黄土高原南部不同减氮模式对春玉米产量及土壤硝态氮残留的影响

【目的】研究了不同减量施氮模式对黄土高原南部春玉米产量、土壤硝态氮残留的影响，提出科学施肥模式，旨在指导当地玉米施肥、保护环境安全。【方法】在黄土高原南部沟壑区农田连续进行了3年的田间试验，供试作物为春玉米，一年一熟，采用半覆膜种植方式。试验设不施氮（CK）；传统施肥模式（Con，施尿素N 200 kg/hm2）；减氮模式Ⅰ（Mod Ⅰ，施尿素N 160 kg/hm2）；减氮模式Ⅱ（Mod Ⅱ，施尿素N 160 kg/hm2和加一定量的硝化抑制剂双氰胺）；减氮模式Ⅲ（Mod Ⅲ，施脲甲醛N 160 kg/hm2）5种处理。调查了玉米产量、收获后土壤硝态氮残留和氮素利用率。【结果】三种减量施氮模式较传统施氮模式施氮量减少20%的情况下，玉米产量连续三年无显著变化（P 0.05），相差0.1~0.5 t/hm2。与Con相比，Mod Ⅰ、Mod Ⅱ、Mod Ⅲ处理的氮肥农学效率及偏生产力分别增加了20.2%~23.2%和21.9%~23.7%，0-200 cm土层NO3--N的残留量分别减少了90.7、97.3、100.7 kg/hm2，其降幅依次为44.7%、47.9%、49.6%。【结论】连续三年减少20%的施氮量不影响春玉米产量及吸氮量，可提高氮肥的农学效率和偏生产力，显著减少土壤剖面NO3--N残留量。在同一施氮量下，添加硝化抑制剂或施用缓控释肥对硝态氮残留量减少作用不甚明显。

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.