Agriculture is being practiced for hundreds of years providing employment, food, and necessities of life to the majority of the world. With the rising demand for food, agriculture is also flourishing and gradually increasing demand for agriculture land. However, apart from the positive aspects of agriculture, there are several negative effects of agriculture on the environment which are creating serious problems for a sustainable environment.
Researchers are now trying to discover the problems and their solutions to overcome the negative effects of agriculture. Globally, agriculture is the biggest sector with the highest employment rate. However, it still comes with great risks of environmental degradation.
Top 16 Negative Effects of Agriculture on the Environment
- Soil/Land degradation
- Climate change
- Pest problems
- Industrial & agricultural waste
- Livestock grazing
- Chemical fertilizer
- Point source pollution
- Non-point source pollution
- Removal of riparian shading
- Stream modification
- Genetic engineering
- Issues by region
Degradation of land and soil is one of the most serious negative effects of agriculture on the environment. It significantly endangers agricultural sustainability and increases water and soil erosion during rains and flowing waters. About 141.3-million-hectare of global land are facing serious erosion issues due to uncontrolled deforestation, over-grazing, and the use of inappropriate cultural practices.
Alongside the rivers, about 8.5-million-hectare land, rising groundwater tables are badly affecting the ability of the land to hold plants and allow the application of cultivation practices. Similarly, intensive agriculture and increased use of irrigations also result in soil salination, waterlogging, etc.
On the other hand, soil degradation results in a decline in soil quality, soil biodiversity, and essential nutrients affecting crop productivity. Some of the common factors for soil degradation are salination, waterlogging, excessive use of pesticides, soil structure and fertility losses, changes in soil pH, and erosion.
Soil erosion is one major factor of soil degradation, results in the loss of highly fertile topsoil which is the key component of agriculture and crop production. Soil degradation also severely affects the soil microbial communities which mainly take part in natural nutrient cycling, disease and pest control, and transformation of soil chemical properties.
Some of the kinds of effects which soil/land degradation is causing and taking part in a significant part of the area:
- Nutrient deficiency.
- Nutrient imbalance particularly micro- nutrients.
- Loss of organic matter.
- Water and wind erosion.
- Lowering of the ground water table.
- Soil salination.
- Groundwater contamination due to the high use of nitrogen.
Deforestation leads to the large-scale clearing and cutting of the world’s forests which ultimately causes great damage to the habitat. Agriculture is one major reason for deforestation, as, with the rising demand for food, more land is required for pastures or crops, therefore rapid cutting and burning of frosts is taking place. Norman Myers, a British ecologist, has categorized the reasons for deforestation, 5% – cattle raising, 19% – heavy logging, 22% – palm-oil plantation, and 54% – slash and burn agriculture.
The major reasons for deforestation:
- Population pressure: Increase in demand for fuel, wood, and food.
- Poorly planned developmental projects.
- Unpredictable forest fires due to rising global warming.
- Fewer afforestation activities.
Deforestation is a leading cause of climate change and habitat loss for millions of species. Therefore, it turns to be one of the significant negative effects of agriculture on the environment. Trees act as natural atmosphere cleaners absorbs CO2 and act as carbon sinks for this major greenhouse gas. Cutting trees means removing the natural absorbers and let CO2 penetrate the atmosphere which will increase the concentration of CO2 in the air, exacerbating climate change.
Removal of trees results in loss of shade which causes the soil to dry quickly and fails to restore the natural water cycle by recycling water-vapors to the environment. Without trees, potential and fertile landscapes will turn into barren deserts and will cause extreme temperature fluctuations in the environment.
Removing trees can lead to faster evaporation of water due to lack of shades and will also adversely affect the water-quality. Later, this poor water quality will affect the rest of the ecosystem and result in uneven watering, increased salinity, and death of plants.
