Abstract: Asimulating test was made for examining the effect of soil water regime on the growth of rice and wheat. Apermeable soil colume with water percolation of 15mm diurnally in the growing season of rice and groundwater level being controlled at 70—80cm in the growing season of wheat was favourable for the growth of rice and wheat. Thus, the function of paddy soil ecosystem can be improved by regulating soil water regimes. Abudget calculation of nutrients showed that N, Pand Ca were surplus and K, Si, Mg, Fe and Mn were deficit in the soil colume. After 3 years of submerging, the differentiation of Fe and Mn in the soil profile had been observed, which was coincided with that under natural conditions.

Key words: Field winter wheat, Midday depression of photosy nthesis, Nonstomatic limitations