Biochar and biodigester effluent increase the yield of Yardlong bean (Vigna unguiculata) and improve soil properties

Abstract

Biochar application to improve soils fertility and crop yield has been increasingly concerned worldwide to combat soils degradation while mitigating the greenhouse gases. However, the effects have not been determined in a wider range of crops especially vegetables. This experiment was carried out at the Integrated Farming Demonstration Centre, Champasack University, Lao PDR to determine the effects of biochar and biodigester effluent on soil properties and yield of Yardlong bean. Six treatments were arranged in a randomized complete block design (RCBD) as a 2*3 factorial with 4 replications. The factors were: 1) biochar application rate at 0 or 40t/ha; and 2) level of biodigester effluent: 0, 50 or 100 kg N/ha. Biochar was obtained from rice husk in the Top Lid Updraft (TLUD) gasifier stove, and effluent was collected from a "plug-flow" tubular polyethylene biodigester. Measurement of soil physical properties, yield component, and yield of Yardlong bean were performed.

Application of biochar and effluent increased the yield of Yardlong bean by 50% compared to the control treatment. Empty pods of the bean were reduced 2 fold when biochar was applied at 40t/ha. Soil pH was improved due to biochar amendment. Water holding capacity of the soil was significantly increased when biochar was applied at all levels of effluent which could be a good sign for water efficiency usage.