Abdullah Al Mahmud’s Post

View profile for Abdullah Al Mahmud, graphic

Research Field Operations Lead @ Plant Growth Core Lab, KAUST

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]

  • Conceptual diagram of wetland porewater, surface water, and groundwater and associated carbon (C) constituents including gaseous (red) and 
dissolved (dark blue) carbon dioxide (CO2, pCO2), methane (CH4, pCH4), and oxygen  (O2, DO), Dissolved Organic C (DOC), Dissolved Inorganic C (DIC), Particulate Organic C (POC), and Particulate Inorganic C (PIC). Note that porewater is technically located in the unsaturated zone below 
the soil surface and above the water table; however, the term ‘porewater’ is typically used in the wetland scientific literature 
to indicate any water near the sediment surface, such as in the root zone, even if soils are saturated and below the water 
table.
Md Abdul Halim, PhD

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.

7mo

Useful tips

Like
Reply
Dr. Mugesh Raja

Assistant Professor | DSAC | Soil Science & Agricultural Chemistry | TNAU, Coimbatore

7mo

Interesting!

Like
Reply
See more comments

To view or add a comment, sign in

Explore topics