Effects of biochar and fertilizer on yield and actual seasonal crop evapotranspiration of rainfed watermelon in Ishiagu, Ebonyi State, Nigeria

Abstract

Soil infertility, declining yield, and decreasing water resources are constraints to agricultural productivity. This study investigated the effect of biochar and fertilizer on the actual seasonal crop evapotranspiration of rainfed watermelon in Ishiagu, Ebonyi State, Nigeria. Four treatments were used: control (T0), fertilizer only (T1), biochar only (T2), and biochar + fertilizer (T3). The treatments were each replicated three times in a randomized complete block design. Data was subjected to analysis of variance. Significant means were separated using Tukey Honestly Significant Difference at p<0.05. The amount of total seasonal rainfall during the experiment was 686.79 mm. The result showed that the actual seasonal crop evapotranspiration (ET) was estimated using the soil–water balance method and ranged from 602.95 to 615.83 mm across treatments. The ET was highest in T1 (615.83 mm). T0 had the lowest ET (602.95 mm), while T3 had a value of 603.92 mm, and T2 had 604.62 mm, respectively. Watermelon fruit yield differed significantly among treatments (p < 0.001); T3 produced significantly higher yield than all other treatments (p < 0.05). T3, despite having a lower ET value (603.92 mm) than that of T1 (615.83 mm), produced the highest yield, while its calculated actual seasonal crop evapotranspiration was numerically, slightly, lower than that of T1. The study concluded that the integration of biochar with fertilizer is a viable approach for improving both watermelon productivity and crop water productivity under rainfed conditions.