Study of Organic Fertilizers and Rice Varieties on Rice Production and Methane Emissions in Nutrient-Poor Irrigated Rice Fields

The problem of rice farming in Indonesia is the increasing extent of nutrient-poor land due to the lack of addition of organic matter and continuously inundated irrigated rice fields, causing the production of greenhouse gas emissions, such as methane gas (CH4), to increase. The study aims to determine the impact of organic fertilizers and rice varieties on rice yield, methane emissions, and the feasibility of farming in nutrient-poor rice fields. The study used a randomized block design in factorial with four replicates. The first factor is the type of organic fertilizers (compost of rice straw and goat manure), and the second factor is the variety of rice (Ciherang, Inpari 20, and Inpari 30). The results showed that the productivity of Inpari 20 (8.02 t·ha−1) was significantly higher than that of Inpari 30 (6.10 t·ha−1) and Ciherang (6.91 t·ha−1). The highest yields of Harvest Dry Grain (HDG) to Milled Dry Grain (MDG) were the Inpari 20 (88.23%), Inpari 30 (86.94%), and Ciherang (85.04%). Methane (CH4) emissions were highest in the Ciherang variety (56.4 kg h−1 season−1), followed by Inpari 30 (40.8 kg h−1 season−1), and lowest in Inpari 20 (22.3 kg h−1 season−1). Compared to Inpari 30 and Ciherang varieties, the Inpari 20 variety with rice straw compost has broad development viability in nutrient-poor paddy fields (highest R/C ratio and break-even point). More research on organic rice is needed to determine the productivity and emissions (methane, nitrite, carbon dioxide).