Assessing the synergistic impacts of poultry manure and biochar on nutrient-depleted sand and sandy loam soil properties and sweet potato growth and yield

Summary Poultry manure (PM) has been shown to boost crop productivity. However, little is known about its favorable interactions with wood biochar (B) on sweet potato ( Ipomoea batatas L.) growth and yield, and soil qualities. Hence, a 2-year field trial was conducted in the southwest Nigeria at two locations (Owo – site A and Obasooto – site B) to co-apply PM and wood B as soil amendments to boost sweet potato productivity and soil quality. The experiment consisted of a 3 × 4 factorial layout with three replications. PM and B significantly reduced soil bulk density and improved porosity and moisture content with their rate of application when compared to the control. As PM and B applications increased from 0 to 10.0 t ha −1 and 0 to 30.0 t ha −1 , respectively, soil chemical properties and sweet potato growth and tuber yield increased. Co-application of 10.0 t ha −1 PM and 30.0 t ha −1 B increased tuber yield by 220% compared to treatments without PM or B. Significant synergistic interactions between PM and B were observed for all parameters. In comparison with other treatments, co-applying PM and B to sweet potato soils is a viable sustainable option for increasing sweet potato productivity and soil sustainability.