Effects of continuous rice straw compost application on rice yield and soil properties in the Mekong Delta

Abstract

A field experiment was conducted to study the effects on yield and soil properties of the continuous application of rice straw compost to an alluvial soil in the Mekong Delta, Vietnam. Fourteen rice crops, two crops per year, were grown by direct seeding of the crop. There were seven treatments: F0C) (no fertilizer and compost), F0C+ (compost with no fertilizer), F20C+, F40C+, F60C+, F80C+ (20, 40, 60 and 80% of the fertilizer application rate with compost, respectively), F100C) (full strength fertilizer application as N:P 2 O 5 :K 2 O at 100:30:30 kg ha )1 in the dry season and 80:30:30 kg ha )1 in the wet season without compost). Compost prepared from the rice straw was applied at 6 Mg ha )1 (fresh weight) at the cultivation of each crop. The F0C+ treatment showed higher yield than the F0C) treatment by 0.68 Mg ha )1 on average in the wet season, but not in the dry season. The rice yield in F0C) declined at a rate of 0.163 Mg ha )1 year )1 in the wet season, but there was no decline in rice yield in F0C+. In treatments with compost, the yield reached its plateau at F40, suggesting that compost could replace part of the fertilizer. Although there were no significant differences in the total C concentrations in the soil among the treatments, even after 12 consecutive crops, soil penetration resistance appeared to be lower with compost than without compost. This long-term field trial showed that the continuous application of rice straw compost has some positive effects on rice yield as well as on soil physical properties.

Combined Effects of the Continual Application of Composted Rice Straw and Chemical Fertilizer on Rice Yield under a Double Rice Cropping System in the Mekong Delta, Vietnam

“…4) but were not correlated with the yield increase. These results are in accordance with those of previous studies 20 . The concentrations of K, Ca, Mn, Fe, Zn, and Cu did not differ significantly among treatments ( Table 3), suggesting that these elements may not be limiting factors for the rice yield.…”

“…The results of our present study contradict this conclusion. Watanabe et al 20 reported the significant effect of RSC application on soil physical properties. RSC application was shown to maintain soils in a softer state, i.e.…”

“…(1) F0C− (or control), 0:0: 20 . Rice straw was cut and removed from the field after harvest, while pest management practices followed the standard CLRRI practices.…”

“…Long-term studies on the effects of rice straw compost application were initiated during the 2000 wet season 20 . The rice crop was cultivated twice per year, during the wet and dry seasons.…”

“…In the present study, we investigated the long-term effects of the continuous application of rice straw compost on the overall soil fertility status of a Mekong Delta alluvial soil 20,21 . We also compared annual rice yield trends between plots fertilized with chemical fertilizer alone and those fertilized with a combination of rice straw compost (RSC) and chemical fertilizer.…”