Selection Of Soil Samples For Rapid Evaluation Of Cultivated Land Quality In County

Food security is an important foundation for maintaining human survival,maintaining social stability and safeguarding national security.Since the reform and opening up,China's economic level has risen rapidly,but with the continuous reduction of cultivated land area and the declining quality of cultivated land,these have posed a threat to China's food security(Li Ling et al.,2015).In recent years,China has the exact measures and policies for the protection of cultivated land quantity,and has formed a relatively mature system and obvious results.Under this background,the quality protection of cultivated land has been paid more and more attention.In order to improve the quality of cultivated land in China and better serve the quality management of cultivated land,it is necessary to quickly grasp the change of cultivated land quality and improve the efficiency of cultivated land quality change evaluation.In order to improve the efficiency of regional arable land quality evaluation and to ensure the quality of cultivated land in the region,the quality of cultivated land in the county is very good,and the quality of cultivated land is improved.Quantity-quality management of the implementation of both.In this paper,Donghai County is selected as the study area.Based on the data of cultivated land fertility survey,the quality of cultivated land is supplemented with good results and remote sensing data,the K-means clustering method is used to divide the plots of cultivated land in the whole study area,Paddy field,irrigated land and dry land),distinguishing between topographic grid(hillock area,transition zone and gentle slope area),and the accuracy of each cluster result was evaluated.Finally,the best poly The results show that the soil properties of the landscape type area are calculated by using the multi-plaque data representative method,and the soil property index of the cultivated land based on the landscape type is obtained.The paper chooses the quality of the cultivated land in the county to evaluate the quality of the cultivated land.The final selection of the sample selection scheme is carried out.And provide some methods for the evaluation of cultivated land quality.The paper draws the following main conclusions:(1)Based on the relationship between the average cluster radius and the centroid distance and the number of categories,the optimal clustering results of the landscape factor are 9,and the landscape type is formed,which is the quality of the cultivated land.Evaluation of soil samples to provide the basis for selection.In the study area,the average cluster radius and centroid distance of the study area showed a linear relationship with the number of categories.In the SPSS software,78939 plots were clustered and analyzed by K-means clustering analysis.The results show that the optimal clustering K value is obtained from the two groups,and the optimal clustering number is 9,and the distance from the subspace grid(paddy field and paddy field)The results show that the optimal clustering of landscape factors in the study area is 9,and the landscape type area is divided into three types:The quality of cultivated land is quickly evaluated by the selection of soil samples.(2)On the basis of this paper,a representative sample scheme based on different soil properties was formed,which was composed of 79 samples of organic matter.Point,pH value of 50 samples and clay content of 116 samples,and based on the integrated soil properties based on the representative of the sample selection program a total of 47 samples.In this paper,the representative data of multi-plaque data were used to calculate the soil organic matter,pH value and clay content in the patch of the landscape type.On this basis,two quick sample selection methods were adopted:One is the use of the landscape type area of the internal grid of soil organic matter,pH value and clay content of the strongest representative of the 84,52 and 120 plaques and cultivated land fertility survey samples were superimposed on the landscape type of different soil The results showed that 79,50 and 116 samples were selected,and the samples were selected based on the representative values of different soil properties.The second was to determine the soil organic matter in the study area according to the"Regulations",The weight ratio of pH value and clay content is 0.52:0.16:0.32,and the comprehensive soil properties of the interior grid of the landscape type area are calculated,and the comprehensive soil properties in the type area are calculated.There were 47 plots,and 47 samples were collected with the soil samples of cultivated land.(3)The sample selection scheme based on the representation of different soil properties and the sample selection scheme based on representative representative of soil properties and the sampling of all the sampling points of cultivated land fertility were carried out respectively.The results showed that the representative values of soil samples were based on different soil properties The results of the selection plan are closer to the cultivated land quality supplement and improve the results,the relative evaluation accuracy is also higher.Study with reference to "agricultural land quality classification rules"(GB/T 28407-2012)(hereinafter referred to as the "Regulations"),the sample selection scheme based on the representation of different soil properties and the sample selection scheme based on the representative representative of the soil and Evaluation of Cultivated Land Quality in Cultivated Land.The results showed that the result of representative sampling scheme based on different soil properties was 0.863,which was the same as that of cultivated land quality evaluation based on cultivated soil fertility survey.The precision was the highest.Based on the comprehensive selection of soil samples,The accuracy of the evaluation is 0.723,but R2 is also larger than 0.7,and the precision is higher.The number of samples in investigation of cultivated land fertility is 800.And Based on the representative of the different soil properties of the sample selection of organic matter 79 samples,pH 50 samples and clay content of 116 samples.Based on the comprehensive selection of soil samples representative sample program a total of 47 samples,therefore,in the requirements of precision under the premise of the county farmland quality changes quickly selected should be based on different soil properties representative Sample selection program;and in the requirements of the number of samples at the same time to ensure the accuracy of the premise should be based on the comprehensive selection of soil properties representative of the quick evaluation sample selection program.