滴灌水氮管理对玉米种植土壤无机氮含量和氧化亚氮排放的影响

【目的】获得玉米种植土壤氧化亚氮(N₂O)减排的滴灌施肥模式，揭示不同滴灌灌水量和施氮比例下土壤无机氮含量对土壤N₂O排放的影响。【方法】在移动防雨棚内开展2季玉米3种滴灌灌水量(W60、W80和W100分别为田间持水量的50%～60%、70%～80%和90%～100%)和2种滴灌施氮比例(等N量为180 kg·hm-2，其中，F55为50%氮肥作基肥土施、50%氮肥作滴灌施肥，F37为30%氮肥作基肥土施、70%氮肥作滴灌施肥)的田间试验，测定生育期内土壤N₂O通量和不同生育时期土壤无机氮含量，计算不同生育时期和全生育期土壤N₂O排放量，分析土壤N₂O通量与土壤无机氮含量之间的关系。【结果】2季玉米土壤的N₂O排放规律相似；相同施氮比例下，W100水分处理下土壤N₂O排放通量在多数玉米生育时期高于W60和W80，表明高水分处理下土壤N₂O排放通量高于中、低水分处理；相同水分处理下，除夏季玉米苗期外，土壤N

Effect of drip irrigation and nitrogen management on inorganic nitrogen content and nitrous oxide emission in maize-planting soil

Objective The objectives of this study were to obtain a rational drip fertigation mode for reducing nitrous oxide (N₂O) emission in maize-planting soil, and reveal the effects of soil inorganic nitrogen content on N₂O emission under different drip irrigation amount and nitrogen fertigation ratios. Method In the mobile rainproof shelter, two-season maize experiments with three drip irrigation amount (W₆₀, W₈₀ and W₁₀₀ were 50%-60%, 70%-80% and 90%-100% of field water holding capacity, respectively) and two nitrogen fertigation proportions (F₅₅: 50% nitrogen fertilizer applied to soil as basal fertilizer, and 50% nitrogen fertilizer as fertigation, F₃₇: 30% nitrogen fertilizer applied to soil as basal fertilizer, and 70% nitrogen fertilizer as fertigation; Both of F₅₅ and F₃₇ had the equal nitrogen rate of 180 kg·hm^-2) were carried out. The soil N₂O flux over the whole growth stage and soil inorganic nitrogen content at different growth stages were measured. Soil N₂O emissions at the different growth stages and over the whole growth stage were calculated and the relationships between soil N₂O flux and soil inorganic nitrogen content were analyzed. Result The N₂O emission fluxes of corn soil in two seasons were similar. Under the same nitrogen application ratio, soil N₂O emission fluxes under W₁₀₀ water treatment were higher than those under W₆₀ and W₈₀ in most maize growth periods, indicating that soil N₂O emission fluxes under high water treatment were higher than those under medium and low water treatment. Under the same water treatment, soil N₂O emission flux ratio of F₅₅ was lower than that of F₃₇ except in summer maize seedling stage. During the whole growth period, the cumulative emission of soil N₂O under W₆₀F₅₅ treatment in spring was lower than that under other treatments, followed by W₈₀F₅₅, while those under W₆₀F₃₇ and W₈₀F₅₅ treatments in summer were lower. In addition, in two seasons, soil N₂O flux was significantly correlated with nitrate nitrogen and nitrite nitrogen contents, with correlation coefficients ranging from 0.433 to 0.579 and 0.396 to 0.532, respectively.Conclusion W₈₀F₅₅ treatment (70%-80% field water holding capacity, 50% nitrogen fertilizer as basal fertilizer and 50% nitrogen fertilizer as fertigation) reduces N₂O emission from maize-planting soil. In addition, soil nitrate nitrogen and nitrite nitrogen contents significantly affect soil N₂O emission.