Soil Fertility Management in Rainfed Lowland Rice Eco-systems

Abstract

Rice (Oryza Sativa L.) is a staple food of the Cambodian population and accounts for 68-70 percent of daily calorie intake. Rainfed lowland rice ecosystems are often hampered by drought, submergence and soil problems (Acid Sulphate) that are associated with low productivity and with a high incidence of poverty. A study was conducted to identify the best practices in soil fertility management and conservation on sandy soil for improving rice yield and cost effectiveness of rainfed lowland rice production systems in order to contribute to the improvement of food security and income generation of rural farmers. Three experiments were conducted in rainfed lowland rice agro-ecosystems in Champei commune, Bati district of Takeo province from the middle of 2006 to the middle of 2009: (i) assessment of agro-ecosystem analysis and rice agro-ecosystems, (ii) study on interaction and cost-effectiveness of NPK fertilizers and compost on rice yield in sandy soil in rainfed lowland production systems and (iii) on-farm adaptive research on interaction of NPK fertilizers and compost in sandy soil of rainfed lowland rice ecosystems. The results clearly indicated that the factors and parameters impacting on rice productivity and yield are poor soil fertility (sandy loam soil) and poor soil fertility management. Two options of best practices were identified for improving soil fertility management and rice yield. Firstly, for farmers raising a limited number of cattle (1-2 cattle) and limited access to compost fertilizers should use N₂₅P₁₃K₁₅ or Urea at 44 kg, DAP 25 kg and KCl 25 kg plus 5 tones of compost per hectare. Secondly, for farmers raising more cattle and producing large amounts of compost fertilizer recommendations are the same with 10 tones of compost per hectare.