Sustainable nutrient management in sandy soils - Fate and transport of nutrients from animal manure versus inorganic sources

Sustainable agricultural production practices contribute to minimize the potential negative effects on the environment including reduction in non-point source pollution of groundwater, in addition to various other environmentally sustainable goals. Understanding nutrient leaching patterns from different nutrient sources in a sandy soil is important to develop management alternatives to minimize nutrient leaching, improve nutrient uptake efficiency, thus to make the system Sustainable as well as economically attractive. Leaching column experiment was conducted using Quincy fine sand packed to simulate the natural soil profile of 120 cm depth. The treatments included (1) unamended; (2) 100 kg N ha(-1) as urea; (3) 100 kg ha(-1) each of N and P as urea and KH2PO4; and (4) 200 kg N ha(-1) as manure. All columns received uniform bromide (Br-) applications at 112 kg ha(-1), as KBr and leached with 5 pore volumes (PV; 45 L) of water. The Br- was leached entirely in the second PV of leachate, and Br- retention in the soil was negligible. Leaching of NH4-N was considerably lower than that of NO3-N. Leaching Of PO4-P was negligible in the first 3 PV, but increased rapidly during the subsequent leaching. The amount of P leached was much greater from the soil amended with urea plus KH2PO4 than that with the manure. The residual soil N after the completion of leaching of 5 PV of water showed NH4-N concentrations <= 1.5 mg kg(-1) through the entire depth of the soil column, across all treatments.