Analysis and simulation of water and crop management effects on the field performance of aerobic rice (Oryza sativa L.) in Los Baños, Laguna, Philippines
2009
Acosta, J.E.
Aerobic rice is a new production system targeted at water-limited environments which rice is grown under non-flooded, non-puddled, and non-saturated soil condition. Since aerobic rice is relatively a new technology, good water and nitrogen management schemes were necessary. A combined field experiment and modeling approach was used to evaluate and simulate water and nitrogen effects on yield and growth of aerobic rice cultivar Apo. In the dry-season (DS) of 2004 and 2005, a water x nitrogen (N) experiment was conducted at the IRRI [International Rice Research Institute] experimental farm in Los Baños, Laguna, and ORYZA2000 was used to support the interpretation and experimental results and to perform sensitivity analysis. The experiments were set up in split-plot design on a light clay soil with three water regimes (irrigation twice per week, once per week, and once every two weeks with modifications), and 5 N levels (0 to 200 kg/ha 1). On average, yield was 1.1 tons/ha and 0.6 tons/ha in DS 2004 and 2005, respectively. Despite low yields caused by micronutrient imbalances and nematodes, growth and yield were significantly affected by water regimes and nitrogen application rates. Grain yield was significantly affected by the interaction of water and nitrogen in DS 2004. Leaf area index (LAI), biomass and yield components responded strongly to N. Aerobic rice reduced irrigation water input, increased water productivity and contributed a net seasonal water input to ground water recharge. Average simulated grain yield was 5.3 tons/ha with yield generally increasing at higher water and nitrogen levels with water productivity ranging from 150 to 900g grain/cu m water. This study demonstrated that there is a potential for aerobic rice during dry season. However, the risk of occurrence of micronutrient imbalances and underground pests should be assessed before targeting an area for aerobic rice dissemination.
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