Enhancing Soil Properties and Okra (Abelmoschus esculentus L.) Growth through Biochar and Ash Derived from Indigenous Plants Maerua crassifolia and Saccharum kajkaiense

Abstract

Locally produced soil amendments can play a vital role in sustainable agriculture, enhancing soil quality and crop plant growth. This study investigated the impact of locally sourced biochar (BC) and ash, obtained from Maerua crassifolia Forssk. (wood), and Saccharum kajkaiense, Melderis (grass) on soil properties and okra (Abelmoschus esculentus) biomass. We assessed different application rates (10% and 20%), either separately or combined with the potting soil/peat (Biomix). Biomix application reduced soil pH (7.9),and increased soil organic mater (OM) (51.9%), NO3-1 (17.5%) levels, water holding capacity (WHC) (22.9%), and dry biomass (37.7%) of okra compared no Biomix application. Among BC and ash amendments, grass ash excelled, increasing okra biomass by 132.7%, followed by wood BC and grass BC. However, wood ash had a slight negative effect on okra dry weight and also increased the soil EC (6.12 dS m-1). Wood ash had higher K levels (758 mg kg-1) but lower Na (159 mg kg-1) compared to control (51 mg kg-1 K and 235 mg kg-1 Na). Both BC amendments raised soil organic matter (OM) by 7.63-8.69%, while wood and grass ash slightly increased soil P (57.7-64.6 mg kg-1). However, wood and grass BC reduced soil P to 44 mg kg-1. Grass ash raised NO3 levels (25.5%) compared to the control. The interaction of Biomix with wood and grass amendments decreased soil EC, increased soil OM, NO3 level and plant dry weight of okra. Wood and grass BC (20%) with Biomix enhanced the soil OM by 11%. The combination of 10% grass ash and Biomix resulted in the highest NO3 levels at 170 mg kg-1. Furthermore, the combination of Biomix and 10% grass ash produced the most significant increase (204.3%) in plant dry weight compared to the control. In conclusion, locally sourced biochar and ash amendments, particularly grass ash in combination with potting soil/peat (Biomix), demonstrated significant potential to enhance soil quality and crop biomass, offering valuable insights for sustainable agricultural practices.