Abstract: Abstract: The farmlands in South Jiangsu province in China usually have characteristics of small acreage with fixed field boundary, balanced fertility inside one field plot and possibly significant fertility difference among different field plots even though some plots are close to each other. The reason for this phenomenon is that farmlands have been already assigned to rural families in small-scale-size plots for decades and the field plots are farmed by rural families independently. Rural families have a good understanding of overall soil fertility and yield potential about their own field plots, but they are not very clear about the matching relationship of target plant production and the needed amount of fertilizer for each field plot. According to the characteristics of farmland plots and the technical barriers of carrying out variable rate fertilization in South Jiangsu province, a simple executable scheme of variable rate fertilization was proposed in this paper. This scheme referred to a rough production-fertilization relation model which was established based on the "target output and fertilizer amount" theory by local government's agricultural departments in South Jiangsu Province. The final scheme for variable rate of fertilizer application is based on yield potential and target production data of the field plots. Using this scheme, the soil fertility of the field plots were classified into different grades. The target production of the field plots were discretized into finite data sets which were corresponding to different target amount of fertilizer application. Implementing this scheme for variable rate of fertilizer application was expected to obtain these effects: uniform application of fertilizer inside one field plot and adjusting the amount of fertilizer application to meet the actual needs of different field plots. The fertilizer-seeder machine for variable rate application, which was equipped with an electronic prescription map system based on the scheme of variable rate fertilization, was renovated from a mechanical sowing machine into an automatically operating system. The renovated system has the ability to automatically sense the working place site and the forward speed in field, and automatically adjusts the flow rate of the seeders with the help from the electronic prescription map system. With single crop field plot which has naturally-formatted boundary as a basic processing unit, the variable rate fertilizer-seeder which was equipped with an electronic prescription map system has the function as following: automatically mixing various fertilizers together as needs, uniform application of fertilizer inside a natural field plot and variable rate fertilization among different natural field plots. In order to further improve the precision quality and working stability. The data from the ordinary precision GPS model were processed with the methods of differential treatment and Kalman-filtering, which can reduce the data fluctuation caused by noise signal. The structure of fertilizer seeder with outer slots was optimized, which can efficiently reduce the edge leakage of fertilizer seeder and improve the flow rate consistency of the fertilizer seeder. Field experiments results showed that the operating outcomes of the electronic prescription map system were correct, the variable rate fertilizer seeder had a stable working state, the biggest and averaged amount errors were correspondingly 3.91% and 2.09%, while the biggest and averaged dynamic errors were correspondingly 4.52% and 1.48%. The research results can be the reference for implementing variable rate fertilization in small-scaled fields in South Jiangsu province in China.