FIELD WATER MANAGEMENT AND N-RATES TO SAVE WATER AND CONTROL IRON TOXICITY IN LOWLAND RICE

Field trial was conducted in 2009 and 2010 to evaluate water and nitrogen management on concentration of iron as it affects yield of lowland rice in the National Cereals Research Institute (NCRI) research fields in Bida, Nigeria. The results obtained show that there were significant differences in plant height, panicle numbers, straw and grain yield when compared with the control (farmers practice). There were no significant differences in grain yield between treatments 3 and 4 with values of 3.05 and 3.02 t ha-1 under flooding till harvest and the application of 80 and 100 kg N ha-1. Yields generally increased with increasing levels of nitrogen and declined from 80 kg ha-1. Nitrogen use efficiency decreased with increasing levels of nitrogen rates and was 15 to 25 kg kg-1 across the treatments. There were also significant differences in plant tissue iron content. Iron concentration was higher in the control than treatments with higher levels of nitrogen as shown by iron concentration in the plant tissue. Irrigation water was applied at soil moisture tension of -30 KPa. The total water applied was 1441 mm including rainfall for the treatment that had flooding till harvest. The treatment that was drained three times at determinate intervals saved 144 mm and water use efficiency was 2.26 to 5.09 kg mm-1. Appropriate water and nitrogen management could reduce the intensity of iron in rice to enhance sustainable yield increases of paddy rice and save water in the lowland soils of Bida area.