Effects Of Nitrogen Reduction Combined With Mulching On Yield And Nutrient Absorption And Utilization Of Winter Wheat

Studying the regulation of nutrient accumulation and transfer of dryland winter wheat under the combination of nitrogen fertilizer reduction and different mulching measures,so as to ensure the good quality and high yield of dryland winter wheat in northwest China.This experiment was conducted from 2012 to 2017,with no nitrogen fertilizer as the control,two models were set up,one is farmers'model(the amount of nitrogen fertilizer used is 195kg·hm^-2),another is farmers'nitrogen reduction model(the amount of nitrogen fertilizer used is 150 kg·hm^-2).On the basis of applying 150 kg·hm^-2 nitrogen fertilizer,ridge-mulching and furrow-seeding,plastic mulching,and straw mulching were set up for three kinds of surface covering treatments,with a total of six treatments.The grain yield and biomass of winter wheat in five seasons were measured.Dry matter,accumulation and transfer regulation of nitrogen,phosphorus and potassium in each treatment were determined and studied from2016 to 2017.The results obtained are as follows:1.According to the average yield and biomass of five seasons in 2012-2017,compared with the farms'model,the farmers'nitrogen reduction has a downward trend in grain yield and biomass,but it had not reached significant level.On the basis of nitrogen reduction,ridge-mulching and furrow-seeding showed a trend of increasing yield,and the biomass of plastic mulching and straw mulching treatments increased by 8.4%and 5.0%,respectively,compared with that of the farmers'nitrogen reduction.The biomass of ridge-mulching and furrow-seeding,plastic mulching and straw mulching treatments increased by 7.1%,15.5%,10.0%,respectively,compared with farmers'nitrogen reduction.It can be seen that nitrogen fertilizer application rate of 150 kg·hm^-2 can basically meet the growth demand of dryland winter wheat,and it's feasible to reduce nitrogen fertilizer application.After applying ninitrogen fertilizer,stems and leaves accumulated a large amount of dry matter,which promoted the transfer of dry matter.Dry matter transfer in straw mulching treatment was negative,which indicated that straw mulching didn't significantly promote the synthesis of dry matter before flowering.2.According to the data from 2016 to 2017,compared with the farmers'model,there was no significant difference in nitrogen accumulation,transfer amount,transfer rate and transfer contribution rate of nitrogen reduction treatment.Compared with the farmers'nitrogen reduction treatment,there was no significant difference in nitrogen accumulation,transfer amount,transfer rate and contribution rate of transfer nitrogen under three kinds of mulching treatments,the nitrogen uptake of grain and nitrogen harvest index had a downward trend under three kinds of mulching treatments.When nitrogen fertilizer was applied,the nitrogen transfer amount and the contribution rate of nitrogen transfer to grain increased with the increase of nitrogen application amount,and the influence of surface mulching on nitrogen transfer was not obvious.Applying nitrogen fertilizer can greatly improve the nitrogen accumulation in different growth stages of winter wheat;and it can also affects the total nitrogen uptake and grain nitrogen uptake amount of winter wheat in harvest time,and the degree of influence is related to the amount of fertilization.The utilization rate of nitrogen fertilizer,agronomic efficiency of fertilizer nitrogen and physiological efficiency of fertilizer nitrogen decreased with the increase of nitrogen application rate.There was no significant change in nitrogen use efficiency of three kinds of surface covering treatments compared with farmers'nitrogen reduction treatment,but there was an increasing trend in fertilizer nitrogen agronomic efficiency.3.The application of nitrogen fertilizer in this experiment significantly improved the phos phorus transfer from stem and leaf to grain,amount and rate of phosphorus transfer increased with the increase of nitrogen fertilizer dosage.Ridge-mulching and furrow-seeding and plastic promoted the accumulation and transfer of phosphorus.Under straw mulching,the accumulat ion of phosphorus increased significantly,Phosphorus accumulated in flowering period under s traw mulching was less,so transfer amount of phosphorus,transfer rate and contribution rate of transferred phosphorus to grain were all lower.4.Potassium transfer increased with the increase of nitrogen fertilizer dosage,and the mo re potassium was lost after anthesis.Ridge-mulching and furrow-seeding and plastic promoted the accumulation and transfer of potassium.Under straw mulching,the accumulation of potas sium increased significantly,and the transfer and loss of potassium were lower.However,the p ercentage of grain potassium in transferred potassium is higher,which indicates that potassiu m in transferred seeds can be well preserved under straw mulching treatment.