Study On The Index And Evaluation System Of Accurate Management Of Phosphorus In Maize And Rice In Liaoning Province

Improving fertilizer use efficiency,realizing nutrient efficient management and producing more grain with minimum environmental cost are the main challenges which facing our country.At present,the recommended fertilization method research on soil supply component cannot quantitatively analyze the soil supply component of the field.Based on the soil phosphorus supply（Ps）as the breakthrough point,this paper reveals the main control factors and variation mechanism of phosphorus fertilizer utilization rate（PUE）,looks for new variation ways and rules,realizes the prediction of phosphorus fertilizer utilization trend,looks for the method of controlling phosphorus fertilizer utilization rate,and constructs the index and evaluation system of phosphorus precise management.In this paper,based on the results of multi-year and multi-point field experiments on phosphorus fertilizer efficiency of maize and rice at 65experimental sites in Liaoning Province from 2006 to 2010,the quadratic term model,linear plus platform model,spherical model and exponential model were used to calculate the optimal phosphorus application rate and target yield of the two crops after data processing.From the perspective of phosphorus fertilizer utilization rate of maize and rice,we can better understand the law between crop demand and fertilizer supply.By studying the variation mechanism of fertilizer utilization rate,we can determine the soil supply component,establish the index and evaluation system of phosphorus precise management,and provide scientific guidance and theoretical basis for the construction of farmland precise nutrient management system suitable for agricultural production in Liaoning Province.The main research results are as follows:（1）In the field fertilizer efficiency test of maize phosphate fertilizer,the fitting degree from high to low was quadratic model>spherical model>exponential model>linear plus platform model.In the field fertilizer efficiency test of rice phosphate fertilizer,the fitting degree from high to low was quadratic model>exponential model>spherical model>linear plus platform model.（2）The index model had the lowest recommended fertilization amount and higher yield,and the highest utilization rate of phosphorus fertilizer.In the soil with low,medium and high nutrient levels,compared with the quadratic model,the average P application rates of maize decreased by 58%,55%and 57%,respectively.The average phosphorus application rate of rice decreased by 67%,61%and 15%respectively.Compared with the spherical model,the average phosphorus application rate of maize decreased by 52%,55%and 63%respectively.The average phosphorus application rate of rice decreased by 64%,59%and 62%respectively.Compared with the linear plus platform model,the average phosphorus application rate of maize decreased by33%,45%and 27%respectively.The average phosphorus application rate of rice decreased by 62%,37%and 46%respectively.Index model can be used as the best model of recommended fertilization for maize and rice in Liaoning Province.（3）Phosphorus supply capacity（PRSC）was used to represent the competitive relationship between soil nutrients and fertilizer nutrients.High soil nutrient supply component would dilute fertilizer nutrients and reduce the effectiveness of fertilizer nutrients.Crop phosphorus starvation degree（CPSD）was used to represent the supply and demand relationship between soil nutrients and crops.The two variation pathways of phosphorus use efficiency are crop phosphorus starvation degree（CPSD）and fertilizer relative supply capacity（PRSC）,both of which are indirectly affected by soil supply components.Therefore,measures to improve agronomic efficiency can be carried out by improving crop nutrient demand management and optimizing fertilizer nutrient supply management.（4）The three main controlling factors affecting the utilization rate of phosphorus fertilizer are soil supply component,phosphorus-free area yield,recommended fertilization amount and the interaction of the three.Establish phosphorus fertilizer utilization model:Maize:Y=3.373+0.836X₁-10.063X₂-0.108X₁X₂+4.523X₂²Rice:Y=1.059+0.911X₁-7.681X₂-0.197X₁X₂+5.413X₂²The fitting degree of the above model is high,which can be used as a reference index for phosphorus fertilization of maize and rice in Liaoning Province to provide a theoretical basis for accurate management.（5）We established a quadratic polynomial regression model with the degree of phosphorus starvation（CPSD）and the relative supply capacity of fertilizer（PRSC）as the independent variables of crops,and the utilization rate of phosphorus fertilizer as the dependent variable,as follows:Maize:Y=3.373+0.836X₁-10.063X₂-0.108X₁X₂+4.523X₂²Rice:Y=1.059+0.911X₁-7.681X₂-0.197X₁X₂+5.413X₂²The two variation pathways of phosphorus use efficiency are crop phosphorus starvation degree（CPSD）and fertilizer relative supply capacity（PRSC）,both of which are indirectly affected by soil supply components.Therefore,measures to improve utilization rate can be carried out in two directions:improving crop nutrient demand management and optimizing fertilizer nutrient supply management.