Research On Soil Nutrient Spatial-temporal Variability Regularity And Precision Management Zone Division In Black Soil Area Of Central Jilin Province

It is known to all that Black soil is a kind of soil types, with a thick layer of humus and high natural fertility, but the black soil fertility has gradually decreased after affected by the long-term reclamation, plantation and and natural factor. Black soil one of the main soil types and maize is one of the major crops in Jilin Province. In the previous research about the soil fertility change of black soil area, people often focus only on single space and single time. There is not unified sampling scale is in the application of precision farming, spatial-temporal variability characteristics of soil nutrients and field precision management zoning were studied using 3S technology and data mining technology in the process of the implementation of the national 863 project of corn precise operating system research and applications, mastered the spatial temporal distribution characteristics and rules of soil nutrients of black soil area in the middle of Jilin province. This will give the scientific bases to field precision management zoning of black soil area, variable rate fertilizaiton and formulated fertilizaiton in the process of implementation of precision agricultural technique. The main results obtained are summarized as follows:1. Study on the spatial distributing characteristic of soil nutrients in black soil area.By complying regressim-kriging methods to analyze the spatial distribution characteristics of soil nutrients. The results of different regions shown that the spatial distribution of soil alkali-hydrolyzable nitrogenwere and available phosphorus content were enriched from west to east and from southwest to northeast in Yushu and Nongan. The results of same regions shown that soil alkali-hydrolyzable nitrogenwere of Gongpeng Town in Yushu City and available phosphorus content of Kaoshan Town, Helong Town and Shaoguo Town in Nongan County were enriched from south to norht and from west to east. Regions of different levels were combined togehter, local parcels were higher or lower and spatial variability structure was more complex.The spatial distribution state of soil nutrients with different sampling scales shown that distinct spatial distribution similarity in contents of soil nutrients were observed under 40m×40m and 80m×80m grid-sampling scale. Based on this similarity, a variable fertilizaiton prescription map-based was designed directly and applied to the whole process of variable-rate fertilization; medium spatial distribution similarity in contents of soil nutrients were observed under 160m×160m grid-sampling scale and formula fertilization was made and applied to testing soil for formulated fertilization; all things equal; the cost of sampling and workload were reduced in the same circumstance, certain spatial distribution similarity in contents of soil nutrients were observed under 245m×245 mgrid-sampling scale, which was applied to evaluating the soil nutrient status under different soil type or the same type but different fertility soil.2. Study on the spatio-temporal variability characteristic of soil nutrients in black soil area.The soil nutrient of different data sets in Nongan County were studied based on DBSCAN algorithm, the clustering results uped to 90.20 percent accuracy, 89.54 percent accuracy and 94.77 percent accuracy respectively, so as to proved the reliability of the calculating method; the clustering results of soil nutrient in the same data sets shown that the field parcel were classificated into five types, and base on the soil nutrient content of different type and spatial cluster, the whole field parcel were classificated into obvious three types. With continuous variable rate fertilization of several years was conducted in Yushu City, and applied the method of modified K-means clustering algorithm analysis to study of the soil nutrient, the clustering results shown that the classification and proportion of soil nutrient tended to uniformity in the fifth year of variable rate fertilization compared with the third year of variable rate fertilization, the first year of variable rate fertilization and before variable rate fertilization. and shown that the soil fertility achieved balance gradually after variable rate fertilization. With continuous variable rate fertilization for eight years(2005-2012) was conducted in Nongan County and applied the method of FUMF algorithm to analysis the soil nutrient data, the clustering results shown that the soil fertility achieved balance and rise by precision fertilization, a fertilizaiton prescription map-based of 13 th village in Gongpeng Town of Yushu City and Chenjiadian village in Helong Town of Nongan County was designed, it also provided the technical support for field precision management zoning and precision fertilizaiton decision-making.3. Study on the spatial-temporal variability and the correlation between the of soil nutrients and mazie yield.Analysis from maize yield and spatial variability characteristics of soil nutrients showed that the variation were high between maize yield and spatial variability of soil nutrients under different years and soil fertility conditions. The relationship between mazie yield and spatial variability of soil nutrients showed that there appeared some correlation between spatial variability of mazie yield and spatial variability of soil organci matter and some available nutrients.4.Study on the soil fertility evaluation and field precision management zoning based on spatio-temporal clustering algorithm.With continuous variable rate fertilizaiton for seven years was conducted in 3rd field of 13 th village in Gongpeng Town of Yushu City, the results of exploratory temporal and spatial data processing shown that the noticeable correlativity of soil nutrients were observed. Applied the method of fuzzy clustering analysis to study of the soil nutrient classification in Chunyang Village of Gongpeng Town in Yushu City of Jilin Province, the results shown that the parcels was classified into three type site-specific management. The soil fertility was comprehensively evaluated by using Time Series analysis, the results shown that the difference of soil fertility began to flatten with continuous variable rate fertilizaiton for several years; With continuous variable rate fertilizaiton for three years was conducted in Nongan Town, Helong Town, and so on, the spatial-temporal clustering results of sample data also shown that the soil fertility status has been improved after precision fertilization, and with the results for field precision management zoning.