施用绿肥条件下减施化肥对土壤养分及持水供水能力的影响

以长期定位试验为基础,设置7个紫云英和化肥施用配比试验处理,以探索施用绿肥情况下减施化肥对土壤养分、持水和供水能力的影响。结果表明:在翻压紫云英条件下,即使不施化肥土壤氮也可基本得到满足,应适量施用化学钾肥,必须合理施用磷肥,以保证土壤全量和速效养分得到平衡和持续供给,化肥施用量减少未显著降低水稻产量;土壤持水、供水能力在处理间的趋势表现为:紫云英+40%化肥紫云英+60%化肥紫云英+80%化肥、紫云英+100%化肥单施100%化肥、单施紫云英CK,与CK相比,其它6个处理田间持水量提高了1.6%~15.4%,有效含水量增幅更大,平均提高1.5%~30.5%,说明紫云英化肥配施能显著提高土壤的持水、供水能力,且化肥施用量越少效果越好,而单施化肥或单施紫云英效果有限。因此,紫云英施用量一定时(22 500 kg/hm~2),化肥施用量应减少至40%甚至更低。

Effect of reducing chemical fertilizer when the green manure applied on soil nutrients,water retention and supply capacities

In this long-term experiment,seven treatments were conducted to investigate effects of the green manure combined with chemical fertilizer on soil nutrients,soil water retention and supply capacities.The results showed that when the green manure was applied,chemical N was not required to apply,but chemical K and P should be applied.The rice yields did not change significantly as chemical fertilizer reduced.Water retention and supply capacity among treatments showed the same trend of green manure plus 40% chemical fertilizer > green manure plus 60% chemical fertilizer > green manure plus 80% or 100% chemical fertilizer > chemical fertilizer alone or green manure alone > the control.Compared with the control,the field water content and the available water content in the other six treatments were improved by 1.6%~15.4% and 1.5%~30.5%,respectively,indicating that chemical fertilizer combined with green manure enhanced the water retention and supply capacities and less water was better,while either of them applied alone showed limited effects.Therefore,when green manure (22 500 kg/hm2) was applied,chemical fertilizer application could be reduced by 60% and even more.