Farmer-managed French bean biochar trials in Rwanda: Effects on yield and soil nutrients

Abstract

In pursuing sustainable and environmentally friendly agricultural practices, using biochar derived from Top-Lit Up-Draft (TLUD) stoves in  agriculture has gained significant interest. Biochar (B) from TLUD was applied in furrows in 60 kitchen gardens of French beans  (Phaseolus vulgaris) using randomized paired design at a rate of 3 tons/ha in Rwanda’s Huye and Bugesera districts. Data on yield and  the soil properties were collected and analyzed using One-way analysis of variance (ANOVA) within a generalized model in R, followed by  Tukey’s test (P<0.05). The results showed a consistently positive response in French bean yield following a onetime biochar application in  both sites. In Bugesera, yields were 21.6 t/ha in season 1, 24.1, and 28.8 t/ha in season 3. In Huye, yields were slightly lower with 21.6t/ha, 24.3t/ha and 27.3 t/ha for season 1,2 and 3 respectively. The soil's chemical properties in treated and control plots ranged as follows: pH  4.9–7.4, available phosphorus 1.3–8.3 ppm, total nitrogen 0.1–0.4%, calcium 3.3–7.6 cmol+/kg, magnesium 0.04–1.7 cmol+/kg, potassium  0.02–0.7 cmol+/kg, and cation exchange capacity 7.3–13.3 cmol+/kg. Biochar application significantly increased soil porosity by 15.2% and  plant-available water by 24.1%, while reducing soil bulk density by 15.3% compared to the control. It is evident from the results that  biochar improves soil fertility, boosts french bean yield, and support sustainable farming and energy practices. This technology promotes  the use of biochar in soil management and suggests that adopting TLUD stoves can enhance energy sustainability by reducing  fuel consumption.