GIS-based Variable-rate Management Zone Of Soil Nutrients For Tobacco Field In Different Period

ABSTRACT:Soil is a breeding base for plants, which provides essential nutrients for plant growth. Soil not only has a clear spatial variation, but also has a certain change in time. It is the foundation to divide the rational nutrient management zones,for achieving the precise management of tobacco soil and Improving the quality of tobacco.This study which uses GPS, chooses5hm2tobacco field respectively in Xuchang campus of Henan agricultural University in April and October, employ20x20grid method in sampling260soil samples. It can analysis of soil nutrients by using GIS and geostatistics and get a variety of soil nutrient data to execute fuzzy c-means clustering. The main findings are as follows:(1)The soil within the study region, soil pH7.45and7.54respectively in the two periods. In April, organic matters (OM)19.08mg/kg, available N (AN)87.25g/kg, available P (AP)9.27mg/kg, available K (AK)178.32mg/kg.OM and AN content are low, AP content is moderate, AK content is high. In October, OM20.03mg/kg,AN71.91g/kg, AP8.96mg/kg,AK196.84mg/kg. AP and AN content are low,OM content is moderate,AK content is high. In the two periods, Fe and Mn content are moderate, Cu and Zn content are affluent. That is the soil is slightly acidic with a pH variation coefficient2.43%and2.55%. The remaining nutrients have varying degrees of variation, in the range between2.43%-61.69%in April and between2.55%-51.53%in October.(2) In this study region,the properties of soil are all in accordance with normal distribution, except for the AP of April and October, The data of the AP accords normal distribution, after logarithmic transformational, so the stationary hypothesis satisfies. The difference of correlation distance is bigger between29.4m-595.2m.The correlation distance of available Mn is29.4, which is the closest, the farthest is AK in April. The Correlation distances of all indicators are greater than20m, this means that it is possible to use the spacing of20m×20m.(3)In the research region in April, the Co/Co+C of pH, AP, available Mn and available Zn are18%,8.5%,6.2%and7.1%.In October the Co/Co+C of pH,AN,AK, available Mn and Zn are18.2%,7%,6.7%,6.7%and5.4%,which have an intense spatial correlation. The Co/Co+C of available Cu in October is93.37%, which has a weaker spatial correction. The other Co/Co+C are between30%-50%with a moderate spatial correlation.(4)Extracting two principal components whose eigenvalues>1.The main representations of PC1which can explain40%of total variance are OM,AN,AP,AK, available Mn. The main representations of PC2which can explain18%of total variance are pH, available Fe and available Cu.Therefore,PC1has a higher similarity with OM,AN,AP,AK and PC2has a higher similarity with available Fe and Cu.(5) This study determines the optimal number of partitions in the region is4, by using fuzzy performance index (FPI) and normalized classification entropy (NCE). The test shows that the soil nutrients have highly significant correlation.