太湖流域典型稻麦轮作农田稻季不施磷的农学及环境效应探究

以太湖流域典型稻麦轮作农田为研究对象开展大田试验,通过设置稻麦季均施磷(PR+W,当前农民施肥习惯)、麦季施磷稻季不施磷(PW)、稻季施磷麦季不施磷(PR)以及稻麦季均不施磷(Pzero,对照)四种施磷处理,提出麦季施磷稻季不施磷(PW)的减磷措施。四年八季作物研究结果表明:与传统PR+W处理相比较,PW处理的作物籽粒和秸秆产量均无显著变化,但却提高磷肥利用率3.54%,同时降低土壤速效磷累积量10.5%~36.7%,减少径流总磷浓度12.0%。据此推算,如果一个稻季不施磷肥,太湖流域1.02×106hm~2水稻土四年可节约P_2O_5约24万t,估算该流域每年可直接节约肥料投入成本3.06亿元。这表明采取麦季施磷稻季不施磷的减磷措施不仅能够保持稳产,而且可节约磷肥(磷矿)资源,降低水环境污染风险,具有农学、环境以及经济效益的三赢潜力。

Agronomic and environmental effects of P fertilization reduction in rice-wheat rotation field in Taihu Lake Region of Southeast China

Over-fertilization of phosphorus(P) fertilizers is a common practice in rice-wheat rotation fields in the Taihu Lake Region(TLR). In this study, a four-year field experiment of eight rice-wheat-growing seasons was conducted to explore the feasibility of omitting P application in rice season. Four different P regimes, including P fertilization for wheat season only(PW), P fertilization for rice season only(PR), P fertilization for both rice and wheat seasons(PR+W), and no P fertilization for both seasons(Pzero) as control, were designed. Compared with PR+W treatment, rice and wheat yields over 4 years did not show significant difference in PW treatment; but the concentrations of Olsen-P and total P in PW treatment declined by 10.5%~36.7% and 12.0%, respectively(P < 0.05), and the utilization efficiency of P fertilizer increased by 3.54%(P < 0.05). Based on the current price of superphosphate, 3.06 billion RMB per year could be saved in TLR. Therefore, the regime of omitting P fertilizer for rice season in rice-wheat rotation field has positive effects on agriculture, environment and economy, and is feasible for at least 4 years in TLR.