Author : San Hla Htwe

Summary : Traditional production of irrigated rice on puddled soil requires considerable irrigation was examined as a water-saving alternative in two cropping systems (dry season rice-mungbean and maize-wet season rice) in the Philippines. Rice yield at 24 to 27 sampling locations across 2.4 ha fields average 5.3 mg ha-1 (CV=16.4%) in the dry season and 5 Mg ha-1 (CV=21.8%) in the wt season. Rice yield as a fraction of theoretical climatic yield potential average 56% for the dry and 70% for the wet season. System productivity expressed as rice equivalent yield was 11.2 Mg ha-1 for maize-rcie and 6.4 Mg ha-1 for rice-mungbean. Rice yield was negatively correlated with electrical conductivity (ECa) to 0.5-m depth in the dry season. It was negatively correlated with penetration resistance in the top 0.15 m and ECa to 0.5-m depth in the wet season. Examination of the cropping systems in small replicated plots failed to capture spatial variations encountered in the large fields. Variations in soil physical properties associated with previous rice production on puddled soils might affect spatial variation in productivity of unpuddled rice-based systems.