Maize response to intermittent submergence,straw mulching and supplemental N-fertilization in subtropical region

Summary A 2-year field study was undertaken on a sandy loam in a tropical monsoon region to determine the growth and yield response of maize (Zea mays L.) to 10–11 day intermittent submergence at two growth stagesviz., 20 (stage 1) and 40 (stage 2) days after planting, in combination with two rates of rice straw mulch (0 and 6 t/ha) and three levels (0, 30 and 60 kg/ha) of soil-applied supplemental nitrogen. Intermittent submergence at both growth stages caused a severe oxygen stress in the root-zone. Compared with no-flooding, stage-1 flooding without additional N reduced the grain yield by 51 and 69%, stover yield by 16 and 45% and grain: stover ratio by 41 and 47% in the first and second year, respectively. Similar were the submergence effects on N, P, K and Zn concentrations in leaves, ears per plant and grain weight per ear. Relatively more adverse effects of stage-1 flooding in the second than the first year followed from the hotter soil and atmospheric environments in the former season. The stage-2 flooding produced practically no ill effects on growth and yield of the crop. Soil application of 60 kg N/ha after termination of stage-1 flooding recovered the grain yield by 77% in the first year and 65% in the second year. Additional nitrogen also benefited the growth and yield characters. The interactive effects of straw mulching with flooding were not distinct. Senior Scientist (Irrigation), formerly graduate student and Assistant Soil Physicsts, respectively.