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

Abstract

<p id="C3">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 m ³ 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 m ³ 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.