Reducing methane and nitrous oxide emissions from rainfed paddy fields using corn cob-derived biochar at Central Java, Indonesia

Rainfed paddy fields constitute approximately one-third of Indonesia’s total rice (Oryza sativa L.) field area, including those distributed in Central Java Province. Rainfed lowlands are susceptible to the effects of climate change. Furthermore, there are several challenges in managing rainfed paddy fields, such as low crop productivity, poor soil fertility, and drought stress. Utilizing agricultural waste as biochar is expected to enhance soil quality, increase crop productivity and reduce greenhouse gas emissions responsible for global warming. The research aimed to determine the emissions of methane (CH4) and nitrous oxide (N2O) from rainfed paddy fields by using the corncob (Zea mays L.) biochar as urea coating (BCU), and biochar combined with compost. The research was conducted in rainfed paddy fields using a randomized block design with three treatments and four replicates. Plant growth, grain yield, CH4 flux, and N2O flux were among the parameters measured. The result showed that biochar utilization, both as a urea coating (BCU) and in combination with compost, significantly improved plant growth, increased grain yields of ‘Ciherang’ rice, and reduced more CH4 and N2O emissions in rainfed paddy fields. Grain yield increased by 29.2% with biochar-coated urea (BCU), and 11.9% with the biochar-compost combination. Furthermore, the application of biochar-compost and BCU reduced daily CH4 flux by 93.2% and 97.7%, respectively. Compared to conventional farmer practices, biochar-compost resulted in a greater reduction in N2O flux than BCU. Thus, utilizing agricultural waste biochar in lowland rice cultivation can increase productivity while mitigating climate change impacts.