Examining the Effect of Combined Biochar and Lime Rates on Selected Soil Physicochemical Properties of Acid Soils in Gimbi District, Western Ethiopia

Abstract

The physicochemical properties of Western Ethiopian soils were negatively threatened with continuous cultivation crop lands. Soil amendments with biochar and lime facilitate and improve soil physicochemical properties directly and indirectly and enhance crop productivity. A field experiment was conducted in Gimbi District, Western Ethiopia, to examine the effects of combined coffee husk biochar (CHB) and soil test value-based lime (STV) rate application on physicochemical properties of acid soils. The trial included eight treatments, including control, 100% STV, 10 ton of CHB, and CHB + STV rates at 10 ton + 75%, 10 ton + 50%, 7.5 ton + 75%, 7.5 ton + 50%, and 5 ton + 75% ha−1on two farm fields. The fields were laid out in RCBD with three replications. The treatments had substantial effects on $P<0.05$) on the soil’s physicochemical characteristics. The application of biochar and lime in Farms-1 and 2 reduced soil BD from 1.21 and 1.41 g·cm−3 to 1.15 and 1.12 to 0.90 and 0.97 g·cm−3, respectively. The soil pH level was increased from 5.10 to a range of 5.58 to 6.11 in Farm-1, and in Farm-2, from 4.64 to a range of 4.64 to 6.22 levels. The application of 10 ton of CHB + 75% of STV in Farms-1 and 2 resulted in the highest SOC of 7.44% and 7.68%, respectively. The application of 10 ton of CHB + 75% of STV in Farms-1 and 2 resulted in 4.86 mg·kg−1 and 6.96 mg·kg−1 available P, respectively. Available P was positively correlated with pH (0.62), SOC (0.63), and CEC (0.66). Exchangeable acidity was decreased from 4.64 cmol(+)kg−1 to a range from 3.19 to 0.98 cmol(+)kg−1 in Farm-1 and from 5.00 cmol(+)kg−1 to a range from 3.38 to 1.10 cmol(+)kg−1 in Farm-2. Therefore, amending the strongly acidic to very strongly acidic soil with a combined CHB (7.5 to 10 ton ha−1) and STV (50 to 75% ha−1) rates had improved the soil physicochemical properties of agricultural lands. To make a firm conclusion, research on soil analysis after crop harvest and economic benefit is required.