evaluation of spatial variability of availalable iron and affecting factors on it in paddy soils (case study: central paddy fields of guilan)

iron is an essential nutrients in rice. accurate assessment of this element in paddy soils is very important. improving fertility management, accurate interpolation, being aware of spatial variability and patterns of distribution of micronutrients are the most important factors in soil management and accurate consumption of fertilizers. this study was done for investigating of available iron, determining the impressive soil factors and choosing the best interpolation method for determining spatial variability of plant available iron in 162 soil samples of the paddy fields in central guilan. estimating and interpolation of variables were investigated with kriging and inverse distance weighting (idw) methods in power one to four and the best interpolation method was chose using evaluating statistics such as me and nrmse. organic carbon, clay and soil ph by controlling soil reduction conditions had the most effect on available iron. variability of available iron had a random shape in the study area and spatial dependency of these variables was weak. therefor inverse distance method was prosperous than kriging for interpolation of available iron. spatial variability of available iron in the study area showed that high concentration of available iron was in soils with acidic ph and low concentration observed in soils with light texture and approximately neutral ph. so, in order to retain the amount of available iron in the study area, usage of iron fertilizers based on site specific management is necessary.