Influence of Graded Doses of Coffee Biochar on the Growth of Arabica Coffee Seedling

Abstract

Biochar is a porous and carbon-rich product obtained from the thermal disintegration of solid agricultural waste biomasses in an oxygen-limited atmosphere. In recent years, the subject of biochar has increasingly become popular worldwide due to its potential to improve soil fertility and several studies have demonstrated the benefits of soil application of biochar in various crops. However, reports on the application of biochar in coffee farming are rather very limited. Thus, a study was undertaken to assess the influence of biochar application on the growth of arabica coffee seedlings, specifically in terms of shoot length, root length, fresh shoot biomass, fresh root biomass, dry shoot biomass, and dry root biomass. In the present study, biochar obtained from coffee cherry husk (a waste biomass obtained while dehusking cherry coffee) was used for the nursery trial. The biochar produced using an electric biomass pyrolyzer at 500°C for one hour was incorporated into the nursery potting medium (NPM). The experiment consisted of six treatments: T0 (standard NPM-control), T1 (standard NPM+1% biochar), T2 (standard NPM+2% biochar), T3 (standard NPM+3% biochar), T4 (standard NPM+4% biochar) and T5 (standard NPM+5% biochar). The treatments were imposed in a completely randomized design with five replications per treatment and fifty seedlings per replication. The results indicated that the growth of arabica coffee seedlings was found to be superior in T3 (potting medium with 3% biochar) and T4 (potting medium with 4% biochar) as compared to other treatments (T0, T1, T2, T5). Further, the availability of nutrients (nitrogen, phosphorous and potassium) was found to be higher in biochar-treated soil when compared to soil from the control treatment (T0). These findings suggest that biochar at the rate of 3% to 4% improves the growth of arabica coffee seedlings by modifying the physicochemical properties of soil, as evidenced by the changes in the pH, electrical conductivity, organic carbon content and nutrient status.