Effects of different nitrogen reduction modes on yield of spring maize and nitrate-N residue in soils of the southern Loess Plateau

Objectives Effects of different nitrogen reduction modes on yield of spring maize and soil NO3--N residue in the southern Loess Plateau were discussed, and scientific fertilization suggestions were put forward to instruct local maize fertilization and protect environment.Methods A field experiment was conducted in the south of the Loess Plateau for three years. Spring maize was planted with half plastic film mulching in one crop per annum. The experiment consisted of 5 N fertilization treatments, no N application (CK), applying urea N 200 kg/hm2 (Con), applying urea N 160 kg/hm2 (Mod Ⅰ), applying N 160 kg/hm2 of urea plus nitrification inhibitor dicyandiamide (DCD)(Mod Ⅱ), and applying slow-release fertilizer urea formaldehyde (SR) N 160 kg/hm2 (Mod Ⅲ). The yield of maize, the fertilizer N use efficiency and the soil NO3- residues were investigated.Results Compared with conventional N treatment, the grain yields and N uptakes of maize had no significant difference under the three N treatments, with the grain yield difference in range of 0.1-0.5 t/hm2. Compared with the Con, the agronomic efficiencies of fertilizer nitrogen and N partial fertilizer productivities were increased by 20.2%-23.2% and 21.9%-23.7%, respectively. The accumulated amounts of nitrate nitrogen in 0-200 cm soil profile were decreased by 90.7, 97.3 and 100.7 kg/hm2, respectively, with the decrease rates of 44.7%, 47.9% and 49.6% in turn. Conclusions Reducing 20% of conventional nitrogen input will not affect spring maize yield and N uptake significantly, but improve agronomic efficiency of fertilizer-nitrogen and N partial fertilizer productivity. Under the same nitrogen application rate, adding nitrification inhibitor or applying slow-release fertilizer do not show priorities over urea on nitrate-N residue reduction.