水肥管理及生物炭施用对作物产量和磷效率及磷淋失的影响

Effects of water and nutrient management and biochar application on crop yield,phosphorus use efficiency,and phosphorus leaching

为探讨中国北方褐土区典型种植模式--冬小麦-夏玉米体系水分优化、养分优化以及生物炭施用对作物产量、磷效率和磷素淋失的影响,2016-2019年于陕西杨凌土(黄土母质,自然褐土发育)区进行田间渗漏池试验,设计习惯水肥(CP1、CP2, CP1处理渗漏池深为120~150 cm, CP2处理渗漏池深为100 cm)、灌水优化(CP1-W)、养分优化(CP1-F)、水分养分优化(OPT)、习惯水肥+生物炭(CP2+B)以及水分养分优化+生物炭(OPT+B)7个处理,研究作物产量、磷肥偏生产力和磷素淋失的响应。结果表明,CP1-W、CP1-F和OPT处理3年平均冬小麦、夏玉米及作物总产量均与CP1处理无显著差异。CP1-F和OPT处理较CP1处理均显著增加磷肥偏生产力,平均增幅分别为69.3%和56.4%。与CP1处理相比, CP1-W和CP1-F均没有显著影响各形态磷的淋失量,而OPT处理的颗粒磷淋失量显著减少58.4%。施用生物炭对3年平均作物总产量无显著影响,而在CP2+B处理磷肥偏生产力显著提高43.6%;在OPT+B处理磷肥偏生产力无显著变化。CP2+B处理各形态磷素的淋失量均与CP2处理相似, OPT+B处理第1年可溶性有机磷、颗粒磷和总磷淋失量较OPT处理分别显著降低60.0%、57.1%和62.4%,但后两年OPT+B处理总磷淋失量却显著增加。综合3年的结果发现,在不同条件下施用生物炭对各形态磷素淋失均无显著影响。上述结果表明,褐土区在农户水肥的基础上合理降低水肥用量,可以提高磷肥利用率,降低磷素淋失量,保障作物产量;而施用冬小麦秸秆生物炭对作物产量、磷素淋失无显著影响,对磷肥偏生产力的影响结果不一致,有待进一步研究。

Excessive water and chemical fertilizer application is often reported in North China winter wheat-summer maize rotation systems,resulting in economic losses and environmental issues.Therefore,optimizing water and nutrients(e.g.,P)for crop yield is important.A 3-year field lysimeter experiment was performed on Lou soil(loess-derived and developed on natural cinnamon soil)in Yangling,Shaanxi Province,Northwest China,to investigate P use efficiency and P leaching of winter wheat-summer maize rotation systems in cinnamon soil.Seven treatments were used to investigate crop yield,P partial productivity(PFPP),and P leaching:conventional practices(CP1,lysimeter depth=120–150 cm;CP2,lysimeter depth=100 cm),CP1 plus reduced water supply(CP1-W),CP1 plus reduced nutrient supply(CP1-F),CP1 plus reduced water and nutrient supplies(OPT),CP2 plus biochar application(CP2+B),and OPT plus biochar application(OPT+B).The results showed that the mean wheat,maize,and total wheat+maize yields were similar among CP1,CP1-W,CP1-F,and OPT.Compared with CP1,CP1-F and OPT significantly increased PFPP by an average of 69.3%and 56.4%,respectively.CP1-W and CP1-F did not affect P leaching,but annual particulate phosphorus leaching decreased significantly under OPT treatment(by 58.4%).Biochar use did not affect the mean annual crop yield,but CP2+B significantly increased PFPP(by 43.6%)compared with CP2.OPT-B did not affect PFPP compared with OPT.Each year,all forms of leached P were similar between CP2 and CP2+B.In the first treatment year,OPT+B significantly decreased(compared with OPT)the dissolved organic phosphorus,particulate phosphorus,and total phosphorus(TP)leaching losses by 60.0%,57.1%,and 62.4%,respectively,but TP leaching increased significantly in the following 2 years.The 3-year average showed that biochar application did not affect P loss.Therefore,only reducing water and fertilizer applications to cinnamon soil may improve P use efficiency and reduce P leaching while maintaining crop yield.Applying wheat straw biochar did not affect crop yield or P leaching,and the effect on PFPP was inconsistent.Further studies are needed to clarify the effectiveness of biochar application.