太湖稻麦轮作区减施磷肥对土壤供磷和小麦吸收磷的影响

The effect of phosphorus-reduction on soil phosphorus supply and wheat phosphorus uptake in a rice-wheat rotation system in the Taihu Lake Region

为了探究太湖稻麦轮作区土壤供磷能力,寻找适宜的减磷措施,通过田间减施磷肥试验,以稻麦季均施磷(PR+W)为对照,设置稻季施磷麦季不施磷(PR)、麦季施磷稻季不施磷(PW)、稻麦季均不施磷(Pzero)3种处理,于第7年测定土壤速效磷含量、梯度扩散薄膜技术(Diffusive Gradients in Thin films,DGT)提取态磷含量、小麦产量以及小麦磷吸收量,分析太湖稻麦轮作区减施磷肥对土壤供磷和小麦吸收磷的影响。结果表明:与PR+W处理相比,PW处理的土壤速效磷含量、小麦籽粒产量以及植株全磷含量均无显著降低;但PR处理显著(P<0.05)降低了44.8%的土壤速效磷含量、32.8%的小麦籽粒产量以及27.9%的地上部植株吸收磷量。线性回归分析发现,利用DGT技术提取的磷与土壤速效磷有显著的正相关关系(P<0.05,R2=0.42),且两者皆与小麦籽粒产量、地上部植株全磷含量及地下部植株全磷含量呈显著的正相关关系。可见,麦季施磷稻季不施磷的减磷措施能够保证土壤速效磷供应和小麦吸磷量,并维持小麦籽粒产量,但麦季不施磷的减磷措施会显著降低土壤速效磷含量、小麦吸磷量以及小麦籽粒产量,同时DGT提取磷可作为稻麦轮作系统土壤供磷与作物需磷动态关系研究的评价指标。

A field experiment was performed to investigate the effect of P reduction on soil P supply and wheat P uptake in a flee-wheat rotation system in Taihu Lake Region by analyzing the soil Olsen P, DGT-Labile P, grain yield, and P uptake of wheat. Four fertilization regimes, including P fertilization during both the rice- and wheat-growing seasons（PR＋W, current farming practice, and control）; P fertilization only during the rice-growing season （PR）; P fertilization only during the wheat-growing season （PW）; and no P fertilization during either season（Pzero ） were designed. Compared with the PR＋W regime, the PW treatment did not decrease soil Olsen P, wheat grain yield, or erop total P. In contrast, the PR treatment significantly（P〈0.05 ） reduced the soil Olsen P, grain yield of wheat, and the aboveground crop total P by 44.8%, 32.8%, and 27.9%, respectively. Significant positive correlation was observed between the DGT-Labile P and soil Olsen P（P〈0.05, R^2=0.42）, both of which had a significant positive correlation with the grain yield of wheat and crop total P. In the wheat season, a P regime with P fertilization not only ensures adequate soil P supply and wheat P uptake, but also maintained the grain yield of wheat. In contrast, a P regime without P fertilization significantly reduced the soil Olsen P, P uptake, and grain yield of wheat. DGT-Labile P could assess the relationship between soil P supply and wheat P uptake in rice-wheat rotation systems in the Taihu Lake Region.