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Crop performance, nitrogen and water use in flooded and aerobic rice

Abstract Irrigated aerobic rice is a new system being developed for lowland areas with water shortage and for favorable upland areas with access to supplementary irrigation. It entails the cultivation of nutrient-responsive cultivars in nonsaturated soil with sufficient external inputs to reach yiel...

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Bibliographic Details
Published in:Plant and soil 2005, Vol.273, p.1-2
Main Authors: Belder, P, Bouman, B.A.M, Spiertz, J.H.J, Peng, S, Castañeda, A.R, Visperas, R.M
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Summary:Abstract Irrigated aerobic rice is a new system being developed for lowland areas with water shortage and for favorable upland areas with access to supplementary irrigation. It entails the cultivation of nutrient-responsive cultivars in nonsaturated soil with sufficient external inputs to reach yields of 70–80% of high-input flooded rice. To obtain insights into crop performance, water use, and N use of aerobic rice, a field experiment was conducted in the dry seasons of 2002 and 2003 in the Philippines. Cultivar Apo was grown under flooded and aerobic conditions at 0 and at 150 kg fertilizer N ha–1. The aerobic fields were flush irrigated when the soil water potential at 15-cm depth reached –30 kPa. A 15N isotope study was carried out in microplots within the 150-N plots to determine the fate of applied N. The yield under aerobic conditions with 150 kg N ha–1 was 6.3 t ha–1 in 2002 and 4.2 t ha–1 in 2003, and the irrigation water input was 778 mm in 2002 and 826 mm in 2003. Compared with flooded conditions, the yield was 15 and 39% lower, and the irrigation water use 36 and 41% lower in aerobic plots in 2002 and 2003, respectively. N content at 150 kg N ha–1 in leaves and total plant was nearly the same for aerobic and flooded conditions, indicating that crop growth under aerobic conditions was limited by water deficit and not by N deficit. Under aerobic conditions, average fertilizer N recovery was 22% in both the main field and the microplot, whereas under flooded conditions, it was 49% in the main field and 36% in the microplot. Under both flooded and aerobic conditions, the fraction of 15N that was determined in the soil after the growing season was 23%. Since nitrate contents in leachate water were negligible, we hypothesized that the N unaccounted for were gaseous losses. The N unaccounted for was higher under aerobic conditions than under flooded conditions. For aerobic rice, trials are suggested for optimizing dose and timing of N fertilizer. Also further improvements in water regime should be made to reduce crop water stress.
ISSN:0032-079X
1573-5036