Denitrification losses from irrigated crops in central Spain

摘要: Abstract Denitrification losses from irrigated sandy soil in Central Spain were studied through laboratory and field experiments. In both cases, the acetylene inhibition technique was applied. laboratory, potential denitrification estimated by varying nitrate carbon availability as well oxygen depletion water content at a constant (25°C) temperature. Potential evaluated within range of 6–12 kg N ha−1 day−1. When extra contents not supplied, observed ranged 2 to 6 kg N ha−1 day−1 depending on content. The effect temperature also with aim calibrating influence day–night cycle denitrification. A simple experiment carried out indicating N2O+N2 emission four times greater case treatment than for fluctuating temperature, but same average Field experiments years two crops different cycles: oats, grown winter spring short irrigation period, maize, an intensively summer crop. Moreover, three N treatments tested: controls levels one fertilized urea. periodically estimated, simultaneously measured. Daily rates (kg N ha−1 day−1) 0 all 1.2 urea-treated plot. Maximum urea (40.7 kg N ha−1) during whole period experiment; 10% applied fertilizer be lost, mainly maize when high temperatures coincide. Finally, prediction model acceptable results. This makes it possible evaluate agronomic practices relation their losses.