Theeba Manickam
Abstract
Tropical soils, such as Malaysia’s haplic Acrisols, are often challenged by acidity, low nutrient availability and low productivity. This study investigated the potential of co-composting rice husk biochar (RHBC), a byproduct from local rice mills, with poultry manure to improve these soil conditions. Four soil amendments were evaluated: (1) RHBC alone, (2) composted poultry manure (Co), (3) co-composted poultry manure with RHBC at 5% (Co-BC5) and (4) co-composted poultry manure with RHBC at 10% (Co-BC10), with an untreated control. A 30-day soil incubation experiment demonstrated significant improvements in soil properties, especially with Co-BC10. Soil pH increased by up to 0.8 units, approaching the optimal range for nutrient availability. Total carbon content rose by 26%, with Co-BC10 contributing the most due to the stabilisation of organic carbon. Nutrient availability also improved, with total nitrogen rising by up to 13%, available phosphorus by 26%, and exchangeable potassium by 18%. Among the treatments, Co-BC10 consistently outperformed the others in enhancing soil properties. These results emphasise the potential of Co-BC10 as an effective amendment for tropical soils, offering promising implications for sustainable agriculture. Further research into long-term field applications and higher dosage rates could help optimise its benefits for broader agricultural use.
Keywords: biochar, compost, poultry manure, haplic Acrisols and cation exchange capacity