Research On The Evaluation And Methodology Of Reasonable Arable Layer In Maize Dryland With Brown Soil In Northern Liaoning Province

Brown soil is an important soil type of dryland in China,and it is also one of the three major soil types of dryland with optimal soil fertility,water and heat conditions in Liaoning Province.However,this farmland was overused for long-term without maintance measures,resulting in soil organic matter content decreasing,serious soil erosion and lowing and unstable crop yield.It is of great significance for achieving high and stable crop yield,effective utilization of resource to carry out rational quality evaluation of cultivated dryland,clarify the changes of soil quality as well as influencing factors and improve the soil quality of arable land well-directed.In this study,67 field plots with various grain yield of maize yield were investigated in the dryland located in the north of Liaoning with brown soil.Fourteen soil physicochemical indicators of plow layer obtained were used for the principal component analysis to establish a minimum dataset for determining an evaluation system of indicators of reasonable cultivated layer of dryland.The fuzzy comprehensive evaluation method,principal component analysis method,and modified Nemerow index method were used to analyze the evaluation indicators of the reasonable cultivated soil layer.The evaluation results of these methods were tested based on maize grain yield to determine the appropriate method for evaluating the rational cultivated soil layer of brown soil in Liaoning.Finally,the cluster analysis was used to classify the sampling plots.The main results are as follows:(1)There were significant correlations between soil physical and chemical properties according to correlation analysis of the 14 indicators in the evaluation system.Water-stable aggregates,as an important physical indicators reflecting soil structure stability,water holding capacity and permeability,were significantly correlated to the thickness of the plow layer.Soil organic matter with important influence on soil fertility was found negative correlation to soil bulk density,but positive correlation to soil total porosity,water-stable aggregates and alkalytic nitrogen content.There were significantly positive correlations between total soil phosphorus and alkalytic nitrogen,available phosphorus,total nitrogen,and negative correlations between soil total phosphorus and p H as well.(2)The principal component analysis was used to establish a minimum data with dimension reduction of the 14 soil propertiy indicators including plow layer thickness,soil bulk density,total porosity,soil compaction,field water holding capacity,>0.25 mm waterstable aggregates,soil alkalytic nitrogen,available phosphorus,available potassium,total nitrogen,total phosphorus,total potassium,soil organic matter and p H.Then,6 indicators including soil bulk density,soil compaction,field water holding capacity,soil alkalytic nitrogen,total potassium and soil organic matter,were considered into the evaluation system of the plough layer,7 indicators comprising as the thickness of plow pan layer,soil bulk density,soil compaction,>0.25 mm water-stable aggregates,total potassium,soil organic matter and p H were usded for evaluating the plow pan layer,and another 7 indicators containing soil bulk density,>0.25 mm water-stable aggregates,soil alkalytic nitrogen,total potassium,total nitrogen,total potassium and p H were deemed as the evaluation system of the subsoil layer.(3)There were basically similar results from the evaluation methods of fuzzy comprehensive evaluation method,modified Nemerow index method,and principal component analysis method for the soil quality evaluation of arable layer,and the comprehensive quality index was found with extremely and significantly positive correlation with maize grain yield,but with a bit difference among them.According to the comprehensive comparison from the changing range of the evaluatation index and the correlation with maize grain yield from those three methods,the fuzzy comprehensive evaluation method was more suitable for evaluating the rational cultivation layer of dryland.(4)The fuzzy comprehensive evaluation method was used to classify the rationality of plough layer of all sampling plots,and the results of cluster analysis showed that the plough layer quality of survey plots could be divided into 3 levels.According to the summary of the rationality of the arable layer in the survey area,the results showed that the least plots were showed with first-level,only 4.92% of the total survey samples.The most plots were found as second-level followed with third-level plots accounting for 49.25% and 45.83%,respectively.In summary,the arable layer condition of dryland in the brown soil area of northern Liaoning is poor,and the physical and chemical properties of the plow layer in the evaluation system need to be improved through field management techniques to construct a reasonable and suitable plow layer for maize growth for achieving high and stable maize production.