通过连续5年(2013—2017年)长期的观测试验,研究了水氮交叉耦合(W1N1,W1N2,W1N3,W2N1,W2N2,W2N3,W3N1,W3N2,W3N3)对水稻根区土壤氮素累积及其产量的影响,为集约化农田最大化发挥化肥生态效应和优化氮素管理提供技术参考。结果 表明:(1)水氮耦合对水稻植株的生长均具有明显的促进作用,水氮耦合处理的水稻株高、根长、叶面积指数、茎粗、单株地上和地下生物量均高于W1N1,其中水稻生长各指标以W2N3,W3N1和W3N2较大,W1N1最小。(2)土壤剖面无机氮含量自上而下呈现由高到低的变化,水氮耦合处理间的差异主要体现在10 cm,30 cm无机氮含量趋于一致,说明在本研究中水氮耦合对深层土壤无机氮淋洗发生较少。(3)植株不同部位的氮积累量表现出较大的差异,穗部的氮积累量最高,其次是叶片,根部碳氮积累量最低。(4)氮素吸收率、氮素利用率和氮素偏生产力氮浓度随施氮量增加呈先增加后降低趋势。整体上,土壤剖面无机氮含量自上而下呈现由高到低的变化,不同施氮处理间的差异主要体现在10 cm。水稻土壤无机氮吸收量在W2N2处理下达到最大,水稻土壤无机氮残留量在W2N2处理下达到最小,呈V型变化规律。(5)水氮耦合对水稻生物量积累和氮素吸收利用有明显的影响。水氮耦合显著增加了水稻吸氮量、氮素吸收率、氮素利用率和氮素偏生产力。(6)水氮耦合促进了水稻穗数、穗粒数、穗长、穗粗、千粒重和产量的提高,其中水稻产量及产量构成因素以W2N3,W3N1和W3N2较大。以上结果说明水氮耦合对水稻根区土壤氮素累积及其产量起到一定的促进作用。
The effects of water-nitrogen coupling on soil nitrogen accumulation in rice root area and yield were studied through long-term observation experiments for 5 consecutive years(2013—2017), which can provide theoretical basis and technical reference for maximizing the ecological effect of fertilizer and optimizing nitrogen management in intensive farmland. The results showed that:(1)the coupling of water and nitrogen significantly promoted the growth of rice plants; the plant height, root length, leaf area index, stem diameter and aboveground and belowground biomass of the single plant were all higher than those of W1N1, among which the values of W2N3,W3N1 and W3N2 were the largest, while the value of W1N1 was the smallest;(2)the inorganic nitrogen content in soil profile changed from the high level to low level from top to deep layers, and the difference between water-nitrogen coupling treatments mainly occurred in the 10 cm layer, and inorganic nitrogen content in 30 cm layer tended to be the same, indicating that the water-nitrogen coupling had little effect on the inorganic nitrogen leaching in deep soil in this study;(3)different parts of the plant showed great differences in nitrogen accumulation, with the highest nitrogen accumulation in ear, followed by leaf, and the lowest carbon and nitrogen accumulation in root;(4)nitrogen absorption rate, nitrogen utilization rate, nitrogen partial productivity and nitrogen concentration increased first and then decreased with the increase of nitrogen application amount; on the whole, the inorganic nitrogen content in soil profile changed from high level to low level from top to deep layers, and the difference between different nitrogen application treatments mainly occurred in 10 cm layer; the inorganic nitrogen absorption in rice soil reached to the maximum under W2N2 treatment, and then decreased to a certain extent, presenting an inverted V-shaped pattern; the inorganic nitrogen residue in rice soil reached to the minimum under W2N2 treatment, and then increased to a certain extent, presenting V-shaped pattern;(5)the coupling of water and nitrogen had obvious influence on biomass accumulation and nitrogen absorption and utilization of rice; the coupling of water and nitrogen significantly increased the nitrogen uptake, nitrogen absorption rate, nitrogen utilization rate and partial nitrogen productivity of rice;(6)water-nitrogen coupling promoted the increase of rice panicle number, panicle grain number, panicle length, panicle width, 1000-grain weight and yield under the treatments, among which were the largest under W2N3,W3N1 and W3N2 and were the smallest under W1N1. The above results indicate that the coupling of water and nitrogen can promote the accumulation of soil nitrogen in rice root area and yield.
