Malaysian Society of Soil Science

Abstract
Intensive farming is expanding rapidly, making organic fertilizer development vital to achieve sustainable agriculture. Thus, the purpose of this study is to understand the potential of decaying plants and industrial sewage sludge as organic soil amendments. This study was conducted from December 2019 to May 2021 in Ho Chi Minh City. Decaying plants and sewage sludge from wastewater treatment enterprises were collected. Manure and probiotics were also added according to the semi-fermentation method to develop different composting formulas. The quality of fertilizer was evaluated based on national standards. The last step was to observe the compost applications potential in improving acidic soil moisture and soil pH. The study found that the composts containing 70% plant waste + 20% cow manure + 10% dried sludge + microbial (0.25 liters/1m³) met the nutrient criteria of the Vietnamese Government on fertilizer management as follows: pH 6.7, total organic matter 31.08%; total N 2.37%; 5.67% P₂O₅, 8.97% K₂O; humic acid 2.59%; fulvic acid 1.24%; and C:N ratio 11.03. After applying the compost fertilizer (10,000 kg/ha), a significant improvement in acidic sulfate soil pH and moistureholding capacity was recorded compared to the conventional methods of farming.