Effect of Mid-Season Drainage, Sulphate Addition and Blue Green Algae on the Yield, Methane Emission and Carbon Flux from Rice Fields

The current study was undertaken with the objective of estimating methane emission and carbon flux with modified management practices (mid season drainage, zero tillage and sulphate application) using DNDC model and calibration and validation of the model at field scale. Methane (CH4) and carbon dioxide (CO2), two greenhouse gases (GHG) linked to agricultural activities are key contributors to climate change caused by human activity. Crop management techniques such stubble manuring, puddling, sowing or transplanting, water management, and harvesting have a significant impact on the carbon exchange between rice fields and the atmosphere. Mid-season irrigation water pond draining stops the ongoing submergence. The research studies reported that mid-season drainage reduced CH4 emissions. Hence an experiment was conducted at Agricultural Research Station, Tamil Nadu Agricultural University, Bhavanisagar with an objective of identification of management practices which emits low level of methane gas from rice ecosystem using rice variety CO 50 as test crop and modified management practices and sulphate application as treatments. Biometric observations were recorded and methane emission was quantified at 15 days interval from transplanting to harvest. Ten clumps of rice plants were sampled and Photosynthetically Active Radiation (PAR) was recorded at 15 days interval. The DeNitrification-DeComposition (DNDC) model was run for the treatment conditions. The field observations revealed that methane emission was low (41%) in the treatment of mid-season drainage when compared to control. The combination of mid-season drainage as well as Blue Green Algae (BGA) + Methylotroph along with Recommended Dose of NPK (T7) application reduced the methane emission up to 48 per cent compared to control. The results generated from the DNDC model also revealed the similar results. The DNDC model captures the major impacts of water and N on GHG emissions from paddy cultivation. The analysis suggested that the model can be applied for studying the GHG related issues in rice cropping systems.