Overwinter Redistribution and Leaching of Fall-applied Nitrogen

Bauder, J. W.; Montgomery, B. R.

Overwinter Redistribution and Leaching of Fall-applied Nitrogen

1979

Bauder, J. W. | Montgomery, B. R.

Field studies were conducted on irrigated Maddock fine sandy loam (Udorthentic Haploboroll) to determine mineralization and nitrate leaching following fall application of N from Ca(NO₃)₂, (NH₄)₂SO₄, and CO(NH₂)₂. Chloride was used to trace water and NO₃⁻ movement. Amount and distribution of NO₃⁻-N present the following spring was considered an index of N mineralization and redistribution. Mass balance was used to determine loss during the overwinter period. Predominant depth of leaching was 80 to 115 cm each year, although estimated effective precipitation was only 10 to 20% of the soil moisture storage capacity. Some solute was leached to 180 cm. Considerable NO₃⁻ leaching and redistribution was observed following fall application of Ca(NO₃)₂. Nitrate accumulation following (NH₄)₂SO₄ and CO(NH₂)₂ application was restricted to the 0- to 30 cm depth. From October to April net NO₃⁻ accumulation attributed to nitrification and mineralization averaged 58.4 kg/ha per year. Cloride leaching was not affected by N source. On the basis of these results, NO₃⁻-based N sources should not be applied in the fall on these well drained sandy soils since significant N leaching may result.

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