Abiotic variables controlling N mineralization and greenhouse gas emissions from a continuously and intermittently flooded paddy soils depth profile

Nitrogen (N) and irrigation water has been crucial to achieve rice grain food security in Asia by their rising cost and demand. Irrigated lowland rice accounts for 50% of the total rice area, which contributes 75% of the global rice harvest. In flooded rice field both water and N use efficiency decreased due to their losses via different processes. By 2025, 15 out of 75 million hectare of flood-irrigated rice in Asia will experience water shortage. To use water more efficiently in rice farming water-saving irrigation managements especially alternate wetting and drying (AWD) are promoting widely in South-East Asia, and some extent in Bangladesh. Each technique helps to lessen non-beneficial water flows and N losses from paddy fields. However such changes in alternate aerobic and anaerobic cycling is expected to alter the soil biochemical properties like pH, redox (Eh), availability of oxidants for SOM degradation, the state of labile OC etc. All these abiotic driving variables also differs strongly between soil depth increments and greatly influence N availability, and green house gas emissions. But the relation of these dynamic depth profiles with bulk soil N mineralization and green house gas emissions have not been resolved for young floodplain paddy soils in Bangladesh, especially not under AWD.

 Irrigated rice fields Bangladesh

Objectives:

In this project we are interested to understand how depth distributed redox, moisture, dissolved OC, soil solution Fe and Mn drive: N mineralization, the most important process to provide N for rice plants,  and  2º Green house gas emissions (CH4 CO2, N2O) in continuously and intermittently flooded paddy fields with or without N fertilizer application.

 

Researcher: MSc. Masuda Akter
Period : 2013-2017
Financing body : VLIR-UOS
Promoter : Professor Steven Sleutel and dr. Md. Abdul Kader