Agricultural Emissions and pollution
Every country's economic, environmental, and social well‐being is intricately linked to a healthy, well‐performing agricultural sector. In our country it becomes more important as growth of the agricultural sector has been fluctuating for a long time. The economic survey (2019-20) indicates that contribution of agriculture to the Gross value added (GVA) has decreased from 18.2% in 2014-15 to 16.5% in 2019-20. However, agriculture is facing the triple challenge of increasing production to meet the growing food demand, adapting to changing climatic conditions, and reducing agricultural emissions (Greenhouse gases (GHG) and non-GHG emissions) from the fields, globally.
At the same time, India has expressed its determination in its climate pledges, and nationally determined contributions (NDCs), under the Paris Agreement. This is indeed for the first time when our government has also restated firmly to step up and strengthen its nationally determined climate action plans through a long-term strategy, which indicates India’s unwavering commitment to the global efforts in tackling climate change. In that context, it would be interesting to know that our country is the third-largest emitter of greenhouse gases (GHG) in the world after the USA and China and therefore, to reduce emissions at a global level, India has a vital role to play.
“Our population is 1.3 billion which is the world's second-largest but we are the seventh-largest country in total area (3.288 million sq km)”. Agricultural activities contribute significantly to the GHG emissions. Methane (CH4) and nitrous oxide (N2O) were the two main gases emitted by agricultural activity. In addition to methane and nitrous oxide, agricultural activities have been linked to the emission of other dangerous gases and pollutants. These include carbon dioxide, ammonia, hydrogen sulfide, and airborne particulate matter, which has been linked to health problems. The situation becomes more challenging when agriculture, with its allied sectors, is the largest source of livelihoods in India with almost 70 percent of its rural households are dependent primarily on agriculture for their livelihood. Consequently, scientists and policymakers are faced with the dual challenge of meeting the growing demand for food whilst also reining in on GHG emissions.
Population growth will lead to an increase in food demand, which will exert pressure on crop production and likely increase the agricultural crop residue. The different studies were carried out to estimate the atmospheric emissions of various pollutants from crop residue burning using the Intergovernmental Panel on Climate Change guidelines. In India 488 Mt of total crop residue was generated during 2017, and about 24% of it was burnt in agricultural fields. This resulted in emissions of 824 Gg of Particulate Matter (PM2.5), 58 Gg of Elemental Carbon (EC) and 239 Gg of Organic Carbon (OC). Additionally, 211 Tg of CO2 equivalent greenhouse gases (CO2, CH4, N2O) were also added to the atmosphere. Trend analysis in a Business As Usual (BAU) model shows that crop residue burning emissions will increase by 45% in 2050 having 2017 as the base year.
Northwestern India is known as the “breadbasket” of the country producing two-thirds of food grains, with wheat and rice as the principal crops grown under the crop rotation system. Agricultural data from India indicates a 25% increase in the post-monsoon rice crop production in Punjab during 2002–2016. NASA’s A-train satellite sensors detect a consistent increase in the vegetation index (net 21%) and post-harvest agricultural fire activity (net ~60%) leading to nearly 43% increase in aerosol loading over the populous Indo-Gangetic Plain in northern India. The ground-level particulate matter (PM2.5) downwind over New Delhi shows a concurrent uptrend of net 60%. An efficient crop residue management system is critically needed towards eliminating open field burning to mitigate episodic hazardous air quality over India.
Therefore, we should adopt sustainable approaches and propose an integrated crop residue management model to minimize the adverse impact of agricultural waste burning on human health and the environment. Also, we need more research to cut the amount of fertilizer application in cropping seasons without significant loss of crop yield in arable lands, which might be plant demand-based (precision farming), or adoption of some innovative approaches like biochar-based formulations in place of conventional blanket recommendation practices. Policy regulations are needed to cut the emissions from the agricultural sector and our Honorable Prime minister has also encouraged the scientific fraternity to look for the ways to reduce mineral fertilizer use. Techniques including better manure storage, precision nutrient application, and air-breaks between farms can all help decrease the effect of agricultural practices on air quality.