Effects of biochar-urine amendment on soil loss associated with Sweet Potato (Ipomoea batatas L.) harvesting

Biochar with urine has potential to enhance crop productivity and minimize soil loss during harvesting. Hence, a field study was conducted on a sandy loam Alfisol at the Teaching and Research Farm, University of Ibadan, Ibadan, Nigeria, to evaluate the effects of biochar-urine application on soil loss due to harvesting of sweet potato. The experiment was laid out in a randomized complete block design with six treatments replicated three times. The six treatments comprised three sole applications (biochar at 3 t ha⁻¹, cow urine at 3,000 liters ha⁻¹, and NPK 15:15:15 at 400 kg ha⁻¹) and two combined applications (biochar at 1.5 t ha⁻¹ with NPK at 200 kg ha⁻¹ and biochar at 1.5 t ha⁻¹ with cow urine at 1500 l ha⁻¹) and an unamended control (no additive). The response variables measured were aboveground biomass, crop yield, and soil loss due to crop harvesting (SLCH). Soil loss was determined by collecting, air-drying, and weighing the soil adhering to harvested tubers, and SLCH was computed from these measurements. Nutrient loss (C, N, P, K, Ca, Mg, Na) was quantified. Biochar-urine application gave an increased yield by 20.5% and reduced Soil Loss due to Crop Harvesting (SLCH) by 21.6% compared to biochar-NPK. The use of biochar amended with cow urine may be a promising approach to improving crop yield while minimizing soil loss. Also, there was a positive correlation between soil loss and soil nutrient loss, showing the deleterious consequences of soil loss due to crop harvesting on soil productivity.