Production of Tridax precumbens Biochar Based Organic Fertilizer and Effect on Growth and Weed Colonization of Amaranthus caudatus

Creating environmentally beneficial organic fertilizer using biochar generated from Afzelia Africana wastes (branches trimmings) and digestate of Tridax precumbens (T. precumbens) to reverse arable lands degradation by synthetic fertilizers is a novel approach. This work focused on production and application of T. precumbens biochar-based organic fertilizer (TBBOF) on growth and weed colonization of Amaranthus caudatus. T. precumbens digestate was produced via submerged state bioconversion for 15 days at room temperature and Afzelia africana waste biochar was produced using pit type Kontiki technology. T. precumbens digestate and pulverized biochar were homogenized to produce the fertilizer. The pH of T. precumbens digestate was 6.81 with 80% germination index. Gram-positive bacteria in digestate increased to 6.88 LogCFU/mL at day 15 while gram-negative bacteria reached 1.71 LogCFU/mL. Maximum total viable count was 1.41 LogCFU/mL. 40%v/v inclusion of TBBOF significantly (p<0.05) increased plant girth, height, number of leaves and leaf area of Amaranthus caudatus between week 2 and 4 after sowing in field experimentation under completely randomized block design (RCBD). Application of 60% TBBOF suppressed more weeds. Conclusively, T. precumbens digestate contained diverse bacterial population while 40%v/v inclusion of TBBOF offered most profound effects on growth of Amaranthus caudatus than NPK. 60% v/v TBBOF significantly reduced weed. The organic fertilizer showed promising capability to support crop growth; though further study is required to identify mechanism of nutrient release and weed suppression.