A field research experiment was conducted in the 2020/2021 rain season at St. Joseph Secondary School in Beitbridge to evaluate the effect of Biochar and trichoderma on forage sorghum yield in semi-arid regions of Southern Zimbabwe. The trial was a factorial experiment in a Randomised Complete Block Design (RCBD) and were replicated three times. Germination percentage, plant height, stem girth, leaf area as well as yield (Wet and dry mass) of forage sorghum were the parameters measured and the data was analysed using Genstat, (Analysis of Variance at P<0.05). The results showed that T. harzianum significantly improved germination percentage of forage sorghum by 3.92% at P<0.05, that is Control recorded 86.26% and 1gm/m2 recorded 90.18% and biochar levels did not improve germination of forage sorghum. T. harzianum did not show any increase in growth in relation to plant height, however, it promoted growth of stem girth from 2.096cm to 2.412cm (on week 3) and 6.07cm to 6.69cm (on week 7) at P<0.01 and P0<05 respectively. T. harzianum increase growth of leaf area by 34cm2 from 272.8cm2 (control) to 306.8cm2 (on week 5) at P<0.01. The interaction between biochar and T. harzianum also resulted in a significant growth on stem girth on the third week which recorded the highest stem girth of 2.749cm against 2.013cm from the control treatment at P<0.01 and at 7th week, stem girth increased by 2.22cm at P<0.05. Biochar also resulted in increase in growth of leaf area of forage sorghum at P<0.05 on week 5, (Control treatment recorded 268.2cm2 , 3tha-1 produced a leaf area of 292.2cm2 and 5ha-1 yielded 308.9cm2 ) and P<0.01 on week 7. The interaction between biochar and T. harzianum also showed a significant increase in growth of stem girth on the third week and seventh week at P<0.01 and P<0.05 respectively. Biochar increased the height of forage sorghum between biochar application rates, that is between control (No biochar) at 20.6cm and 3tha-1 levels (24.22cm) at P<0.01 at 2 weeks, P<0.01 at 5th week (No biochar-64.4cm, 3tha-1 - 72cm and 5tha-1 - 78.7cm) and P<0.01 at week 7. There was an increase in wet mass yield by 4.8tha-1 on 3tha-1 biochar and 9.8tha-1 on 5tha-1 biochar at P<0.01. Dry matter yield increased by 1.1tha-1 on 3tha-1 biochar and 3.06tha-1 on 5tha-1 biochar. Farmers are therefore recommended to make use of T. harzianum to enhance seed germination as well as make use of available forestry waste to make biochar such that they will improve forage sorghum yields as well as livestock productivity.

Keywords : Biochar, Trichoderma harzianum, forage sorghum.