The Release Of Available Nutrients From Livestock Manures And Effect Of Growth By Manure Application On Winter Wheat

Food security cannot be separated from the support of fertilizer,and the fertilizer industry is also the backbone of agricultural production.However,the production of chemical fertilizer is a large consumer of resources and its application also has a great impact on environmental sustainability.Combined application of organic fertilizer and chemical fertilizer can improve soil,enhance soil fertility,promote crop growth,achieve yield and income increase.China’s annual organic fertilizer resources converted into pure nutrient component is about 75 million tons,equivalent to China’s annual pure fertilizer consumption,but the utilization rate is low.Adding organic fertilizer on the basis of scientific"reducing weight"can reduce the input of chemical fertilizer and promote the full use of organic resources.In this study,organic fertilizer was used as the research object,and the effects of organic fertilizer application on nutrient absorption and yield of winter wheat were studied by combining indoor culture experiment and field experiment.In the experiment of manure cultivation,three kinds of manure were used as experimental materials:pig manure,cow manure,sheep manure,pig-cattle 2:1,pig-sheep 2:1,cow-sheep 1:1.The dosage of organic fertilizer was 150 kg N/ha.Under the constant temperature of 27 ^oC,the experiment was conducted by aerobic cultivation method.In Changwu County,Shaanxi Province,field trials were arranged to study the regulation of organic fertilizer application on nutrient absorption and yield of winter wheat.There’re five treatments:blank control（no application of nitrogen fertilizer）,farmers’habits（195 kg N/ha of urea rate）,nitrogen reduction mode（150 kg N/ha of urea rate）,single application of manure（about 150 kg N/ha of manure rate in nitrogen conversion）,increased application of manure（150 kg N/ha of urea rate,about 150 kg N/ha of manure rate in nitrogen conversion）.The main results obtained are as follows:（1）The indoor culture experiment showed that the change rate of soil nitrate nitrogen concentration was 0.35 mg/（kg·d）,0.65 mg/（kg·d）and 0.42 mg/（kg·d）during 0-14,21-42and 63-84 days,respectively.During 14-21,42-63 and 82-126 days,they were-0.12mg/（kg·d）,0.05 mg/（kg·d）and-0.26 mg/（kg·d）,respectively.The release of ammonium nitrogen of organic fertilizer was concentrated at 0-14 days after cultivation,and the release peak appeared at 7-14 days.The change rate of ammonium nitrogen in soil was 0.12mg/（kg·d）,and the concentration of ammonium nitrogen decreased by 96%at 14-82 days.The peak values of soil P and K concentrations appeared at 14-21 days and 7-14 days,respectively.The change rate of soil P and K concentrations was close to 0 mg/（kg·d）during68-126 days,and only-0.18 mg/（kg·d）during 21-126 days.The concentration of available P and K in organic fertilizer accounted for 20%and 40%of total P and K,respectively.From jointing to flowering（effective accumulated temperature 661-934 ^oC）,the accumulation of nitrogen in winter wheat shoots accounted for 74%of total nitrogen uptake in winter wheat shoots.The change of soil mineral nitrogen in organic fertilizer culture experiment was 51%of the maximum change,which matched with the rapid increase of nitrogen demand of winter wheat.（2）The results of field experiments showed that the soil NO₃^--N concentration was reduced by 77%on average by applying organic fertilizer alone compared with farmer’s habit of applying urea,reducing nitrogen mode and increasing organic fertilizer application.Compared with the nitrogen reduction mode,the soil NO₃^--N concentration in 0-40 cm soil layer with increased organic fertilizer application decreased by 40%at the overwintering stage,but increased by 75%and 55%at the greening stage and harvest stage,respectively.In addition,the nitrate nitrogen concentration in 60-100 cm soil layer was reduced by 72%compared with that in nitrogen reduction,which avoided nitrate nitrogen accumulation in deep soil.For soil NH₄⁺-N,the soil layer at 0-20 cm in overwintering stage increased by29%,the soil layer at 60-80 cm at jointing stage increased by 60%,the soil layer at 0-20 cm at flowering stage increased by 38%,and the soil layer at 20-40 cm at maturity stage increased by 74%compared with the nitrogen reduction mode.（3）Compared with the N reduction mode,the aboveground biomass and N uptake of winter wheat were not significantly affected by organic fertilizer addition,but the root biomass was increased by 45%and 17%at the overwintering stage and the green stage,respectively,and the root N uptake was increased by 29%at the overwintering stage,jointing stage and flowering stage,respectively.As for P uptake in winter wheat,the P uptake in shoot and root increased by 40%and 63%,respectively,in the overwintering period compared with N reduction mode.In terms of K uptake of winter wheat,the amount of k uptake from aboveground by increasing organic fertilizer increased 36%on average compared with farmers’habit and nitrogen reduction mode.From jointing to anthesis,the accumulation rate of K in shoot under N reduction decreased by 35%compared with organic fertilizer application.（4）Compared with the blank control,the root length density in 0-10 cm soil layer at flowering stage increased by 60%on average due to farmers’habits and nitrogen reduction mode,while organic fertilizer application alone had no significant effect.Compared with N reduction,the root tip density and bifurcation density in 0-10 cm soil layer increased by 24%and 34%,respectively.（5）Compared with farmers’habits,there were no significant differences in winter wheat yield,uptake and distribution of nitrogen,phosphorus and potassium in the nitrogen reduction pattern in 2020 and 2021.Compared with N reduction mode,the yield of wheat decreased by 43%with organic fertilizer application alone,but increased organic fertilizer application had no significant effect.Compared with farmers’habits,there was no significant difference in the yield of organic fertilizer application in 2020,and it increased by 22%in2021.In 2021,there was no significant difference between aboveground biomass and farmers’habits,while harvest index increased by 9%.Compared with blank control,the zinc concentration of the four treatments increased 54%on average.There were no significant differences in Fe,Mn,Cu and Zn concentrations in grain under N reduction mode compared with farmers’habits.The concentrations of Fe,Mn,Cu and Zn in winter wheat grains were not significantly affected by increasing organic fertilizer compared with decreasing N.Compared with organic fertilizer alone,the concentrations of Fe,Mn and Zn in grains were not significantly different,but the concentration of cu in grains were 35%and 39%higher,respectively.In conclusion,on the basis of farmers’habits,rationally reducing the amount of nitrogen fertilizer and increasing the application of organic fertilizer can achieve yield increase,and at the same time ensure the stability of the concentrations of large and trace elements in wheat grains.The concentration of available P and K in organic fertilizer was high,which could effectively promote the growth of wheat roots,increase the root tip density and bifurcation density,and enhance the nutrient absorption capacity of roots.The nitrogen in organic fertilizer had a slow release.Compared with the nitrogen reduction mode,increasing organic fertilizer application could effectively reduce the soil nitrate accumulation during winter wheat overwintering period,and increase the soil nitrate nitrogen concentration at wheat jointing stage.In addition,compared with the nitrogen reduction model and farmers’habits,the increased application of organic fertilizer effectively reduced the nitrate nitrogen concentration in deep soil after harvest,and reduced the environmental risk.