Leaching of Total Nitrogen from Nitrogen-15-Labeled Poultry Manure and Inorganic Nitrogen Fertilizer
1999
Bergström, Lars F. | Kirchmann, H. (Holger)
Field lysimeters containing an undisturbed sandy soil were used to evaluate leaching of manure-derived N over 3 yr. Manure labeled with ¹⁵N (poultry excreta), which was either fresh or had been decomposed under aerobic or anaerobic conditions, was applied in May during the first year at a rate corresponding to 100 kg total N ha⁻¹. For comparison, labeled ¹⁵NH₄¹⁵NO₃ (100 kg N ha⁻¹) was applied simultaneously to additional lysimeters while others were left unfertilized. During the second and third year, all lysimeters, except the unfertilized ones, received unlabeled NH₄NO₃ at a rate of 100 kg N ha⁻¹. Each year, barley (Hordeum vulgare L.) was seeded prior to fertilization. Based on the difference method, leaching of total N during the first year was not significantly different (P > 0.05) between lysimeters treated with NH₄NO₃, fresh manure, and anaerobic manure, but lower from those with aerobic manure. Regarding leaching of residual manure- and fertilizer-derived N estimated with the ¹⁵N method, there was a significant difference (P < 0.05) between the NH₄NO₃ fertilized and manured lysimeters. As much as 19, 28, and 26% leached in the treatments with fresh, anaerobically, and aerobically decomposed manure, respectively, whereas only about 3% leached in the NH₄NO₃ fertilized lysimeters in the two subsequent years. The crop uptake of labeled N were smaller in the manured lysimetcrs than in the NH₄NO₃ fertilized lysimeters. These results suggest that there is a greater potential for N leaching in the longterm from animal manures than from inorganic N fertilizers.
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