Sustainable Agricultural Practices: Enhancing Rice Yield and Reducing Methane Emissions in Degraded Soils via Soil Amendments and Silicon Application

The present study addresses Ghana's heavy dependence on rice imports, which currently make up over 40% of the nation's domestic consumption with declining soil fertility. The use of organic and chemical fertilizers to improve soil fertility has had an unintended consequence like the production of methane (CH4) gas. This study investigates the potential of biochar, a promising solution for reducing emissions and enhancing crop yields when combined with silicon (Si). This research assessed the effect of these soil amendments on rice yield and methane emissions within degraded rice fields. The main treatments were recommended fertilizer dose (RDF), a biochar compost (BIOCOM) application, and a combination of 50% RDF with 50% BIOCOM. Within these treatments, Si was introduced at varying levels: 0, 100, and 200 kg Si ha-1. The results indicate that the application of RDF resulted in significant improvements in rice growth, Si uptake, phosphorus (P) uptake, and ultimately, grain yield. RDF produced remarkable yield increments, surpassing BIOCOM by 59.7% in 2020 and 56.6% in 2021. Additionally, the introduction of 100 kg Si ha-1 led to an average 15.6% increase in grain yield across both growing seasons and displayed a positive correlation with P uptake. BIOCOM and its blend with NPK improved residual P and K contents. BIOCOM reduced CH4 emissions by 46% in 2020 and 44% in 2021 when compared to RDF. This study does not only hold valuable implications for sustainable agricultural practices but also make a substantial contribution to addressing key concerns, including food security, soil fertility preservation, and the reduction of CH4 gas emissions in rice production.