTAKE AND DRY MATTER PRODUCTION OF ZEA MAYS L. ON A TROPICAL ACID SOIL USING POULTRY MANURE BIOCHAR AND PINEAPPLE LEAVES COMPOST." Experimental Agriculture 52, no. 3 (September 30, 2015): 447–65. http://dx.doi.org/10.1017/s0014479715000204.
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SUMMARYPhosphorus deficiency in tropical acid soils is a problem because soluble inorganic phosphorus is fixed by aluminium and iron. Organic amendments could be used to overcome phosphorus fixation in acid soils. Thus, the objectives of this study were to (i) improve soil phosphorus availability using biochar and compost produced from poultry manure and pineapple leaves respectively, and (ii) determine whether the use of biochar and compost could improve phosphorus, nitrogen, potassium, calcium and magnesium uptake and dry matter production of Zea mays L. cultivation on a tropical acid soil. Organic amendments significantly increased soil pH compared with non-organic amendments. Organic amendments also significantly reduced exchangeable acidity and exchangeable forms of aluminium and iron, and effectively fixed aluminium and iron instead of phosphorus. As a result, phosphorus availability in soil increased. Besides increasing the availability of nitrogen, potassium, calcium and magnesium in soil, organic amendments improved nutrients uptake and dry matter production of Zea mays L. Biochar and compost can be used to improve the productivity of Zea mays L. on acid soils by reducing phosphorus fixation.
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Alakeh, Mofor Nelson, Njoyim Estella Buleng Tamungang, and Fai Joel Alongifor. "Phosphorus Adsorption and Its Correlation with Physicochemical Properties of Volcanic-Influenced Soils of Meupi-Awing in Northwest Cameroon." Applied and Environmental Soil Science 2022 (August 24, 2022): 1–11. http://dx.doi.org/10.1155/2022/6890503.
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This study evaluated the physicochemical properties and phosphorus adsorption characteristics of surface soils (0–30 cm) of Meupi on the flank of Mount Lefo-Awing. In volcanic-influenced soils, usually characterized by high acidity, phosphorus is often not readily available to plants, and this deficit tends to limit plant growth. Soil physicochemical properties and phosphorus adsorption studies were carried out using standard techniques. Results of soil physicochemical studies showed that the soils were strongly acidic (pH ranged from 4.7 to 5.1), with low available phosphorus (5.47 to 6.97 mg/kg). The apparent equilibrium time for phosphorus to be adsorbed in the analyzed soils was 24 hours. Phosphorus sorption studies revealed that the rate of phosphorus adsorption increased with an increase in the concentration of added phosphorus but decreased at a certain level at higher concentrations because the soil had no more capacity to adsorb phosphorus. The degree of fitness (R2) of the phosphorus adsorption data for the different adsorption models was in the order Langmuir < Temkin < Van Huay < Freundlich. This suggested that the Freundlich isotherm model was the best fit to describe P sorption processes in soils. The pseudo-second-order kinetics model, which assumed that the rate of phosphorus sorption was dependent on the number of active sites, gave a good fit to predict and describe the kinetics of phosphorus sorption from the soil solution. The capacity of the soil to adsorb phosphorus significantly correlated positively with amorphous Fe (r = 0.953 and p < 0.05 ), free Fe (r = 0.984, 0.976 and p < 0.05 ), free Al (r = 0.994 and p < 0.01 , r = 0.988 and p < 0.05 ), and clay (r = 0.968 and p < 0.05 ), which were the main parameters considered as predictors of phosphorus adsorption activities in the soils.
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Ageba, Mohamed, Nico Straalen, and Basma Assiuty. "Gene expression of the Springtail, Folsomia candida exposed to excess phosphorous in different soils." EGYPTIAN JOURNAL OF EXPERIMENTAL BIOLOGY (Zoology) 18, no. 1 (2022): 115. http://dx.doi.org/10.5455/egysebz.20220528075821.
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The gene expression measurements can be used as a biomarker for species functioning under stressed conditions in polluted soil. In this study, the response of genes to excessive phosphorous levels in the soil was assessed. The expression of Folsomia candida’s gene encoding the deduced MTC, Cyp6, and HSP70 was evaluated,using quantitative Rt-PCR. F. candida, was exposed to two different field soils at different distances from two fertilizer factories in Kafr El Zayat and Abou Zaabal in Egypt with different levels of phosphorous concentrations. In addition to exposure to phosphate-amended LUFA soil. Our results indicated that the expression of MTC was significantly decreased after exposure to phosphorus-rich field soils and phosphate-amended LUFA soil, Gene expression of Cyp6 was significantly increased in response to higher phosphorous concentrations in soil. The expression of HSP70 did not change in response to all treatments. Gene expression can be used as an early indicator of excess Phosphorous in soil, which effect on the bioavailability of other important nutrients to improve soil quality assessment.
