Study On Phosphorus Fertilization For Winter Winter Production In China And Its Reduction Effect

Phosphorus（P）is one of the necessary nutrient elements for crop growth and development,and it is an important guarantee for grain production.In China’s agricultural production,the phenomenon of excessive input of P fertilizer is very serious.It causes a large accumulation of P in the soil,a large waste of phosphate rock resources,and results in a series of environmental problems（e.g.,eutrophication）.Therefore,it is of great significance to reasonably reduce the application amount of P fertilizer in the current crop production in China.In this study,based on the collection of the literature data on P fertilizer application of winter wheat in China,the temporal and spatial succession of P fertilizer application and winter wheat yield in different plant areas in China were discussed;the potential reduction of P fertilizer input for winter wheat under four levels of soil available phosphorus（AP）（low,medium,high,and extremely high level）in three wheat planting areas（dryland farming area,wheat-maize area,rice-wheat area）was analyzed;and the recommended P application coefficients of winter wheat in each area were determined.In addition,based on a filed experiment of phosphorus fertilizer reduction in the dryland farming area of Yongshou County,Shaanxi Province from2020 to 2022,the aboveground wheat biomass,nutrient contents in each organ,nutrient accumulation,winter wheat yield and its components at jointing,flowering and maturity stages,soil AP content in rhizosphere and non-rhizosphere soils and P budgets were determined,aiming to clarify the feasibility of reducing phosphorus fertilizer application in wheat and provide technical support for wheat phosphorus fertilizer management.The main results are as follows.（1）In different years,with the increase of phosphorus application rate,the average winter wheat yield in three planting areas（dryland area,wheat-maize area and rice-wheat area）in China showed an upward trend.Compared with the application rate of P fertilizer（P₂O₅）at0～50 kg hm^-2,the average wheat yield in dryland,wheat-maize,and rice-wheat areas increased by 383.5～1158.3,1043.7～1823.6 and 1076.3～1671.2 kg hm^-2,respectively when the P application rate was more than 200 kg hm^-2.With the passage of time,the average wheat yield in non-P treatment in various wheat areas also showed an upward trend.Compared with the wheat yield before 1990,the average yield from 2010 to 2021 in dryland area,wheat-maize area,and rice-wheat area increased by 1646.3,1573.0 and 1733.7 kg hm^-2,respectively.（2）With the increase of soil available phosphorus content,the reduction of P fertilizer input for winter wheat in three planting areas showed an upward trend,while the P application coefficient showed a downward trend.Under the same level of soil available phosphorus,the maximum reduction of P fertilizer input in the three planting areas of China were different,and the order is wheat-maize area>dry farming area>rice-wheat area.The reduction proportion of phosphorus fertilizer input in the three planting areas is similar,especially in the low level of available phosphorus soils,with the reduction of 41.28%,40.75%and 40.89%,respectively.The phosphorus application coefficients for wheat in the low,medium,and high levels of available phosphorus soils were 2.6,1.41,and 0.83 in dry farming area,2.7,1.27,and 0.62 in wheat-maize area,and 2.13,0.98,and 0.89 in rice-wheat area,respectively.（3）In the dryland area on the Loess Plateau,the winter wheat yield did not decrease when the application of P fertilizer was reduced from 120 kg hm^-2 to 70 kg hm^-2.Compared with the farmer’s phosphorus application treatment,the balanced P application treatment reduced the amount of phosphorus fertilizer input by 42%,but did not significantly reduce nitrogen,phosphorus,potassium content and their accumulation in the grain,which could ensure the nutritional quality of winter wheat.（4）Based the results of the two-year field experiment,the reduced P application input treatment significantly increased the utilization rate of phosphorus fertilizer by 6.41percentage points,but decreased the available phosphorus content in the non-rhizosphere soil by 22.3%,while it did not change soil total phosphorus.In addition,the farmer’s phosphorus application treatment had an annual P surplus of 28.44 kg hm^-2,while the reduced P application input treatment had only an annual P surplus of 8.88 kg hm^-2,which can significantly reduce the annual soil P surplus by 68.8%.In summary,winter wheat yield and soil phosphorus supply capacity in wheat fields in China increased over the years.Among the winter wheat planting areas,the reduction potential of P fertilzier input in wheat-maize area was largest,and it in rice-wheat area was smallest.In the high level of available phosphorus soils,the recommended phosphorus application rate in dryland area is smallest,and that in rice-wheat area is largest.In the middle and low level of available phosphorus soils,the recommended P application rate of winter wheat in rice-wheat area was the smallest,and that in wheat-maize area was the largest.The reasonably reduction of P fertilizer rate in the medium level of available phosphorus soils in dryland area can still ensure the growth and development of winter wheat,improve the utilization efficiency of P fertilizer,reduce the accumulation rate of soil phosphorus,and maintain the relative stability of soil phosphorus pool.