Effects Of NPK Fertilizer Management On Wheat Yield And Nutrient Use Efficiency Under Rice Straw Returning

The crop straw is rich in nitrogen,phosphorus and potassium and other nutrients,and straw incorporation is an important way of nutrient input in farmland.Anhui Province is the main wheat production province.Rice-wheat rotation is the main production mode of wheat along Huaihe River and Jianghuai region in Anhui Province.Direct crushing and returning to the field is the main way to utilize rice straw resources in this area.It is of great significance to improve the yield and nutrient utilization efficiency of wheat by applying fertilizer under straw incorporation.In this study,two-year field localization experiments were conducted to investigate the optimal base-dressing ratio and the potential of phosphorus-potassium fertilizer application.The present research provide a theoretical basis for the scientific application of nitrogen,phosphorus and potassium fertilizer in wheat under rice straw return.The main findings are as follows:1.With the decrease of nitrogen basal-topdressing ratio,the nitrogen content and accumulation in wheat plants increased first and then decreased.When the nitrogen basal-topdressing ratio was 6:4,wheat plants had the highest nitrogen accumulation in2018(the content range was 1.13 ? 27.22 mg per plant,corresponding to a mean value of15.86).Under the condition of straw incorporation,the application of nitrogen fertilizer had an effect on the effective panicle number and the grains per panicle in 2018,which increased by 7.0% and 7.7% respectively,compared with formula fertilizer(basal-topdressing ratio 7:3)when the ratio was 6:4,but there was no significant influence on 1000-grain weight.The yield of wheat was the highest in the treatment of nitrogen basal-topdressing ratio 6:4.Under the condition of straw incorporation,the nitrogen basal-topdressing ratio at 6:4 can improve the agronomic efficiency,partial productivity and absorption efficiency of nitrogen fertilizer in wheat.In the process of straw incorporation,when the amount of nitrogen applied is the same,the nitrogen basal-topdressing ratio is 6:4,which can promote the growth and increase the wheat yield.2.The phosphorus content and accumulation of wheat plants increased first and then decreased with the decreased amount of the phosphorus fertilizer,and the content of available phosphorus in soil decreased first and then increased.When the phosphorus fertilizer was reduced by 20%,wheat plants had the highest phosphorus accumulation in two years.The phosphorus content ranged from 0.31 to 6.38 mg/plant in first year and from 0.14 to 5.31 mg/plant in second year,and the corresponding mean values were 2.56 and 2.55 mg/plant,respectively.The corresponding content of soil available phosphorus ranged from 24.56 to 29.86 mg/kg and from 15.72 to 30.59 mg/kg,and the corresponding mean values were 27.08 and 22.65 mg/kg,respectively in mature stage.Under the condition of straw retention with formula fertilization,the amount of phosphorus fertilizer application had no significant effect on the effective panicle number,the grains per panicle and 1000-grain weight in the first year but had a significant effect on the effective panicle number in the second year.Wheat yield was highest with 20% phosphorus reduction in two years.The reduction of phosphorus fertilizer within 20% with rice straw incorporation increased phosphorus agronomic efficiency,partial productivity of phosphorus fertilizer and phosphorus utilization efficiency in wheat plant,whereas it has no significant impacts on wheat yield(P > 0.05).The amount of phosphorus fertilizer reduced by less than 20%in the soil with the rice straw incorporation including the high available phosphorus(> 20mg/kg)would not affect the normal growth and yield in wheat for two consecutive years.3.The content and accumulated amounts of potassium in wheat plant were firstly increased and then decreased as the potassium fertilizer was reduced from 10% to 30%.The highest amounts of potassium in wheat plant were found with the reduction of 20%potassium fertilizer.The content of potassium range was from 2.70 to 26.32 and from 1.78 to 31.42 mg/plant,and the corresponding mean values were 18.45 and 18.90 mg/plant,respectively.The soil available potassium concentrations ranged from 235.00 to 317.25 and from 206.67 to 303.33 mg/kg,and the corresponding mean values were 268.35 and239.75 mg/plant,respectively.The soil total potassium content was 23.60 and 23.40 g/kg in mature stage,respectively.The reduction of potassium fertilizer from 10% to 30% with rice straw return has no significant influences on the grains per panicle and 1000-grain weight,whereas effective panicle number was firstly increased and then decreased.Compared with the recommended potassium fertilization treatments,the reduction of potassium fertilizer within 20% after rice straw incorporation increased potassium agronomic efficiency,partial productivity and potassium utilization efficiency in wheat plant,whereas it has no significant impacts on wheat yield(P > 0.05).Generally speaking,the 20% reduction amount of potassium fertilizer would not affect the normal growth and wheat yield with rice straw return which included high available potassium(> 180 mg/kg)for two consecutive years,whereas it increased potassium utilization efficiency in wheat plant.