MODELLING TOMATO YIELD AND CROP WATER REQUIREMENTS UNDER BIOCHAR AMENDMENT IN A TROPICAL ENVIRONMENT

Abstract

The purpose of this study was to quantify water use and yield of tomato crops grown on biochar-amended soils in tropical conditions of Ibadan, Nigeria. Field experiments incorporated FAO AquaCrop and CROPWAT alongside five levels of biochar application (0, 5, 10, 15 and 20 t ha⁻¹). Reference evapotranspiration was estimated using the Penman Monteith FAO method. Biochar influenced soil structure. Increasing biochar application rate to 20 t ha⁻¹ increased soil moisture by 38%, reduced bulk density by 13%, and increased soil's available water capacity by 42% relative to the control. The seasonal need for irrigation was reduced by 11.6%, and deep percolation was reduced from 37 to 14 mm. The application of biochar increased the yield of tomatoes to 40.2 t ha⁻¹, a 62% yield increase from the control. Water use efficiency was 7.8 kg m⁻³; a 53% increase was also observed from the control. The observed yield from the simulations of AquaCrop was in agreement. Positive correlations were observed between biochar rate and soil moisture, yield, and water use efficiency. Biochar amendments along with crop water modelling can be a sustainability innovation to enhance tomato production and irrigation on tropical soils.