Abstract

The potential of biochar as a soil amendment in agricultural fields is a recently recognized and yet underutilized technology. The objective of this study was to investigate the mid/long-term effects of a single biochar application on soil physical properties, growth parameters and the yield of soybeans in a sandy clay loam. Biochar was added to a highly weathered tropical soil at rates of 40 tons ha-1 five years prior to this study (2017 to 2022). Soybeans were grown in the biochar-amended soils and the control in the 2021/2022 season. Biochar amendment significantly increased porosity, biological activity, improved soil structure type and grade, increased the initial and basic infiltration rates, and lowered the bulk density. Soybean growth characteristics, such as shoot length, weight, and diameter at the base; root weight, pod number, and grain yield, were significantly improved by biochar. The improved agronomic performance of the crop was attributed to improved rooting conditions, soil water-holding capacity, and nutrient use efficiency promoted by biochar amendment. Thus, biochar is a promising practical approach to improve soil agronomic properties, nutrient acquisition, and the yield of soybeans in a sustainable way on sandy clay loam soils.

Key words: Biochar, crop yield, soybeans, growth parameters, soil properties, Zambia.