Abstract: Investigation shows:(1)fertilizers are the main way of N,Pand Kinput in the rice areas,return back as crop residues is also one of the important nutrient resources,and biologicaInitrogen fixation is one of the important nitrogen resources. Harvest is one of the important output ways for N,Pand K,and loss of nitrogenous gases is another important output way for Nin the rice areas;(2)rice-based cropping system in eastern and central China tends to be more inorganic agriculture than that in southern and southwestern China.The degree of organic agriculture in southern China is the highest in the three rice areas;(3)the inputs and outputs of N, Pand Kunder major rice-based cropping systems in subtropical zone of China are basically balanced and most of their input to output ratios are 0.7-1.5.

Key words: chlorimuron-ethyl, urea, microbial biomass carbon, microbial biomass nitrogen, inorganic nitrogen.