Nitrogen and Phosphorus Leaching as Affected by Gypsum Amendment and Exchangeable Calcium and Magnesium

The loss of N and P by leaching is an important issue, especially on agricultural fields with subsurface tile drainage. The objective of this study was to evaluate how gypsum amendment and soil exchangeable Ca2+ and Mg2+ could affect the movement of P, NH4–N, and NO3–N in infiltrated water and soil....

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Bibliographic Details
Published in:Soil Science Society of America journal 2012-03, Vol.76 (2), p.575-585
Main Authors: Favaretto, N, Norton, L.D, Johnston, C.T, Bigham, J, Sperrin, M
Format: Article
Language:English
Subjects:
Agronomy. Soil science and plant productions
ammonium nitrogen
best management practices
Biological and medical sciences
calcium
Earth sciences
Earth, ocean, space
Exact sciences and technology
exchangeable calcium
Experiments
Fundamental and applied biological sciences. Psychology
General agronomy. Plant production
gypsum
leaching
Loam soils
magnesium
nitrate nitrogen
nitrogen
Other nutrients. Amendments. Solid and liquid wastes. Sludges and slurries
phosphorus
Ratios
Runoff
silt loam soils
soil amendments
Soil science
Soil-plant relationships. Soil fertility. Fertilization. Amendments
Soils
Surface water
Surficial geology
tile drainage
water flow
Water pollution
Water quality
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Summary:The loss of N and P by leaching is an important issue, especially on agricultural fields with subsurface tile drainage. The objective of this study was to evaluate how gypsum amendment and soil exchangeable Ca2+ and Mg2+ could affect the movement of P, NH4–N, and NO3–N in infiltrated water and soil. A column experiment was performed using a Miami silt loam soil, and the treatments were (i) control, (ii) gypsum applied at the surface, (iii) gypsum mixed into the 2.5-cm depth, and (iv) alteration of five different target exchangeable Ca/Mg ratios. A clear Plexiglas cylinder was filled with a 15-cm layer of soil; N, P, and K were applied in solution at the surface after the soil had been wetted and drained. Deionized water at a flow of 0.5 mL min−1 was applied and eight leachate fractions, totaling about five pore volumes, were collected. Gypsum (5000 kg ha−1) applied at the surface and mixed into the 2.5-cm depth significantly decreased P and increased NH4–N concentration but had no significant effect on NO3–N leaching. Exchangeable Ca/Mg ratio treatments did not affect soluble nutrient losses; however, leaching of particulate P was significantly less in the Ca-treated soil than the Mg-treated soil. The overall practical conclusion of this study is that to control P transport, it is necessary to add gypsum even with a high soil exchangeable Ca/Mg ratio. The application of gypsum to the soil could be recommended as a best management practice to avoid water pollution by P; on the other hand, this could cause environmental problems by increasing the NH4 soil mobility.
ISSN:0361-5995
1435-0661
DOI:10.2136/sssaj2011.0223