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CORESTA Congress, Shanghai, 2008, APPOST 27

Study on spatial variability and regionalized management of soil nutrients in tobacco plantation field

WANG Xinzhong; ZHANG Zhengyang; LIU Guoshun; HAO Weihong; LI Yantao; LIU Xia; LI Lidan; ZHANG Chunhua
Henan Agricultural University, National Tobacco Cultivate Physiology and Biochemistry Research Centre, Zhengzhou, China.

Present nutrient management for flue-cured tobacco ( Nicotiana tabacum ) in Central China takes no account of spatial variability in soil nutrients. This results in over-application in areas with high nutrient levels and under-application in areas with low nutrient levels. Therefore, understanding the spatial variability of soil nutrients is essential in determining local fertilizer needs of tobacco. The objectives of this study were to (i) quantify the spatial variability of soil properties across tobacco fields and (ii) generate contour maps for regionalized management of these variables. To achieve these objectives, eighty-one soil samples (0~20 cm) were collected from an area of 87 hm2 tobacco field on an approximately 100 m grid in March 2007. Soil properties were analyzed both statistically and geostatistically. The results revealed coefficients of variation ranged from approximately 13% for soil TN and AK to almost 37% for soil AP, indicating the heterogeneity of the nutrient in soil. Soil OM, AP and AK were described quite well with spherical models, whereas AN with exponential model. The correlation distances for soil OM, AN, AP and AK were 447, 337, 345 and 123 m, respectively. The semivariograms were used to generate kriged contour maps, which can be used for the basis of regionalized fertilizer application. Consequently, the whole tobacco field was regionalized into two management zones for nitrogen application, and three management zones for phosphorus and potassium application. This avoids the error of fertilizer recommendation due to the soil spatial variability and makes the soil nutrient management more reasonable.