Agriculture pollution

Dr. Parveen Kumar
India is the second largest agricultural based economy featured by the generation of large amount of agricultural related waste. This agricultural related waste is a major source of pollution. Pollution refers to the presence of harmful substances or contaminants into the natural environment that cause adverse changes much to the disadvantage of living things present on this planet. Pollution can take the form of any substance (solid, liquid, or gas) or energy (such as radioactivity, heat, sound or light). Substances that make up the pollution are called as Pollutants and these can be either foreign substances/energies or naturally occurring contaminants. Although environmental pollution can be caused by natural events, it has an anthropogenic source too; that is, a source created by human activities. Studies reveal that in 2015, pollution killed 9 million people worldwide.

Today is National Pollution Control Day

The major forms of pollution include water pollution, air pollution, noise pollution, plastic pollution, soil contamination, radioactive contamination and thermal pollution.
In the past few decades pollution from agriculture has been threatening all of us and has become a cause of worry for the agricultural scientists, policy makers and planners. Agricultural pollution refers to biotic as well as abiotic byproducts of farming practices that result in contamination or degradation of the environment and surrounding ecosystems, and/or cause injury to humans and their economic interests. The pollution may come from a variety of sources, ranging from point source such as water pollution (from a single discharge point) to more diffuse, landscape-level causes, also known as non-point source pollution and air pollution. Once in the environment these pollutants can have both direct effects in surrounding ecosystems, i.e. killing local wildlife or contaminating drinking water and downstream effects such as dead zones caused by agricultural runoff is concentrated in large water bodies. Pollutants from agriculture also greatly affect water quality and can be found in lakes, rivers, wetlands, estuaries, and groundwater. Pollutants from farming include sediments, nutrients, pathogens, pesticides, metals and salts. Livestock has an outsized impact on pollutants that enter the environment. Bacteria and pathogens in manure can make their way into streams and groundwater if grazing, storing manure in lagoons and applying manure to fields is not properly managed. Air pollution caused by agriculture through land use changes and animal agriculture practices have an outsized impact on climate change. The different sources of agriculture pollution include:
GHGs and agriculture: Agriculture is an important source of GHG emissions. Agriculture related emissions from agriculture are mostly in the form of Methane, Nitrous oxide. According to the Global Carbon Atlas, India ranks third in total GHG emissions. Agricultural emissions in India are primarily from the livestock sector (54.6%) in the form of methane emissions due to enteric fermentation, use of nitrogenous fertilizers (19%), rice cultivation (17.5%), burning of crop residues (2.1%)
Crop Residue burning: According to the Indian Ministry of New and Renewable Energy (MNRE), India generates on an average 500 million ones of crop residue in a year. Although the majority of this crop residue is used as fodder, fuel or for other domestic and industrial purpose. There is still a surplus of 140 MT of which 92 MT is burnt every year. Burning of crop residues as has been noticed in several states of north India is also a major source of air pollution. It is responsible for air pollution, public health concerns, green house gas emissions, radiation imbalance and declining soil organic matter and soil productivity. Although, burning crop residues is a crime under section 188 of the IPC and under Air and Pollution Control Act, yet the practice is going on more so in Punjab and Haryana where farmers burn the residues of Kharif crops like Paddy as they consider it an obstacle for performing tillage and other agricultural related operations for the rabi season crops.
Plant Protection Chemicals:
Different types of chemical insecticides, pesticides and herbicides are applied to agricultural land to control insects, pests and unwanted plants that disrupt crop production by competing with main crop for nutrients and other resources. These persist and accumulate in soils and contaminate the soil thereby altering various soil microbial processes. With this, they also increase plant uptake of the chemical, and are toxic to soil organisms. Pesticides can also accumulate in animals that eat contaminated pests and soil organisms. In addition, pesticides can be more harmful to beneficial insects, such as pollinators, and to natural enemies of pests (i.e. insects that prey on or parasitize pests) than they are to the target pests themselves. Pesticide leaching occurs when pesticides mix with water and move through the soil, ultimately contaminating groundwater.
Chemical Fertilizers
Different types of chemical fertilizers that are used to provide crops with additional sources of nutrients, are Nitrogen, Phosphorus, and Potassium. Nitrogen fertilizers supply plants with forms of nitrogen that are biologically available for plant uptake; namely NO3? (nitrate) and NH4+ (ammonium). This increases crop yield and agricultural productivity, but it can also negatively affect groundwater and surface waters, pollute the atmosphere, and degrade soil health. Not all nutrient applied through fertilizer are taken up by the crops, and the remainder accumulates in the soil or is lost as runoff. Nitrate fertilizers are much more likely to be lost to the soil profile through runoff because of its high solubility and like charges between the molecule and negatively charged clay particles. Besides these other chemical fertilizers also release many greenhouse gases which contribute to climate change.
Metals: The major source of heavy metals (e.g. lead, cadmium, arsenic, mercury) in the agriculture production systems are fertilizers, organic wastes such as manures, and industrial byproduct wastes. Inorganic fertilizers especially represent an important pathway for heavy metals to enter soils. Besides, some farming techniques, such as irrigation, can lead to accumulation of selenium (Se) that occurs naturally in the soil, which can result in downstream water reservoirs containing concentrations of selenium that are toxic to wildlife, livestock, and humans. Steel industry wastes, which are often recycled into fertilizers due to their high levels of zinc (essential to plant growth), can also include the following toxic metals: lead, arsenic, cadmium, chromium, and nickel. The most common toxic elements in this type of fertilizer are mercury, lead, and arsenic. These potentially harmful impurities can be removed during fertilizer production; however, this significantly increases cost of fertilizer.
Soil Erosion:
Agriculture contributes greatly to soil erosion and sediment deposition largely due to our crude agricultural practices. It is estimated that agricultural land degradation is leading to an irreversible decline in fertility on about 6 million ha of fertile land each year. The accumulation of sediments in runoff water affects water quality in various ways. Sedimentation can decrease the transport capacity of ditches, streams, rivers, and navigation channels. It can also limit the amount of light penetrating the water, which affects aquatic biota.
The United Nations Food and Agriculture Organization (FAO) predicted that 18% of anthropogenic greenhouse gases come directly or indirectly from the world’s livestock. This report also suggested that the emissions from livestock were greater than that of the transportation sector.
National Pollution Control Day: The National Pollution control day is celebrated every year on December 02 in the memory of the precious lives that were lost as a result of the accidental leakage of the poisonous Methyl Isocyanate gas from Union Carbide factory on the intervening night of Dec. 02 and 03 in 1984. This day is meant to raise awareness about various issues related to pollution and reflects our commitment to take all out measures to combat this menace
In the present era when agriculture sector itself is being confronted with many serious challenges, the pollution emerging from this sector has put a question mark on the very sustainability of this sector. There is thus an urgent need to practice and propagate technologies which are eco friendly. At the same time onus also lies on the farming community not to go for practices which pollute the environment and threaten our planet just for small monetary gains.