Spatial Distribution of Soil Zinc Deficiency in Brahmaputra Plain, India

Abstract

Analysis and interpolation of soil properties is very important for site specific management. The objective of this study was to determine the spatial distribution and degree of risk of Zn deficiency in Brahmaputra plains, Assam, India using statistics and geostatistics. A total of 5,494 soil samples were collected using I km x I km grid at 0-25 cm depth from three district namely Tinsukia, Morigaon and Nalbari representing upper, central and lower Brahmaputra plains covering 6,249l<rrt2 arca and analyzed for pH, organic carbon (OC) and Zn (DTPA). Data set was normally distributed. Geostatistical analyses were carried out, including experimental variogram and model fitting. The ordinary kriging spatial distribution map showed that the Zn (DTPA) is deficient for agricultural crops in the all the three zones of Brahmaputra plains. The probability map produced based on indicator kriging showed that there is a chance of Zn deficiency in crops in 34Yo area of the Tinsukia, 70Yo area of the Morigaon and,85Yo area of the Nalbari district. The standard deviation (SD) rnap generally showing the SD values are high for the areas that are far away from the sampling sites. The correlation analysis showed that Zn (DTPA) is highly, significantly, and positively correlated with oC (t : 0.279 * * ) and highly significantly negatively with pH (r : -g.lfpx *) in Brahmaputra plains. Thus, the study will help to minimize both yield loss and environmental threats such as Zn toxicrty due to under or over dose of Zn fertllizer application in the Brahmaputra plains.