Soil and Postharvest Responses of Tomato to Biochar and Calcium Amendments

Abstract

The potential of cow bone biochar combined with calcium fertilizers to enhance tomato shelf life remains insufficiently explored. This study evaluated the effects of biochar and calcium sources on soil chemical properties, growth, yield, quality, and shelf life of tomato in a screen house experiment. Treatments consisted of five biochar rates (0, 10, 20, 30, and 40 t ha⁻¹) and four calcium sources (control, calcium sulphate, calcium nitrate, and poultry manure) arranged in a 5 × 4 factorial using a Completely Randomized Design with three replications. Poultry manure produced the highest fruit yield, increasing production by 22% over mineral calcium sources and 382.5% over the control. Increasing biochar rates improved nutrient availability, with 40 t ha⁻¹ enhancing yield by 294% compared with the control, likely due to improved soil fertility, nutrient retention, and higher cation exchange capacity. Calcium sulphate was most effective in reducing fruit weight loss and extending shelf life, increasing storage duration by up to 69% relative to the control. This improvement is attributed to enhanced calcium uptake, which strengthens cell walls and reduces membrane degradation during storage. Significant interaction effects were observed: 30 t ha⁻¹ biochar combined with calcium sulphate extended shelf life by 123% compared with the control. This synergy suggests that biochar enhances calcium retention and availability, thereby improving fruit structural stability. The combined application of 30 t ha⁻¹ biochar and calcium sulphate is recommended to improve tomato yield and postharvest quality, although field validation is necessary for large-scale adoption.