The experimental field was located at the Cuu Long Rice
Research Institute (CLRRI; 10 080N: 105 350E), in the Omon district
of the Mekong delta of Vietnam. The soil (0e15 cm) has previously
been characterized in detail (Aaen et al., 2011). The particle size
distribution was 6.0% sand, 48.6% silt, and 45.4% clay and soil bulk
density was found to average 1.09 g cm3 for the 0e5 cm surface
layer. Soil organic C content was 1.35% (w/w), total N content was
0.15% (w/w), C:N ratio was 11.66 (mol:mol), and electrical
conductivity (EC) was 0.38 mS cm1. This alluvial soil type is well
suited for irrigated rice cultivation and represents the predominant
soil type used for rice cultivation in the Mekong Delta.