Screening And Application Of Different Optimized Fertilization Measures To Improve Phosphorus Utilization Efficiency Of Winter Wheat In Dryland

In the wheat production in Weibei dryland of Loess Plateau,drought and water shortage,low soil fertility,and unreasonable fertilization methods are the main limiting factors affecting the yield of winter wheat and the improvement of phosphorus（P）fertilizer utilization rate.Herein,two field experiments were carried out in Yongshou County,Shaanxi Province.Under the amount of P fertilizer input based on P balance and environmental conditions,there were control treatment（no phosphorus fertilizer,CK）,balanced P application mode（BP）,banding P application mode（optimized measure 1,BF）,ammonium sulfate mode（optimized measure2,SA,ammonium sulfate instead of urea）,supplementary irrigation mode（optimized measure3,SW）,film mulching mode（optimized measure 4,RM）,biochar mode（optimized measure5,BA）,organic fertilizer mode（optimized measure 6,OA）treatments.The wheat plant and soil samples were collected at the regreening stage,jointing stage,heading stage（flowering stage）and maturity stage of winter wheat.The wheat root morphology,P content in different organs,soil p H,soil available nutrients,soil enzyme activities and wheat yield and biomass were determined.Then principal component analysis method was used to evaluate the different measures and choose an appropriate measure.The objectives were to reveal the effects of different P fertilizer optimization modes,find out the best P fertilizer management mode for improving the yield of winter wheat and the utilization rate of phosphorus fertilizer,and provide scientific basis and technical specifications for high yield of wheat and efficient utilization of phosphorus fertilizer in Weibei dryland of Loess Plateau.The main results are as follows:1.The balanced P fertilization based on phosphorus P balance and environmental conditions reduced the input rate of P fertilizer and maintained the wheat yield and biomass.In the wheat season of 2018-2022,compared with the CK treatment,the balanced P application（BP）treatment（P₂O₅ 70 kg/hm²）significantly increased the wheat grain yield and biomass by13.41%and 11.24%,respectively.Compared with the BP treatment,all optimized P fertilization treatments increased the wheat yield and biomass by 8.07%～15.24%the grain P content by 2.49%～18.52%,and the partial productivity of P fertilizer（PFP）by 2.61%～7.97%.Therefore,optimizing P fertilizer application measure is an effective way to increase wheat yield and improve P fertilizer utilization rate in dryland.2.Compared with the BP treatment,the supplementary irrigation（SW）treatment increased the precipitation utilization efficiency by 12.79%,the P fertilizer recovery utilization rate by 3.77 percentage points,and PFP by 8.24%.The BF treatment significantly increased rhizosphere soil available phosphorus content by 67.39%～103.26%at the regreening,jointing and maturity stages,but most of root morphological indexes were lower than those in the BP treatment at jointing and heading stages,indicating that banding application of P fertilizer had no significant effect on wheat root growth.The SA treatment significantly reduced non-rhizosphere soil p H by 0.09 units,and water consumption by 3.77%.3.Compared with the BP treatment,the RM treatment significantly increased root length and root surface area by 61.38%～90.69%and 42.93%～79.32%,respectively,at regreening and jointing stages,soil available P（148.11%～190.44%）and total P content（19.65%）in the rhizosphere soil from the regreening stage to the mature stage.The RM had a significant effect on reducing non-rhizosphere soil p H.In addition,the RM also significantly increasedβG enzyme activity by 0.25%and 162.5%at jointing and anthesis stages.The BA treatment significantly increased the content of available potassium in non-rhizosphere soil and rhizosphere soil by 11.13%～35.24%at maturity stage,soil total carbon content by 16.7%,organic carbon content by 27.8%,organic matter content by 37.49%,and PHO,βG,NAG,βX enzymes activity involved in the carbon,nitrogen and phosphorus cycle at jointing and anthesis stages,which was beneficial to improving soil quality.In addition,the BA treatment significantly increased the recovery rate of P fertilizer by 6.39 percentage points,PFP by 7.97%and the agronomic efficiency of P fertilizer by 58.2%.The OA treatment significantly increased the P uptake in stems and leaves by 13.8%,available phosphorus content in non-rhizosphere soil and rhizosphere soil by 20.9%～71.4%and 14.4%～52.3%,respectively at regreening and maturity stages.4.The spike number per hectare,grain number per spike,1000-grain weight,root average diameter,grain P content,grain P absorption,rhizosphere soil available P,wheat yield,and recovery rate of P fertilizer were chosen to perform principal component analysis and the results showed that the comprehensive score of three principal components in all indexes was more than 1.The optimal fertilization mode was film mulching（RM）,followed by BA mode.In summary,in winter wheat production in Weibei dryland of the Loess Plateau,the application rate of P fertilizer at P₂O₅ 70 kg/hm² ensured the wheat yield and biomass.The film mulching measure（RM）promoted the wheat root growth and development through heat preservation and storage,thereby increased wheat yield.The addition of biochar combined with nitrogen and phosphorus fertilizer（BA）had a significant improvement effect on soil total carbon,organic carbon,and organic matter content,which is beneficial for improving soil quality.The organic fertilizer plus nitrogen and phosphorus fertilizer（OA）increased soil phosphorus availability and nutrient absorption and utilization thus promoted winter wheat yield.Therefore,the balanced P fertilizer management（P₂O₅ 70 kg/hm²）is an effective way to achieve high wheat yield and P fertilizer efficiency in Weibei dryland.The P fertilzier application rate combined with film mulching measure,biochar and organic fertilizer can be used as a feasible phosphorus nutrient management technology to achieve high P use in winter wheat production in this area.