Kriging is a method of estimating values of properties at places without bias and with minimum error from observed values in the neighbourhood.The method was applied to measurements of total nitrogen in the top layers of the soils in Zhangwu County in China.After transforming the measurements to logarithms to stabilize their variances,the semi-variogram was computed from them.The semi-variogram showed spatial dependence extending to 50 bm,although it had a large non-spatial,or "nugget" component.Mathematical models were fitted,and the one giving the best fit in a least square sense was used to estimate values and their estimation variances on a fine grid(1.25km) from which isorithmic maps of the county were drawn.