Effect of Season of Planting and Fertilizer Application on Cassava Production and Profitability in Upland Cropping Systems in the Southeast Cambodia

The shift towards continuous mono-cropping of cassava and maize has led to soil degradation, loss of soil fertility, declining yield and profit for smallholder farmers in upland cropping areas of Cambodia. This requires the development of technologies for sustainable agricultural production in the uplands of Prey Veng and Svay Rieng provinces in Cambodia. However, studies regarding technology transfer have been published by various existing research, and none of the research has yet been conducted in Southeast Cambodia. This paper has investigated the effect of varying planting dates and fertilizer applications on cassava production and profit in South-Eastern Cambodia. Field experiments were carried out to investigate the effect of season of planting and fertilizer application on cassava fresh tuber yield and profitability in Prey Veng and Svay Rieng provinces. The experiment was arranged in a 2x2x2x4 Factorial Randomized Design Experiment with factor Province (Prey Veng, Svay Rieng); Season (early wet season: May-December, late wet season: August-April); and fertilizer (nil, plus). Measurements were taken for crop establishment (%) and yield of wet tuber (ton.ha-1). The profitability of experimental treatments was determined using gross margin analysis. The experimental result showed that the growth and production of cassava in Southeast Cambodia are influenced by planting area, planting time, and fertilization. Cultivating cassava in Svay Rieng Province results in higher growth, production, and profits than in Prey Veng Province. Cultivating cassava in the early wet season results in higher growth, production, and gross margins compared to the late wet season. Cassava is very responsive to fertilization but the application of fertilizer has not provided economic benefits on land conditions with low productivity. To increase cassava productivity and maintain soil fertility in South-Eastern Cambodia, it is necessary to select an appropriate planting area, plant during the early wet season and apply fertilization based on soil analysis. The application of intercropping and crop rotation is necessary in order to obtain fertile soil for optimal cassava growth and production.