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Björkman, Thomas, and Stephen Reiners. "Meeting Initial Snap Bean Seedling Requirements with Starter Phosphorus or Bicarbonate to Solubilize Soil Phosphorus in High-phosphorus Soils." HortScience 50, no. 4 (April 2015): 590–96. http://dx.doi.org/10.21273/hortsci.50.4.590.
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Starter phosphorus (P) is often recommended for warm-season vegetables sown in cool soil, even if soil P index levels are already high. The cost and environmental risk associated with excessive P fertilization justify re-examination of the practice. The objective of the study was to confirm that performance of early plantings of snap bean (Phaseolus vulgaris L.) is improved by starter P application and to test whether solubilizing soil P with potassium bicarbonate (KHCO3) can serve as an alternative in western New York soils. Addition of starter fertilizer at either recommended (15 kg·ha−1) or supraoptimal (35 kg·ha−1) P rates did not generally improve seedling tissue P concentration, early growth (biomass at flowering), or pod yield. Starter P application increased tissue P in only two of 11 experiments, and it never increased yield. Application of 6 kg·ha−1 KHCO3 to release soil-bound phosphate was not phytotoxic to snap beans. In the two experiments in which starter P increased tissue P, KHCO3 application had a smaller effect in one and no effect in the other. KHCO3 application did not increase yield in any of the six experiments where it was tested. A direct test of the contribution of P limitation to the poorer performance of early plantings showed that neither starter P nor KHCO3 application increased yield at early planting. Seasonal differences in crop performance could not be attributed to mineralization of soil phosphate after soil warmed. Water-extractable soil P was not lower in the spring than in summer, remaining constant at all 11 bean fields that were sampled from mid-April through mid-July. In these trials, P was likely not growth-limiting in the cool soils tested. Because starter P may not be necessary in vegetable soils testing high or very high for P, vegetables would also not likely benefit from bicarbonate application under high P conditions.
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Ho, Goen E., and Suprihanto Notodarmojo. "Phosphorus movement through soils and groundwater: application of a time-dependent sorption model." Water Science and Technology 31, no. 9 (May 1, 1995): 83–90. http://dx.doi.org/10.2166/wst.1995.0347.
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Pollution of groundwater, wetlands, rivers, estuaries and near shore waters by phosphorus is now fairly common due to run-off from agricultural areas and wastewater discharges. In the application of fertilisers in agriculture it has been observed that sandy soils result in high phosphorus concentrations in the run-off. On the other hand loamy soils result in less phosphorus run-off. Phosphate-phosphorus sorption by soils has been observed to be time dependent. A model has been developed to describe the movement of phosphorus through soils to take into account the processes of convection, dispersion and time-dependent sorption. The model enables prediction of phosphorus breakthrough in a soil column. A comparison is made of predicted breakthrough curves with results obtained using two types of soil: a sandy soil from Australia and a loamy soil from Indonesia. The model has direct application to field situations where phosphate-phosphorus moves vertically downward through the unsaturated zone to the water table, and horizontally through the groundwater aquifer. Parameters of the model can potentially be derived from simple batch sorption experiments.
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Kashem, Md Abul, Olalekan Oluwole Akinremi, and Geza Joseph Racz. "Extractable phosphorus in alkaline soils amended with high rates of organic and inorganic phosphorus." Canadian Journal of Soil Science 84, no. 4 (November 1, 2004): 459–67. http://dx.doi.org/10.4141/s03-085.
