Emisi CO2 dan CH4 pada Padi Sawah Menurut Fase Pertumbuhan dan Variasi Pengenangan

Abstract

Emisi gas rumah kaca (GRK) dari lahan sawah menjadi perhatian utama dalam mitigasi perubahan iklim sektor pertanian. Penelitian ini bertujuan menganalisis dinamika emisi CO2 dan CH4 serta hubungannya dengan tinggi muka air (TMA) dan Leaf Area Index (LAI) pada fase vegetatif dan generatif di dua sistem budidaya: jajar legowo dengan pendekatan Alternate Wetting and Drying (AWD) dan konvensional dengan genangan kontinu. Pengukuran fluks gas dilakukan setiap hari pagi dan siang menggunakan metode closed chamber di Desa Teguhan, Kabupaten Madiun, pada November 2025 hingga Februari 2026. Hasil penelitian menunjukkan bahwa hubungan TMA dengan emisi CO2 dan CH4 bersifat dinamis dan berubah menurut fase pertumbuhan, namun secara statistik tidak signifikan (R² = 0,0087–0,1021). Sebaliknya, LAI memiliki pengaruh yang lebih dominan, terutama pada fase generatif. Pada sistem konvensional siang hari, LAI mampu menjelaskan 51% variasi emisi CO2 (R² = 0,510; p = 0,00004), mencerminkan dominasi fotosintesis. Pada sistem jajar legowo, LAI berpengaruh signifikan terhadap emisi CH4 pada fase generatif (R² = 0,184; p = 0,013), mengonfirmasi peran tanaman sebagai saluran transportasi gas (efek cerobong). Penerapan AWD di lapangan tidak konsisten dengan protokol baku karena bergantung pada keputusan petani, sehingga efektivitasnya dalam menekan emisi CH4 tidak terlihat signifikan. Penelitian ini berimplikasi bahwa pengelolaan air berbasis fase pertumbuhan memerlukan konsistensi penerapan, serta LAI merupakan faktor yang lebih berpengaruh terhadap dinamika emisi GRK dibandingkan TMA pada fase generatif.

Greenhouse gas (GHG) emissions from paddy fields are a major concern in climate change mitigation in the agricultural sector. This study aimed to analyze the dynamics of CO2 and CH4 emissions and their relationship with water table depth (WTD) and Leaf Area Index (LAI) during vegetative and generative stages in two cultivation systems: jajar legowo with Alternate Wetting and Drying (AWD) approach and conventional system with continuous flooding. Gas flux measurements were conducted daily in the morning and afternoon using the closed chamber method in Teguhan Village, Madiun Regency, from November 2025 to February 2026. The results showed that the relationship between WTD and CO2 and CH4 emissions was dynamic and varied according to growth stages but was statistically insignificant (R² = 0.0087–0.1021). In contrast, LAI had a more dominant influence, especially during the generative stage. In the conventional system during the afternoon, LAI explained 51% of CO2 emission variability (R² = 0.510; p = 0.00004), reflecting the dominance of photosynthesis under stable flooding conditions. In the jajar legowo system, LAI significantly influenced CH4 emissions during the generative stage (R² = 0.184; p = 0.013), confirming the role of rice plants as a gas transport pathway (chimney effect) through aerenchyma tissue. The implementation of AWD in the field was inconsistent with standard protocols due to its dependence on farmers' decisions, so its effectiveness in reducing CH4 emissions was not significantly observed. This study implies that growth stage-based water management requires consistent application, and LAI is a more influential factor than WTD in controlling GHG emission dynamics during the generative stage.