灌溉定额和施氮量对机采棉田水分运移及硝态氮残留的影响

水资源短缺和土壤环境污染严重是制约农业可持续健康发展的瓶颈,迫使农民开发和采用可持续的农业生产技术。水分运动机理和氮肥残留行为是评价干旱地区农业水肥管理水平的依据,提高水氮利用效率是降低环境污染这一重要科学问题的重要途径。本研究采用裂区试验设计,以灌溉量为主区,设2250(低灌溉量,W1)、3450(传统灌溉量,W2)和4650 m~3 hm–2 (高灌溉量, W3) 3个灌溉量;设0 (空白, N1)、300 (传统施肥量, N2)和600 kg hm–2 (高施氮量, N3) 3个纯氮投入量,在干旱的中国西北内陆棉区开展2年的田间试验,评估灌溉和施氮策略对水氮运移、籽棉产量、水氮生产效率的影响。结果表明,灌溉量及水氮耦合效应是影响籽棉产量及灌溉水生产力的影响因素,其中灌溉量是主效应。2年均值表明,灌溉量为W1时,施肥量由N1增加至N3,生育期0～80 cm平均土壤含水量呈先显著上升后显著下降的趋势, N2和N3处理较N1处理籽棉产量分别提高13.8%和7.6%,水分利用效率分别提高13.6%和6.8%;灌溉量为W2和W3时,施肥量由N1增加至N3,生育期0～80 cm土层平均含水量...

Coupling effects of irrigation and nitrogen levels on yield,water distribution and nitrate nitrogen residue of machine-harvested cotton

The shortage of water resources and the excessive investment of fertilizer are the bottlenecks that restrict the sustainable and healthy development of agriculture and force farmers to develop and adopt sustainable production technologies.The mechanism of water movement and the residual behavior of nitrogen fertilizer are important scientific issues to evaluate the level of agricultural water and fertilizer management in arid areas.Improving the water and nitrogen utilization efficiency was an important way to reduce environmental pollution.An experiment was conducted using a split plot design with the main area for total irrigation of 2250(W1,non-sufficient drip irrigation),3450(W2,conventional drip irrigation),4650 m³ hm^-2(W3,saturated drip irrigation),and the deputy area of nitrogen(pure N) including 0(N1,no fertilizer),300(N2,conventional fertilization),600 kg hm^-2(N3,excess fertilization) in arid area of northwest China cotton region from 2018 to 2019.The effects of irrigation and nitrogen levels on water distribution,nitrate nitrogen residue,seed cotton,irrigation water,and N fertilizer productive efficiency were evaluated.The results revealed that irrigation and coupling effects of irrigation and nitrogen levels were the influencing factors on seed cotton and water utilization efficiency,among which irrigation was the main effect.Two-year average values demonstrated that the irrigation was W1,nitrogen fertilization amount increased from N1 to N3,and the average soil moisture content of 0–80 cm during the whole growth period increased first and then decreased.Compared with N1 fertilization application,seed cotton yield was 13.8% and 7.6% higher and irrigation water productive efficiency were 13.6% and 6.8% higher under N2 and N3 fertilization application,respectively.When the irrigation was W2 and W3,the nitrogen fertilization amount increased from N1 to N3,and there was no significant difference in the average soil moisture content of 0–80 cm during the whole growth period.Compared with N1 fertilization application,seed cotton yield was 11.4% and 11.5% higher and irrigation water productive efficiency were 13.6% and 6.8% higher under N2 and N3 fertilization application,respectively.With the increase of irrigation,the total average value of 0–80 cm during the whole growth period gradually increased.Irrigation was the main effect on soil nitrate nitrogen accumulation in the main distribution area of 0–40 cm roots,and coupling effects of irrigation and nitrogen levels was the main factor leading to nitrate nitrogen leaching.When the irrigation was W1,nitrate nitrogen accumulated in the 0–40 cm with the increase of nitrogen.And when the irrigation was W3,nitrate nitrogen accumulated in the 40–60 cm with the increase of nitrogen.In conclusion,if the irrigation was higher than 3450 m³ hm^-2 and nitrogen was higher than 300 kg hm^-2,the continued increase of water and nitrogen input failed to increase production,which might result in resource waste and potential pollution to the environment.Therefore,we suggest that water and nitrogen optimization strategies can improve resource utilization efficiency,reduce water and fertilizer input,and healthy development of agriculture.