Water-filled pore space (WFPS) is pivotal in the emission of greenhouse gases from rice paddies. It affects the soil's aerobic and anaerobic balance, thus influencing the microbial activities that generate methane (CH₄) and nitrous oxide (N₂O). WFPS is the measure of the soil's void volume that water can occupy, which is determined by the soil's porosity and moisture levels. The adoption of Alternate Wetting and Drying (AWD) in water management for rice cultivation can markedly decrease methane emissions by 30-70% without compromising crop yield. AWD, which cycles between periods of flooding and drying, suppresses the bacteria responsible for methane production during the drying phases. Research indicates that AWD, on average, cuts methane emissions by 48% in comparison to constant flooding, following the 2006 IPCC guidelines. While AWD may affect nitrous oxide (N₂O) emissions differently, with some instances showing a rise due to increased nitrification in dry spells, the overall impact on greenhouse gas emissions is beneficial. The decrease in methane generally surpasses any rise in N₂O emissions. For the most effective reduction of greenhouse gases without sacrificing rice yield, it's essential to customize AWD methods to the local environment, taking into account soil type, climate, and the particular AWD protocol applied. Water-Filled Pore Space (WFPS) is critical for soil microbial activity and greenhouse gas (GHG) emissions. Here are the key points: 1. Microbial Activity and WFPS: - WFPS measures the percentage of soil pores occupied by water. Higher WFPS leads to more anaerobic conditions, affecting microbial activities. - As WFPS rises, it restricts oxygen flow, benefiting anaerobic microorganisms. - These microorganisms are involved in the production and consumption of GHGs such as CO₂, CH₄ (methane), N₂O (nitrous oxide), and N₂ (nitrogen gas). 2. GHG Emissions and WFPS: - CO₂ Emissions: * Soil treated with septic tank effluent (STE) reaches peak CO₂ emissions at WFPS values between 0.5 and 0.8. * Effluent from a single-pass sand filter (SFE) shows noticeable CO₂ emissions primarily in the B horizon soil. - CH₄ Emissions: * Observable only in STE-treated soil, with emissions rising linearly with WFPS in the C horizon. - N₂O Emissions: * Increase linearly with WFPS in both B and C horizon soils treated with SFE. - N₂ Emissions: * N₂ production exceeds that of N₂O. * Highest at the lowest WFPS values, diminishing as WFPS goes up. 3. Implications: - The response of these gases to WFPS is influenced by soil type and texture. - The availability of organic C and NO₃ does not significantly limit GHG emissions. - Variables such as acetate or NO₃ addition can modify emission levels. [https://lnkd.in/eGYKTgMJ]
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Doctor of Philosophy (Ph.D.) in Environmental Remediation || Soil Residual Pesticide II PGPR II Plant Growth Promotion II Micro-composite Fertilizer II Abiotic Stress II Sustainable Soil Health Management.
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