Pot experiments were conducted in a greenhouse to study nutrition of rice (Oryza sativa L., cv. Nato) under flooding and upland conditions. Yields of rice grown in one experiment on Mountview silt loam increased rectilinearly with 0-, 400-, and 800-mg rates of N/pot (5 kg of soil). Concentrations of N in grain + straw at maturity were uniformly low. Yields with the various water regimes were in the order: no flooding < flooding after 10 weeks < flooding after 6 weeks < flooding after 3 weeks. Multiple rates of N from 250 to 2,000 mg/pot and P from 0 to 1,000 mg/pot (6.25 kg of soil) were applied for Nato rice grown on Mountview silt loam and Sango silty clay loam in a second experiment. Marked yield responses to N and P were obtained. Yields of straw and of grain + straw, N uptake, and N recovery were higher on nonflooded than on flooded soils. Grain yields, however, were slightly higher with flooding.
Uptake of N, P, Ca, Mg, Mn, and Zn increased with yield response to N and P, while K uptake decreased on the Mountview soil. Concentrations of N and P increased with applied N and P, respectively, while concentrations of other nutrients were diluted in most situations with yield response to N or P on both flooded and nonflooded soils.
These results indicate that with adequate applied nutrients, especially N, yields of rice with adequate water but without flooding can equal or even exceed those under flooding.