冬季作物-双季稻轮作种植模式氮、磷、钾养分循环与产量可持续性特征

Nitrogen, phosphorus and potassium cycling and sustainability of rice yield in a winter crop-double cropping rice rotation system

研究分析农业生态系统NPK 养分循环和产量的可持续性,对实现养分资源优化管理和农业可持续发展具有重要意义。基于长期冬季作物-双季稻轮作种植定位试验,分析了2004—2017 年冬闲-双季稻、马铃薯-双季稻、紫云英-双季稻、黑麦草-双季稻、油菜-双季稻等轮作种植模式早、晚稻产量的可持续性与稳定性;采用投入产出法(Input-Output Analysis)分析不同轮作种植模式NPK 养分循环与平衡状况。结果表明: 1)黑麦草-双季稻模式早稻产量变异系数与可持续性指数分别为0.09 和0.81,说明稻田冬种黑麦草有利于促进早稻产量稳定性和可持续性的提高;油菜-双季稻模式晚稻产量变异系数与可持续性指数分别为0.07 和0.82,说明稻田冬种油菜有益于晚稻产量稳定性和可持续性的提高;2)长期冬季作物-双季稻轮作种植未影响水稻产量和糙米NPK 养分含量(P>0.05);3)在稻田轮作种植周年内目前的NPK 投入水平下,黑麦草-双季稻、紫云英-双季稻、油菜-双季稻、马铃薯-双季稻等模式均存在严重的K 亏缺现象, K 亏缺量分别为375.70 kg(K)·hm^-2、279.98kg(K)·hm^-2、363.71 kg(K)·hm^-2、93.74 kg(K)·hm^-2;黑麦草-双季稻、紫云英-双季稻、油菜-双季稻等模式均在冬季作物种植季存在严重的K 亏缺现象, K 亏缺量分别为240.07 kg(K)·hm^-2、89.57 kg(K)·hm^-2、140.08kg(K)·hm^-2,但马铃薯-双季稻模式在马铃薯种植季K 盈余为255.21 kg(K)·hm^-2;同时黑麦草-双季稻模式和紫云英-双季稻模式均存在冬季作物种植季存在N亏缺, N 亏缺量分别为59.47 kg(N)·hm^-2 和89.17 kg(N)·hm^-2;油菜-双季稻模式和马铃薯-双季稻模式在晚稻种植季均存在严重的K 亏缺现象, K 亏缺量分别为45.93kg(K)·hm^-2、124.33 kg(K)·hm^-2。冬季作物-双季稻轮作种植模式的养分循环是冬季作物和外部投入的NPK 肥料共同驱动的养分循环,建议科学管理冬季作物和3 季的NPK 养分投入。

The study of nitrogen (N), phosphorus (P), and potassium (K) nutrient cycling and yield sustainability in agricultural ecosystems is fundamental for achieving optimal nutrient management and sustainable agricultural development. A long-term experiment of a winter crop-double cropping rice rotation system initiated in 2004 on a red paddy soil in Hunan Province, consisting of five treatments, including fallow-double cropping rice (CK), potato-double cropping rice, ryegrass-double cropping rice, milk vetch-double cropping rice, and rape-double cropping rice with three replicates of all the treatments. The sustainability and stability of double cropping rice yields were analyzed, and N, P, and K cycling and balance were calculated based on an Input-Output analysis method. The results indicated: 1) the sustainable yield index (SYI) and yield stability (CV) of early rice in the ryegrass-double cropping rice rotation system were 0.81 and 0.09, respectively. Winter ryegrass in the paddy field promoted the stability and sustainability of early rice yield. The SYI and CV of late rice in the rape-double cropping rice rotation system were 0.82 and 0.07, respectively. Winter rape in the paddy field improved of yield stability and sustainability of late rice. 2) Long-term winter crop-double cropping rice rotation did not significantly affect rice yield and the N, P, and K contents of brown rice (P > 0.05). 3) Under the current input level of N, P, K in the annual rotation of winter crop and double cropping rice, the ryegrass-double cropping rice rotation, milk vetch-double cropping rice rotation, rape-double cropping rice rotation, and potato-double cropping rice rotation systems had serious K deficiency;the K deficit was 375.70, 279.98, 363.71, and 93.74 kg(K)·hm^-2, respectively. Ryegrass-double cropping rice rotation, milk vetch-double cropping rice rotation, and rape-double cropping rice rotation systems had serious K deficiency in the winter crop planting season, the K deficit was 240.07, 89.57, and 140.08 kg(K)·hm^-2, respectively. However, the potato-double cropping rice rotation system had a K surplus of 255.21 kg(K)·hm^-2 in the potato planting season;simultaneously, both the ryegrass-double cropping rice rotation and milk vetch-double cropping rice rotation systems had a N deficit in the winter crop planting season of 59.47 and 89.17 kg(N)·hm^-2, respectively. Both the rape-double cropping rice rotation and potato-double cropping rice rotation systems had serious K deficiency in the late rice planting season of 45.93 and 124.33 kg(K)·hm^-2, respectively. Nutrient cycling of winter crop-double cropping rice rotation systems was a nutrient cycle driven by winter crops and external N, P, and K fertilizers. Based on the results, the winter crops should be scientifically managed, with the input of N, P, and K in the three seasons.