Dr Md Khairul Alam1, Professor Richard W Bell2, Dr M E Haque2, Professor Abdul Kader2
1Bangladesh Agricultural Research Institute, Gazipur, Bangladesh, 2Murdoch University, Perth, Australia
Little is known about the impact of conservation agriculture (CA) practices on soil carbon dynamics in the intensive triple-cropping, rice-based systems of the Eastern Gangetic Plain (EGP). Our aim was to determine whether CA in these systems involving non-puddled transplanting (NP) of wetland rice and strip planting of dryland crops plus increased residue retention would increase the C storage in soils relative to conventional crop establishment practices. Long-term field experiments were studied in two locations of northwestern Bangladesh to determine C turnover as well as examining C cycling under three soil disturbance levels (conventional tillage-CT, strip planting-SP and bed planting-BP) in combination with low residue (straw) retention(LR) and increased residue retention (HR) in Calcareous Brown Floodplain (Alipur) and Grey Terrace soil (Digram). The total nitrogen(N), organic C(SOC), microbial biomass C (MBC) and water-soluble C(WSC) values were measured in soil samples collected at different stages during the growth of the 13th and 14th crops at Alipur and the 12th and 13th crops at Digram since treatments commenced. At each location, SP and BP with LR or HR retained more SOC from C inputs than CTHR and CTLR. In general, the CO2 emissions under SPLR and SPHR were 13 to 59 % lower than those under CT and BP with LR and HR. The higher levels of C mineralization were associated with higher WSC contents in the soil. Similarly, in SPLR and SPHR, the potentially mineralizable C was higher, while decay rate constant was lower. The HR with SP and NP after 14 crops at Alipur and 13 crops at Digram modified the C cycle by decreasing C emissions and increasing the levels of total organic C in the soil. The application of both minimal soil disturbance and HR enhanced SOC concentrations in the soils under rice-based cropping systems on the EGP.
Dr Alam has 13 years of experience on land management and crop production. He has expertise on soil C sequestration, crop establishment practices, nutrient management, global warming potential mitigation. Dr Alam has also published manuscripts on the research activities in different reputed journals. Dr Alam has recently finished his PhD on “Assessment of soil carbon sequestration and climate change mitigation potential of conservation agriculture practices on the Eastern gangetic Plains”.