地下滴灌条件下氮肥调控对氮运移规律的影响

Regulating Fertilizer Application to Control Nitrogen Migration under Subsurface Drip Irrigation

【目的】研究地下滴条件下氮肥调控对土壤中氮素运移及吸收的影响。【方法】采用大田氮肥调控管理试验方法,试验设置T1N60(施氮1次,施氮量为60 kg/hm2)处理、T1N120(施氮1次,施氮量为120 kg/hm2)处理、T1N180(施氮1次,施氮量为180 kg/hm2)处理、T3N60(施氮3次,施氮量为60 kg/hm2)处理、T3N120(施氮3次,施氮量为120 kg/hm2)处理和T3N180(施氮3次,施氮量为180 kg/hm2)处理。研究了不同施氮量(60、120、180 kg/hm2)和施氮次数(1次、3次)对土壤中铵态氮量、硝态氮量和玉米吸氮量的影响。【结果】(1)在玉米拔节期施氮前后,相同施氮量不同施氮次数0~60 cm土层内铵态氮量和硝态氮量增幅,T1N60处理分别比T3N60处理提高了16.46%和14.75%,T1N120处理分别比T3N120处理提高了23.23%和7.48%,T1N180处理分别比T3N180处理提高了10.62%和10.05%。而抽穗期和灌浆期施氮前后,1次施氮处理土壤中铵态氮和硝态氮量增幅低于3次施氮处理。(2)在玉米生育末期20~40 cm土层土壤硝态氮残留量,基本上都是3次施氮处理高于1次施氮处理,T3N180处理最高。(3)3次施氮处理玉米平均吸氮量比1次处理提高了3.76%,随着施氮量提高可以极显著提高玉米吸氮量,吸氮量较高处理是T3N180处理和T3N120处理,二者之间差异不显著。【结论】分次施氮促进了玉米对氮素的吸收,有利于氮素储存在玉米根系层内,建议追施氮素采用3次施用,施氮量120 kg/hm2。

【Objective】The movement and transformation of nitrogen in soil impacts nitrogen bioavailability, and the purpose of this paper is to investigate the feasibility of regulating fertilizer application to control nitrogen migration in soil.【Method】Field experiments were conducted with three levels of nitrogen application： 60, 120 and180 kg/hm2, with each applied either just once or in three times to a corn field via subsurface irrigation. During the experiments, spatial distribution of NH＋4 and NO-3 in soil, as well as N accumulation in the plants were measured. Overall, we examined six N fertilizer treatments： applying 60 kg/hm2 once（T1 N60）, applying 120 kg/hm2 once（T1 N120）, applying 180 kg/hm2 once（T1 N180）, applying 60 kg/hm2 in three times（T3 N60）, applying 120 kg/hm2 in three times（T3 N120）, and applying 180 kg/hm2 in three times（T3 N180）.【Result】（1）Applying the fertilizer at the jointing stage just once increased nitrate and ammonium content in 0-60 cm compared with applying it in three times. In particular, the ammonium and nitrate under T1 N60 increased by 16.46% and 14.75% compared T3 N60, increased by 23.23% and 7.48% under T1 N120 compared to T1 N120, and increased 10.62% and10.05% under T1 N180 compared to T3 N180. In contrast, applying the fertilizer in three times at the filling stage increased both ammonium and nitrate in 0-60 cm soil compared to applying the same amount of fertilizer just once.（2）In the late growth stage, the amount of residual nitrate in 20-40 cm in all treatments was higher when applying the fertilizer in three times than applying it just once, maximizing in T3 N180.（3）Nitrogen uptake by plant roots increased by 3.7% on average when the fertilizer was applied in three times compared to applying it just once, especially in T3 N180 and T3 N120.【Conclusion】For a given amount of fertilizer, applying it via several top-addressing can enhance root uptake and reduce leaching and emission in comparison with applying it just once. We suggest applying 120 kg/hm2 of fertilizer via three top-addresses.