There are many different agro-climatic conditions in the world, in which a wide-variety of plants and animals live. Due to the increased commercialization of agriculture, gradually a variety of no. of plants and animals are endangered or extinct. Farmers are prioritizing the cultivation of high-yielding crops for more profit which is causing a decline in the cultivation of less profitable crops resulting in the loss of several native species.
Biodiversity contributes to agricultural development by supporting production in many different ways. For example:
- Birds and spiders can act as biological control.
- Earthworms can act as natural cultivators.
- Bees can help in more pollination and fertilization.
Agricultural expansion is causing severe damage to the habitat of native species. As for more profit and production farmers are moving toward the use of hybrid seeds and genetically modified crops which are causing huge damage to native species. Due to the loss of native plant species, other living communities are also facing survival problems or genetic modification which are making them more harmful to the natural ecosystem.
Among the negative effects of agriculture on the environment, climate and agriculture are two globally interconnected processes that move ahead in a parallel manner. Therefore, changing climate adversely affect agricultural productivity and play a significant role in global warming, including temperature fluctuations, unpredicted precipitation, and glacial run-off. Thus, these attributes highly affect the ability of an ecosystem to produce enough food for the population.
Agriculture plays a significant impact on global climate, mainly through the emission of greenhouse gases such as CO2, CH4, and nitrous oxide. Additionally, modern agricultural practices such as the use of synthetic fertilizers, tillage, etc., also emit ammonia, nitrate, and many-other residues of synthetic chemicals that severely affect natural resources like., water, air, soil, and biodiversity.
For better productivity farmers repeatedly use tillage practice on agricultural land which results in loss of earth’s cover, which influences the earth’s ability toward solar radiations, heat, and light.
Due to the change in the crop harvesting pattern, increase in irrigated areas, and the higher intensity of cultivation, the problem with pests becoming serious day by day. A major reason for the increase in severity of pests is the uncontrolled use of pesticides. Pests are becoming resistant to available pesticides and returning with more harmful effects.
The population of birds and insects has declined significantly due to loss of habitat and changing climate, resulting in a lack of natural biological control. High and uncontrolled use of hazardous pesticides has a direct impact on farmers, consumers, and animal health. On the other hand, residual pesticides are way more dangerous for humans and animals and pose serious health risks.
Industrial & Agricultural Wastes
Among several negative effects of agriculture on the environment, industrial & agricultural waste is the most dangerous and harmful for the ecosystem and humans. Agricultural remains of several crops like., rice straw and hull, because of improper handling act as agricultural waste. To remove this waste farmers usually practice burning methods which result in the production of high CO2 and CO levels in the air, causing severe respiratory problems in humans and animals. Agricultural waste needs to be recycled through the processing of by-products by enterprises such as fishing, poultry, dairy, etc., as well as plowing for maintaining organic matter.
Use of mechanization in agriculture also results in several negative ecological impacts because for their effective application they also need several resources like electricity, diesel, gasoline, etc. which end up in smoke, loss, and high prices. Pollution from fertilizer industries is also contaminating the air and water which negatively impacts the ecological system of a country. This non-degradable waste cause toxicity in plants and animals, especially aquatic life, and also imbalance the soil nutrients.
Recently, farmers started using plastic sheets as mulch to cover soil (50-70%) for the efficient practice of drip irrigation to enhance crop productivity. By using pesticides with plastics, runoff pesticides can be more easily transported to wet-lands or streams, causing severe deformation of water reserves. In the US, the use of plastic mulch increased to 110 million-pounds and after using it all ends up in landfills causing ecological instability.
Agriculture accounts for 70% of the total freshwater globally. Expert predictions estimate that the need for water will increase by another 15% or more by 2050 to feed a growing population. On the other hand, depletion of aquifers, rivers, and groundwater reservoirs are additionally contributing to global water losses. Many agriculturists believe that irrigation is the foundation of many negative effects of agriculture on the environment.
Apart from water depletion, several other negative effects are also associated with irrigation e.g., salinity, waterlogging, increase in anaerobic decomposition, are poisoning plant roots, and lowering plant yield. Excessive Irrigation leads to increased evaporation, which affects both atmospheric temperature and pressure.
