关中土区冬小麦–夏玉米体系磷肥减施增效技术研究

Techniques to reduce P application rate and improve its efficiency in winter wheat-summer maize system on Eum-Orthic Anthrosols in Guanzhong area

【目的】比较磷肥减施结合调控措施的效果,为合理施用磷肥,提高磷肥利用率,实现区域粮食作物高产高效和绿色发展提供支撑。【方法】冬小麦–夏玉米体系田间试验在陕西关中地区土上进行了3年。共设5个处理:不施磷肥(CK),推荐施磷量撒施(RP),减施15%推荐施磷量条施(85%RP),以秸秆包裹磷肥条施(St85%RP),85%RP结合硫酸铵替代尿素(Am85%RP)。于作物收获期测定小麦和玉米产量、磷肥效率、土壤磷库和作物菌根侵染率。【结果】与CK相比,除85%RP处理小麦籽粒产量没有显著提高,其他施磷处理可显著提高玉米籽粒总产量(增幅17.1%~32.6%)、小麦籽粒总产量(增幅8.9%~12.8%)以及玉米小麦总产量(增幅13.1%~22.5%)。除85%RP处理2018年玉米籽粒和2020年小麦籽粒产量显著低于RP处理外,其余减磷处理均与RP处理没有显著差异。与RP处理相比,85%RP、St85%RP和Am85%RP处理均显著提高了磷素回收率、表观利用率和偏生产力;与85%RP处理相比,St85%RP处理显著提高了磷肥利用率,而Am85%RP处理则提高不显著。与CK相比,所有施磷处理均显著提高了土壤有效磷和微生物量磷含量。与RP处理相比,85%RP处理的土壤有效磷和微生物量磷显著下降,但St85%RP与Am85%RP处理的土壤有效磷无显著差异,St85%RP处理的土壤微生物量磷和水溶态磷含量甚至有显著提高。RP处理的土壤磷表观平衡略有盈余且最接近于平衡,而所有减施15%磷肥处理均表现为亏缺。与RP处理相比,减磷结合调控措施显著提高了小麦根系的菌根侵染率。【结论】当前陕西关中冬小麦–夏玉米作物体系中,在推荐施磷量下减少15%的磷肥投入会造成土壤磷表观亏缺和减产的风险。采用以秸秆包裹磷肥或者用硫酸铵替代尿素的方法,可提高土壤有效磷、微生物量磷含量,提高小麦根系菌根侵染率,进而提高小麦对磷的吸收利用,在提高磷肥利用率的同时避免减磷带来的减产风险,甚至提高作物产量和磷肥效率,是两种高效的磷肥减施增效调控技术。

【Objectives】We studied the possibility of decreasing phosphorus(P) fertilizer application rate and improving its efficiency.【Methods】The treatments included no P application(CK),recommended P application rate(RP),15% off RP(85%RP),straw-wrapped P fertilizer application at 85%RP(St85%RP),and85%RP plus substituting urea with ammonium sulfate(Am85%RP).P fertilizer was broadcast in the RP treatment,and band application was adopted for the other treatments.The crop yield,P fertilizer efficiency,soil P pool,and crop mycorrhizal infection rate were investigated.【Results】Compared with CK,all the other treatments except85%RP significantly increased maize(17.1%-32.6%) and wheat(8.9%-12.8%) grain yields(P<0.05),and the total yield of maize and wheat(13.1%-22.5%).Compared with RP,P reduction treatments occasionally decreased crop yields,e.g.the maize yield in 2018 and the wheat yield in 2020 under 85%RP.85%RP,St85%RP,and Am85%RP had(P<0.05) higher P recovery rate,apparent use efficiency,and partial factor productivity than RP.Further,St85%RP recorded significantly higher P efficiencies than 85%RP.Compared with CK,P application(P<0.05) increased the soil available phosphorus(AP) and the microbial biomass phosphorus(MBP) contents.The soil AP and MBP under 85%RP were(P<0.05) lower than RP.St85%RP and Am85%RP did not decrease the soil AP.St85%RP(P<0.05) increased the MBP and the water-soluble phosphorus(WSP) contents.The apparent soil P balance under RP was slightly surplus and was closer to being balanced,while P reduction treatments recorded deficits.Compared with RP,St85%RP and Am85%RP improved the mycorrhizal infection rate of wheat roots.【Conclusions】In the winter wheat-summer maize cropping system in Guanzhong,a reduction of 15%phosphate input under the recommended P application rate causes a deficit in the apparent soil phosphorus balance,increasing the risk of yield reduction.Reducing 15% of P fertilizer with straw-wrapped P fertilizer or replacing urea with ammonium sulfate could improve available soil P,microbial biomass P,and the mycorrhizal infection rates of wheat roots,thus improving P absorption and utilization in wheat.In addition to improving P fertilizer utilization efficiency,yield reduction risk caused by P reduction was minimized,which improved crop yield.This indicates that the two treatments are highly efficient regulation techniques for improving P fertilizer efficiency.