Spatialization of Actual Grain Crop Yield Coupled with Cultivation Systems and Multiple Factors: From Survey Data to Grid

The spatialization of actual grain crop yield helps to understand the spatial heterogeneity of yield and support for the precise farming and targeted farmland management. However, inadequate consideration and quantification of anthropogenic factors affecting the estimation of actual yield distribution easily cause uncertainties in recent researches. Here, we developed a new grain crop yield spatialization (GCYS) model in order to downscale the yield from county to grid scale. The GCYS model is composed of four modules: (a) cultivated land Net Primary Productivity (NPP) calculation module, (b) comprehensive agricultural system construction module, (c) key factors establishment module, and (d) integration and validation module. Its novelty is to realize the actual grain crop yield spatialization from county scale to grid scale by quantifying and spatializing the comprehensive agricultural system when considering the diversity of cultivated structure and field management factors. Taking Guizhou and Guangxi Karst Mountains Region as a study-area, the GCYS model is developed and tested. The determination coefficients of regression analysis between agricultural survey data and spatialization results of paddy rice yield calculated by our model reach 0.72 and 0.76 in 2000 and 2015, respectively (p < 0.01). The results visualize the spatial pattern of actual grain crop yield at the grid scale, which show a gradually decreasing trend from southeast to northwest. With an increase in potential yield and improvement of field management technologies, the actual average yield of grain crops per unit increased form 4745.10 kg/ha of 2000 to 5592.89 kg/ha of 2015. Especially in high-yield zones in southeast area, mechanized cultivation became the dominated factor, rather than chemical fertilizer application. This demonstrates that our model can provide a reference for agricultural resource utilization and policy-making.