Soil properties, sweet potato growth and yield under biochar, poultry manure and their combination in two degraded Alfisols of humid tropics

Abstract

Information on the impact of biochar and poultry manure on soil characteristics and sweet potato productivity in the humid tropics is lacking. Hence, field experiments were conducted at two locations during the 2019 and 2020 cropping seasons to assess the effects of biochar (B), poultry manure (PM), and their mixture on soil physical and chemical properties, growth and tuber yield of sweet potato (Ipomoea batatas L.) Each year, the experiment consisted of 4 × 3 factorial combinations of biochar (0, 10.0, 20.0 and 30.0 t ha−1) and poultry manure (0, 5.0 and 10.0 t ha−1). The findings revealed that using B and PM alone, as well as in combination, improved soil physical properties, increased soil chemical qualities, and sweet potato performance. Significant interactions of B and PM (B × PM) were observed on soil characteristics and sweet potato variables that were measured in both years, emphasizing B's potential in enhancing PM use efficiency. Pooled over two years, application of the highest dosage of B at 30.0 t ha−1 and PM at 10.0 t ha−1 (B30+PM10) significantly increased tuber yield of sweet potato by 108, 147, 196, 89, 124 and 220%, compared with sole B at 30.0 t ha−1 (B30+PM0), sole B at 20.0 t ha−1 (B20+PM0), sole B at 10.0 t ha−1 (B10+PM0), sole PM at 10.0 t ha−1 (B0+PM10), sole PM at 5.0 t ha−1 (B0+PM5) and the control (B0+PM0), respectively. The findings indicate that B and PM have the ability to improve soil quality and sweet potato productivity.