Effect of nitrogen management on grain yield of rice grown in a high-yielding environment under flooded and non-flooded conditions
Christopher G. Proud, S. Fukai, Brian W. Dunn, Tina Dunn, J. H. Mitchell
Abstract
With increased cost and scarcity of irrigation water, flooded rice growing system may need to be replaced with water-saving technologies which includes part or complete removal of flooding and to be replaced with non-flooded aerobic conditions. However, to maintain high grain yield equivalent to that achieved with flooded rice, nitrogen (N) management may need to be modified. Experiments were conducted in a high-yielding environment with total N applied up to 180 kg ha−1 and three application times to determine its effect on N uptake, grain yield and grain protein content of rice grown under aerobic (AR), delayed permanent water (DPW) and flooded (FD) conditions. Grain yield increased by 3.50–4.50 t ha−1 with total N application rate of 180 kg ha−1 in AR and 120 kg ha−1 in both DPW and FD. Maximum yield was about 10.5, 12.0 and 13.0 t ha−1 in AR, DPW and FD, respectively, and the difference was mostly reflected in the grain yield difference obtained under 0 N application. Apparent recovery of fertilised N and agronomic N use efficiency were similar between AR and FD, but DPW took up a higher proportion of N fertiliser applied before commencement of flooding and had slightly higher grain yield response to total N application up to 120 kg ha−1. It is concluded that the limitation for grain yield for rice grown in the AR condition was the crop's inability to take up N from the soil, rather than the inability to take up N fertiliser or to convert the N uptake to grain yield.