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Information on the extractable P in soils treated with different organic amendments and how it changes with time is important to a sound management of manure addition to agriculture soils. This laboratory study investigated the impact of adding municipal biosolids, hog and cattle manures and monoammonium phosphate (MAP) on extractable P in soils. Phosphorus was added at rates of 0, 110, 220, 440 and 880 mg P kg-1 for the Osborne soil (Gleysolic Humic Vertisol), and 0, 123, 307 and 614 mg P kg-1 for the Lakeland soil (Gleyed Rego Black Chernozem) in the form of biosolids, hog manure, cattle manure and MAP. The soils were incubated at field capacity for 1, 4, 16 and 32 wk after which they were extracted using H2O, NH4Cl, NaHCO3 (Olsen P), and the Kelowna and Mehlich-3 extracts. Regardless of extractant and soil, extractable P was small 1 wk after adding biosolids (17-93 mg kg-1 as Olsen P) and large with MAP (59-672 mg kg-1 as Olsen P) while hog and cattle manures were intermediate between biosolids and MAP (20-461 mg kg-1 as Olsen P). In biosolids-amended soils, extractable P increased slightly with increasing incubation time indicating net P mineralization. With MAP, extractable P declined from 672 mg kg-1 after 1 wk to 157 mg kg-1 after 16 wk of incubation at the highest P application rate in the Osborne soil. In the Lakeland soil, the decrease in extractable P with MAP addition was small (from 398 to 332 mg kg-1) and was similar to the changes with cattle manure P with incubation time. Extractable P with cattle manure in the Osborne soil and with hog manure in the Lakeland soil did not change with incubation time. In both soils, extraction efficiency was in the order of H2O < NH4Cl < NaHCO3 < Kelowna < Mehlich-3. Across P application rates, the efficiency of added P as measured by NaHCO3 increased only with biosol ids from 12% after 1 wk to 21% after 32 wk of incubation, while it decreased in the same period from 55 to 44% with hog manure, from 34 to 32% with cattle manure and from 74 to 17% with MAP in the Osborne soil. Soil samples taken 4 wk following addition o f hog and cattle manures should reflect plant-available P, while soil samples taken within the same period following the application of biosolids are likely to underestimate plant-available P. Key words: Extractable phosphorus, organic amendments, soils, single extraction, incubation
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Souza, Carlos Henrique Eiterer de, Roberto dos A. Reis Jr, Victor Gustavo Soares Ribeiro, Murilo Mendes Machado, Miguel Martins Neto, and Paulo Henrique Soares. "Enhanced-Efficiency Phosphorous Fertilizer Impacts on Corn and Common Bean Crops and Soil Phosphorus Diffusion." Journal of Agricultural Science 12, no. 7 (June 15, 2020): 15. http://dx.doi.org/10.5539/jas.v12n7p15.
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Phosphorus (P) supply to crops is a major constraint on the quantity and quality of food production in tropical soils, which are often characterized by highly weathered soils having low phosphorus use efficiency. Increasing P fertilizer use efficiency is a good tool for increasing food production to feed an increasing world population. Enhanced efficiency P fertilizer is used to achieve this goal. The lack of information about soil P diffusive flux and corn and common bean yield response with increased efficiency P fertilizers justify studies to evaluate the performance of this type of fertilizer. The aims of this study were to evaluate P diffusive flux and corn and common bean crop response to P sources and rates. A laboratory trial was carried out to evaluate soil P diffusive flux in response to P sources (MAP and Policote coated MAP). Field trials were carried out to evaluate corn and common bean yields in response to P sources (MAP and Policote coated MAP) and rates. Policote, an additive based on water-soluble polymers, is an anionic copolymer with iron an aluminum affinity. Increasing contact time between P-fertilizers and soil reduced phosphorus diffusive flux. Policote coated P-fertilizer resulted in higher phosphorus diffusion than conventional phosphorus fertilizer. Phosphorus fertilization increased corn and common bean yields. Policote coated phosphorus fertilizer resulted in higher agronomic P efficiency use, corn, and common bean yields than conventional phosphorus fertilizer. Policote coated P fertilizer can be used as an enhanced efficiency fertilizer and is a more efficient way to deliver required phosphorous to plants. Reducing farm investment, increasing agricultural profits, preserve phosphatic rocks reserves, and avoid the overuse of phosphate fertilizer could be realized through the rational use of enhanced efficiency fertilizers and fertilizer rate use reduction.
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Dobermann, Achim, Thomas George, and Niels Thevs. "Phosphorus Fertilizer Effects on Soil Phosphorus Pools in Acid Upland Soils." Soil Science Society of America Journal 66, no. 2 (2002): 652. http://dx.doi.org/10.2136/sssaj2002.0652.
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Dobermann, Achim, Thomas George, and Niels Thevs. "Phosphorus Fertilizer Effects on Soil Phosphorus Pools in Acid Upland Soils." Soil Science Society of America Journal 66, no. 2 (March 2002): 652–60. http://dx.doi.org/10.2136/sssaj2002.6520.
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Johnstone, P. R., and T. K. Hartz*. "Soil Phosphorus Status and Environmental Risk." HortScience 39, no. 4 (July 2004): 797B—797. http://dx.doi.org/10.21273/hortsci.39.4.797b.
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Heavy P fertilization in the Salinas Valley of California has increased soil P concentration to levels of environmental concern. To determine the correlation of various soil test procedures with P pollution potential from agricultural land in this region, soil was collected from 30 fields, most in long-term vegetable rotations. Soils were analyzed for bicarbonate-extractable P (Pbc), calcium chloride-extractable P (Pcc), bio-available P (Pba, by an anion-resin membrane technique), and %P saturation (Psat, by an enrichment technique). The soils were then exposed to a simulated irrigation event, and soluble P concentration in runoff determined. In a separate experiment the effect of cover cropping on sediment and soluble P concentration in runoff was investigated; containers of six soils were planted with oats (Horteum vulgare L.), and then compared to containers of fallow soil. Pcc, Pba and Psat were all highly correlated (r = 0.86, 0.89 and 0.90, respectively) with Pbc, which ranged from 15-177 mg·kg-1. Soluble P concentration in runoff was highly correlated with all measures of P status (r = 0.98, 0.93, 0.85 and 0.83 for Pcc, Pba, Psat and Pbc, respectively). These results suggest that while Pbc, the standard agronomic measure of soil P status, is a useful indicator of P pollution potential, Pcc (a simple laboratory procedure that could be adapted as an on-farm `quick test' technique) may be superior for that purpose. Across soils, cover cropping reduced soluble P concentration in run-off by 41%, and sediment in the runoff by 85%.
