Abstract: Low-hilly red soil regions are important grain production areas in Zhejiang province.Theyhave abundant climatic resources and great productive potentials,but compared with highproductive areas in the province,the conversion ratio of input energy and the photo-utilization efficiency of grain crops are significantly lower.These regions are characterized byhigher crganic fertilizers input,which accounts for 70% of the total energy input for grainproduction.Balances between nutrient elements become more important in the grain production areas.

Key words: total radiation, photosynthetically active radiation, observation error, radiometer performance, ChinaFLUX