Nitrogen Dynamics and Losses in Direct-Drilled Maize Systems
2007
Alvarez, C.R. | Rimski-Korsakov, H. | Prystupa, P. | Lavado, R.S.
The knowledge of nitrogen (N) losses in direct-drilling agrosystems is essential to develop strategies to increase fertilizer efficiency and to minimize environmental damage. The objectives were i) to quantify the magnitude of N volatilization and leaching simultaneously as affected by different urea fertilization rates and ii) to evaluate the capacity of these specific plant-soil systems to act as a buffer to prevent nitrate leaching. Two experiments were conducted during 2001/02 and 2002/03 growing seasons in Alberti, Argentina. The crop was direct-drilled maize and the soil a Typic Argiudoll. Ammonia losses, N uptake by crop at flowering and harvest, grain yield, N in previous crop residues, and soil nitrate content up to 2-m depths were determined. Nitrogen availability, soil nitrate (NO3)-N up to 1 m plus fertilizer N, was linearly and highly associated with crop N uptake at flowering (R2 = 0.93, P < 0.01) and at harvest (R2 = 0.852, P < 0.01). Around 17.5% of fertilizer N was lost by volatilization in 10 days. The obtained values of residual nitrate N up to the 150-cm depth were associated (R2 = 0.960, P < 0.001) with those predicted by the nitrate leaching and economic analysis package (NLEAP) model. Maize in the direct-drilling system was able to cycle N from the previous crop residues, N from soil organic matter, and N from fertilizers with few losses.
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