长江中游双季稻田不同轮作方式对土壤质量的影响

研究长江中游地区不同种植模式和秸秆还田管理下农田土壤养分、有机碳及其酶活性的变化,评估农业管理措施对土壤质量的影响,可为长江中游双季稻区农业资源高效利用及可持续发展提供理论依据。2012—2017年进行不同轮、连作长期定位试验,设置冬季休耕—双季稻,冬种紫云英—、油菜—、大蒜—和轮作(马铃薯、大蒜、油菜和紫云英年际轮作)—双季稻5个处理,在冬季作物秸秆和水稻秸秆双重还田条件下,通过运用多元方差分析、相关性分析和主成分分析等统计方法,结合南方双季稻田土壤的适宜性,筛选出最小数据集(minimum data set,MDS)中土壤质量指标并测定,最后采用模糊数学方法对双季稻区的土壤质量进行定量评价。结果表明,在长江中游双季稻区,经过6年的冬季种植合适作物并秸秆双重还田,相比冬季休闲处理,除冬季种植大蒜处理外,其他冬种处理均能有效提高稻田土壤质量10.73%～12.91%,不同冬种方式下双季稻田的土壤质量高低依次为不同冬种轮作(0.726)冬季种植油菜(0.723)冬季种植紫云英(0.712)冬季休闲(0.643)冬季种植大蒜(0.638)。由此可见,适宜的轮作方式及秸秆双重还田能显著提高双季稻土壤质量,这为南方稻田健康可持续发展提供了理论支撑。

Effect of various crops rotations on soil quality in double cropping rice field in the middle reaches of the Yangtze River

Improved knowledge that may support the efficient utilization and sustainable development of agricultural resources in the middle reaches of the Yangtze River is still needed. Herein, changes on soil nutrients, organic carbon, and enzyme activities under different planting patterns and straw retention were assessed, and the impact of agricultural management measures on soil quality was evaluated in this particular geographical region. The long-term positioning experiment of different rotational and continuous cropping was carried out from 2012 to 2017, and five treatments of rotation patterns including winter fallow-early rice-late rice, winter Chinese milk vetch-early rice-late rice, winter oilseed rape-early rice-late rice, winter garlic-early rice-late rice, and winter rotation (interannual rotation of potato, Chinese milk vetch, oilseed rape, and garlic)-early rice-late rice were set up. Under the condition of winter crop straw and rice straw retention, the soil quality indexes in minimum data set were selected and determined using multiple variance analysis, correlation analysis, and principal component analysis combined with the suitability of the soil in the southern double cropping rice field. Lastly, the fuzzy mathematics method was used to evaluate the soil quality in the double cropping rice area. The data indicated that six years of winter planting suitable crops and straw retention in the double cropping rice area could effectively improve the soil quality of paddy field by 10.73%-12.91% compared with the winter fallow treatment, with exception of the garlic treatment. The soil quality of double cropping rice field under different rotation patterns was in the order of winter rotation (planting different crops in different years during winter) (0.726) > planting oilseed rape in winter (0.723) > planting Chinese milk vetch in winter (0.712) > winter fallow (0.643) > planting garlic in winter (0.638). Therefore, the soil quality of double cropping rice can be significantly improved by suitable rotation with winter crops and double straw returning, which provides a solid foundation for the healthy and sustainable development of paddy fields in southern China.