紫云英配施不同用量化肥对土壤养分、团聚性及水稻产量的影响

Effects of Applying Chinese Milk Vetch with Different Amounts of Chemical Fertilizer on Soil Nutrients,Aggregation and Rice Yield

利用田间定位试验，探讨翻压等量紫云英条件下，减施化肥对土壤养分、团聚性、团聚体有机碳和全氮分布及水稻产量的影响。共设置4个处理，即紫云英还田分别与100％化肥（A1，当地常规化肥施用量）、80％化肥（A2）、60％化肥（A3）和40％化肥（A4）配施。结果表明，尽管土壤有机碳和全氮含量在处理间无差异，但在化肥施用量减少到60％或80％情况下，〉2mrn和0．25．2mm团聚体内有机碳和全氮含量却明显提高，有机碳和全氮规律分别为A3〉A2、A1〉A4和A2〉A1〉A3、A4；0．25～2mm团聚体是土壤中占绝对优势的粒级，它对土壤有机碳和全氮的贡献也最大，化肥施用量的减少有利于其形成和积累，这利于良好土壤结构的形成；速效氮、磷随化肥施用量的降低而减少，水稻产量并未下降，大小为Al、A2〈A4〈A3。总之，施80％和60％化肥效果优于100％化肥，施40％化肥即可达到100％化肥的效果。因此，在施用等量紫云英（22500kghm-2）条件下，化肥施用量可减少到40％。

Based on the located field experiment, this study aimed to investigate the influences of applying Chinese milk vetch （Astragalus sinicus） combined with different amounts of fertilizer on soil nutrients, aggregation, distribution of aggregate organic carbon and total nitrogen, and rice yield. Four fertilizer treatments were established： the same amount of Chinese milk vetch combined with 100% fertilizer （A1）, 80% fertilizer （A2）, 60% fertilizer （A3）, and 40% fertilizer （A4）, respectively. The results indicated that, soil organic C and total N showed no difference, but they were obviously improved in the aggregates 〉 2 mm and 0.25 - 2 mm when fertilizer application rates decreased to 60% or 80%, fi311owing the trend of A3 〉 A2, A1 〉 A4 and A2 〉 A1 〉 A3, A4, respectively. The 0.25 - 2 mm aggregate size was dominant among four aggregate sizes and contained the highest organic C and total N contents. Reduction in fertilizer application resulted in the formation and accumulation of 0.25 - 2 mm aggregates, which improved soil structure. Available N and P contents decreased as fertilizer was reduced, whereas the rice yields were in the trend of A1 and A2 〈 A4 〈 A3. In conclusion, compared to 100% fertilizer, applying 80% and 60% fertilizer could improve soil quality and rice yield, and applying 40% fertilizer could achieve the same effect. Therefore, on applying the same amount of Chinese milk vetch （22500 kg hm-2）, the application rate of fertilizer could be reduced to 40%.