Effect Of Tillage Practices And Straw Return On Water And Fertilizer Use And Yield Quality Of Mulched Maize

The Loess Plateau is an important area of dry farming in China.Spring maize is one of the main food crops in this region,and its productivity is closely related to food security.To improve food production capacity,a series of plastic film mulching techniques have been developed and improved in dry farming areas,which significantly increased crop yield.However,plastic film mulching decreased soil organic matter content,and produced straw was discarded or burned,resulting in waste of straw resources and environmental pollution.In addition,the nitrogen use efficiency of crops is low,and the nitrogen contained in crop straw cannot be effectively utilized.The present three experiments were set up on the Weibei arid highland of the Loess Plateau with spring maize as the planted crop: different tillage practices under ridge-furrow plastic film mulching(RFPM)(CK,MR,and MP);different straw returning methods under RFPM(CK,SR,and SB);and combination of film mulching and straw returning(CK,WP,and WP-S).The effects of tillage,straw returning and continuous straw returning on spring maize yield and water and fertilizer utilization were studied.The main results are as follows:Different tillage practices under ridge-furrow plastic film mulching(1)In different growth stages,the soil water content of each treatment was MP >MR > CK.The water use efficiency of treatment woth RFPM was significantly higher than that of CK,and the water use efficiency of MP was significantly higher than that of MR.(2)Taking rotary tillage or plow tillage before RFPM led to significant changes in soil nutrient content in ridges and furrows;plow tillage made the fertilizer distributed in the deep soil so that the maize root can absorb the fertilizer nitrogen at the late growth stage better than other treatments.While rotary tillage made the fertilizer concentrated in the ridges so that maize was difficult ot access the fertilizer and the fertilizer utilization rate was lower.The nitrogen use efficiency of different treatments is MP>MR>CK.(3)The maize yield of treatments with RFPM were significantly higher than that of CK,and the yield under MP was 23.42–31.47 % higher than that of MR.The maize grain nitrogen content showed a trend of MP>MR>CK,and taking RFPM significantly increased the maize grain nitrogen content.Compared with MR,MP significantly increased the grain nitrogen content.Different straw returning methods(1)Straw returning enhanced total nitrogen,nitrate nitrogen,and organic matter contents of the surface soil,which showed a trend of SB > SR>CK,and the soil nutrient supplement effect was more obvious under SB.(2)Under different nitrogen fertilizer gradient,compared with CK,the yield of SB increased by 6.95 % and16.17 % in 2019,respectively.In 2020,the yield of SB increased by 14.2 % and 14.62 %,respectively.After maize harvest,the pattern of nitrogen accumulation per plant was also SB>SR>CK,and the grain nitrogen content of treatments with straw returning was significantly higher than that of CK.The aboveground nitrogen accumulation and absorption efficiency was significantly different(SB> SR>CK).The treatments with straw returning significantly increased the aboveground nitrogen accumulation,nitrogen absorption efficiency and nitrogen harvest index.Long-term effect of straw returning(1)Compared with CK,soil water holding capacity of WP and WP-S were significantly improved,and WP-S had the highest water use efficiency across the treatments.(2)After long-term straw returning,the 0-40 cm soil organic matter and total nitrogen content of WP-S was significantly higher than that of WP and CK.(3)The maize plant height,leaf area index and dry matter accumulation showed the trend of WP-S>WP>CK.In the two-year experiment,the yield of WP-S was increased by 67.29 %and 57.06 % compared with that of CK,and the nitrogen accumulation,nitrogen harvest index and nitrogen use efficiency were also significantly enhanced compared with that of WP.In summary,based on the plastic film mulching in dry farmland,taking plow tillage can significantly improve the nitrogen use efficiency of plastic film mulching farmland,and ditch buried straw returning can significantly improve soil moisture and nutrient content,and improve spring maize yield and water and fertilizer use efficiency.