Soil Amendment Potential of Sewage Sludge Biochar for Bok Choy under Tropical Greenhouse Conditions

Abstract

Sewage sludge management presents environmental challenges in Belize, while biochar production offers a pathway for stabilizing sludge and improving soil fertility. This study evaluated the effects of dried sewage sludge and sludge-derived biochar on soil properties and bok choy growth under greenhouse conditions using loam and clay loam soils. A factorial split-plot design compared five amendment treatments (control, dried sludge at 5% and 10%, and sludge biochar at 5% and 10%), replicated four times. Growth parameters and biomass were measured over six weeks, and soil physicochemical properties were assessed before and after treatment. Sludge-derived biochar, particularly at the 10% rate, produced the greatest improvements in plant growth and biomass, with clay loam showing stronger overall nutrient retention and biomass yield, while loam supported higher initial leaf proliferation. These results highlighted sludge-derived biochar as a sustainable soil amendment for improving crop performance and soil fertility in Belize.