Soil loss due to harvesting of peanut and cassava under traditional farming systems: Cost implications of soil nutrient loss

Abstract

Soil loss due to crop harvest contributes to land degradation, and knowledge of this challenge can guide the choice of crops for sustainable agriculture. Nigeria is the largest producer of cassava (Manihot esculenta Crantz) and the third largest producer of peanut (Arachis hypogaea Linn) in the world. Due to limited information on soil loss during peanut and cassava harvests worldwide, and cost of nutrient loss, a two-year field experiment was conducted to compare soil loss due to harvesting of peanut and cassava and to estimate cost of nutrient loss due to crop harvest under traditional agriculture. Peanut pod yields of 2.39 and 2.08 t ha^–1harvest^–1 removed 0.62 and 0.58 t ha^–1 harvest^–1 during peanut harvest, respectively, for years 1 and 2. Similarly, cassava yields of 22.71 and 21.40 t ha^–1 harvest^–1 removed 1.11 and 0.91 t ha^–1harvest^–1 during cassava harvest, respectively, for years 1 and 2. Crop yields strongly correlated with soil loss due to peanut harvest (R²= 0.36; p < 0.001) and soil loss due to cassava harvest (R² = 0.23; p < 0.01). Significantly higher soil loss due to cassava harvest compared to peanut harvest can be ascribed to higher cassava yield. Also, soil nutrient loss due to crop harvest was significantly (p < 0.001) higher for cassava compared with peanut by 27.6% phosphorus (P) and 73.7% potassium (K) for the first year and 39.2% P and 79.1% K for the second year. Fertilizer equivalent cost of P and K losses due to cassava harvest for the two years was higher than that of peanut by US$29 ha^–1. The study indicated that the intensity of nutrient loss by harvesting is largely dependent on the crop type, and harvesting of cassava can deplete soil nutrients faster than that of peanut under traditional agriculture. Sequential planting of cassava (deep rooted crop) followed by peanut (shallow rooted crop) as a crop rotation management practice is recommended to mitigate soil loss due to continuous harvesting of cassava, and harvesting with thorough shaking technique is also suggested to reduce nutrient loss potential of crop harvesting.