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Yli-Halla, Markku. "Sulphate sorption by Finnish mineral soils." Agricultural and Food Science 59, no. 1 (January 1, 1987): 41–46. http://dx.doi.org/10.23986/afsci.72245.
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Sulphate sorption by 38 Finnish cultivated mineral soils was determined and its correlation with soil properties was studied. Sulphate sorption was correlated with soil pH (r =—0.46**) and with phosphate sorption (r =0.69***). With increasing soil pH, sulphate sorption decreased in relation to phosphate sorption. Phosphorus status was decisive in explaining the sulphate sorption of the soils. Even if both anions are sorbed by the same soil component (amorphous Al compounds), the sites are not available for sulphate if they are already occupied by phosphate. Sulphate sorption was negligible in soils very rich in easily soluble phosphorus. This was reflected in a close negative correlation between sulphate sorption and acid ammonium acetate (pH 4.65) extractable phosphorus (r =—0.70***). During the last few decades, phosphorus fertilization has increased the amount of easily soluble phosphorus in Finnish fields, which obviously has decreased the capacity of the soils to retain sulphate.
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Füleky, György. "Phosphorus Supply of Typical Hungarian Soils." Agrokémia és Talajtan 55, no. 1 (March 1, 2006): 117–26. http://dx.doi.org/10.1556/agrokem.55.2006.1.13.
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The new hot water percolation (HWP) method was introduced to determine the phosphorus supply of soils from the Soil Bank of 36 Hungarian soils. The present work aimed to explain the availability of phosphorus by determining the inorganic phosphate fractions and using ryegrass test plants. Four inorganic phosphate fractions were distinguished: Fraction I, the sorbed phosphates; Fraction II, the easily soluble Ca phosphates and the Al bound phosphates; Fraction III, the Fe phosphates; and Fraction IV, the hardly soluble Ca phosphates. Fraction II, in which the easily soluble Ca phosphates and Al phosphates accumulate, was the main phosphorus source for the test plants on both calcareous and non-calcareous soils. Fraction III (the iron phosphates) plays a greater role in non-calcareous soils, while Fraction IV (the hardly soluble Ca phosphates) in calcareous soils. Both fractions are closely connected with soil development, and with soil properties such as pH and CaCO 3 content. The hot water percolation method reflects the phosphorus supply of soil as well as that measured with ryegrass plants and with the AL method. This new HWP method is in good correlation with the main source of phosphate, with fraction II. For routine purposes the first collected HWP fraction can possibly be used to determine the phosphorus supply of soil correlating well with the phosphorus uptake of test plants.
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Goundar, M. S., R. J. Morrison, and C. Togamana. "Phosphorus requirements of some selected soil types in the Fiji sugarcane belt." South Pacific Journal of Natural and Applied Sciences 32, no. 1 (2014): 1. http://dx.doi.org/10.1071/sp14001.
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The availability of phosphorus (P) in soil is perceived to be one of the limiting factors to sustainable sugarcane production in Fiji. The main objective of this research was to ascertain the amount of bioavailable phosphorus in some Fiji sugarcane growing area soils; this will be valuable in improving the determination of the required amount of inorganic fertilizer to be applied to the soil. In this study, twelve different soils were selected from the sugarcane belt of Fiji and phosphorus buffer index (PBI) and phosphorus isotherm experiments were performed. Soil physical and chemical parameters were also measured and Pearson’s correlation tests used to identify patterns. It was found that Oxisols had the highest PBI values ranging from 134 to 170 while Inceptisols had the lowest ranging from 33 to 54. The PBI data followed a similar pattern to the generated isotherm curves of the different soil types. Most interest was in identifying soils with low PBIs as they have greater potential for P leaching through runoff into waterways. Clay content showed a strong positive correlation with PBI (R = 0.76, p ≤ 0.005). There is strong association with phosphorus fixation in soil with increasing levels of Al and Fe in the soil. Phosphorus availability and P fixation varied with soil types.
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Zhao, Xiaorong, Guitong Li, and Qimei Lin. "Interference of Soil‐Extractable Phosphorus in Measuring Soil Microbial Biomass Phosphorus." Communications in Soil Science and Plant Analysis 39, no. 9-10 (May 2008): 1367–74. http://dx.doi.org/10.1080/00103620802004060.
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