Raising livestock can significantly help Nepali farmers avoid
burning crop residues — a practice known to generate atmospheric pollutants
that increase warming, and severely impact health, says a new
study.
Published this month in the journal Environmental Pollution, the
study combined bottom-up estimates from the field and satellite imagery to
develop an emission inventory attributable to crop residue burning for every
square kilometre of Nepal, extending across the high Himalayas and into the
‘terai’ (lowland) plains, bordering India.
Institute
for Advanced Sustainability Studies, Potsdam
“Crop
residue… is burned in developing countries… to cheaply eliminate post-harvest
residues,” says Bhupendra Das, lead study author and researcher at the Tribhuvan
University, Kathmandu. “However, the inefficient open burning generates
significant amounts of pollutants such as aerosols (particulate matter, black
carbon, organic carbon), trace gases (nitrogen oxides, carbon monoxide,
non-methane volatile organic compounds, ammonia, sulfur dioxide), and greenhouse gases (carbon dioxide, methane, nitrous
oxide).”
Significantly, the study also found that open burning of crop residue is less
likely to occur where farmers have more livestock per
hectare. “So, raising livestock by local farmers,
which provides additional incomes, could be an important mitigation measure to
reduce open burning,” says Das, who is also a researcher at the Institute for
Advanced Sustainability Studies, Potsdam, Germany.
Raising livestock will provide an opportunity for farmers in alternative energy production
such as biogas, explains Das to SciDev.Net, pointing to Nepal’s
existing commercial biogas plants at Nawalparasi and at Biratnagar.
“These plants produce piped or bottled, clean energy cooking gas as a
substitute to imported liquid petroleum gas, which is expensive in a
resource-poor and landlocked country like Nepal.”
According to Das, cattle dung if left lying around generates methane. which is
a worse greenhouse gas than carbon dioxide. On the other hand, cattle dung is
ideal feedstock for biogas plants which produce methane that can be tapped for
commercial or domestic use. “Nepal needs to invest in more biogas plants to
save on imports and reduce dependency on fossil fuels.”
Analysis of temporal distribution from satellite data showed
that around 54 per cent of total emissions occurred in the month of April and
dropped to zero during July to September. “This is valuable for policy makers
and other involved in air quality management,” says Das.
A 2018 study led
by Das had already shown the global warming potential of pollutants such as CO2, CH4, N2O
and black carbon generated by the burning municipal solid waste in Nepal for
its negative health impacts.
Black carbon, a major pollutant from open burning is known to have a high
impact on glacier melt in the vast Hindu Kush-Himalaya ice sheet,
according to the Intergovernmental Panel on
Climate Change’s Special Report on the Ocean and Cryosphere in a Changing
Climate, released in 2019.
“Black carbon can also disrupt the photosynthesis process in plants, reducing agricultural productivity,
though this is a subject for further research,” adds Das.
Studies have shown that combine harvesters can be modified to collect crop
residue to be turned into animal
feed, for alternative energy production and as raw materials for such
industries as mushroom cultivation, paper production and fuel in brick kilns.
This
piece was produced by SciDev.Net’s Asia & Pacific desk.
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