Analisis Sistem Irigasi Evapotranspiratif terhadap Emisi Gas Metana (CH4) pada Budidaya Padi dengan Berbagai Skenario Tinggi Muka Air

Abstract

Emisi gas metana (CH4) dari lahan sawah tergenang merupakan salah satu kontributor utama gas rumah kaca dari sektor pertanian. Penelitian ini bertujuan untuk menganalisis hubungan antara tinggi muka air (TMA) dan fluks CH4 pada budidaya padi dengan sistem irigasi evapotranspiratif. Penelitian dilakukan di greenhouse menggunakan empat rezim irigasi, yaitu tergenang (RT), basah (RB), kering (RK), dan mid-season drainage (RM). Pengambilan sampel CH4 dilakukan setiap minggu sebanyak dua ulangan dengan menggunakan metode closed chamber. Hasil menunjukkan bahwa suhu tanah, kelembaban tanah, dan pH berhubungan positif dengan fluks CH4, sedangkan DHL tidak berpengaruh nyata. Total fluks CH4 tertinggi terdapa pada RT sebesar 44,04 kg/ha/musim, diikuti oleh RM sebesar 13,69 kg/ha/musim, RB sebesar 0,67 kg/ha/musim, dan terendah pada RK sebesar –27,67 kg/ha/musim. Analisis regresi menunjukkan hubungan positif antara TMA dan fluks CH4 dengan R² = 0,8323. TMA optimal untuk mitigasi CH4 berada pada kisaran –5 hingga 0 cm.

Methane (CH4) emissions from flooded rice fields are one of the main contributors to greenhouse gases in the agricultural sector. This study aimed to analyze the relationship between water level and CH4 flux in rice cultivation under evapotranspirative irrigation systems. The experiment was conducted in a greenhouse using four irrigation regimes: continuous flooding (RT), moist (RB), dry (RK), and mid-season drainage (RM). CH4 samples were collected weekly with two replications using the closed chamber method. The results showed that soil temperature, soil moisture, and pH were positively correlated with CH4 flux, whereas electrical conductivity had no significant effect. The highest total CH4 flux was observed in RT at 44.04 kg/ha/season, followed by RM at 13.69 kg/ha/season, RB at 0.67 kg/ha/season, and the lowest in RK at –27.67 kg/ha/season. Regression analysis revealed a positive relationship between WL and CH4 flux with an R² of 0.8323. The optimal water level for CH4 mitigation was determined to be between –5 to 0 cm.