Studies have proven that irrigation of agricultural lands can affect the distribution of rainfall not only in the irrigated areas but even thousands of kilometers away.
In New Zealand, after every 12 years, the total irrigated agricultural land has doubled since the 1970s. Currently, it is about 720,000 hectares, concluding about 6% of total arable land in New Zealand, with an agricultural GDP contribution of about 20%.
Problems associated with irrigation:
- Depletion of water reservoirs.
- Water contamination due to residual chemicals and wastes.
- Seepage of polluted water to water reservoirs.
Most of the agricultural land is mainly used as pasture. In the western US, hundreds- of millions- of acres are reserved for this purpose – much more than any other. Farm animals are responsible for most of the release of global greenhouse gases, especially methane. Livestock grazing is one of the basic negative effects of agriculture on the environment. Furthermore, overgrazing is also a serious problem for a sustainable environment.
Sometimes forage areas are so heavily consumed that grasses fail to regenerate; their root system is so much damaged that the native species ultimately end up dying. Near riverbeds and other coastal areas, the combined impact of overgrazing and animal faeces pollute or degrade natural water sources.
It is also believed that land trampling by cattle and other animals destroys the topsoil and subject it to water and wind erosion resulting in the nutrient runoff. It is also explained that while crossing streams, the probability of cattle excretion in the stream is 50 times higher than on land.
Use of nitrogen and phosphorous-containing synthetic fertilizers in agriculture gained more popularity during World War II. And today in modern agriculture, it gained a central position among agricultural practices. Synthetic fertilizers proved to be very effective for the cultivation of corn, rice, wheat, and other cereals and improved the actual yield. Today, China is the leading nitrogen fertilizer producer in the world.
Chemicals no doubt helped the farmers to double the yield, but it is also the main contributor of reactive nitrogen to the environment, about 600%. Excess deposition of phosphorus and nitrogen have converted the once-valuable nutrients into poison. About half of the nitrogen contained in fertilizers leaves the fields where they are applied and ends up in the air, soil, and water. And this is the actual problem from where the negative effects of agriculture on the environment starts.
Eutrophication is one of the side effects of deposited phosphorus and nitrogen. These pollutants are also contributing to developing toxic algal-blooms in lakes of China, the US, and more. Land and water accumulated nitrogen is also a gigantic threat to native biodiversity and the health of natural habitats.
Major problems resulting from the use of synthetic fertilizers include:
- Contamination of hydrological cycle
- Soil pollution
- Damage to biodiversity and habitat
Point Source Pollution
Meat shops, dairies, tanneries, fertilizer plants, cattle yards, and many other types of farms are high-risk factors to contaminate catchment areas and discharge pollutants into natural resources. During the past 30 years, the agricultural and industrial sectors have changed a lot and larger farms have emerged. In previous times, farmers used to dispose of the waste in waterways which causes severe water and land pollution. Today, point source pollution only accounts for 3.2%, and 1.8% of the total nitrogen and phosphorus runoff.
Non-Point Source Pollution
Pollution from nonpoint source arises from a variety of activities not associated with a single source, making their regulation difficult. Diffuse pollutants enter the water through ground runoff; animal contamination and leaching.
Problems that can arise from the release of pollutants into agriculture are listed below:
- Soil contamination
- Air pollution
- Residues of pesticides
- Pesticide drift
- Damage to beneficial insects
- Decline in pollination
- Decline in bioremediation
- Development of dead zones due to chemicals runoff
Removing hills and riparian forests for pastures upsurges the total rainfall resulting in more water runoff into the rivers and streams. Forests usually act as the barrier to water runoff and also traps the rainwater and later evaporates it. This reduces the amount of rain reaching the earth.
But due to the conversion of forests into pastures, short grasses and crops fail to intercept the rainwater and water runoff during heavy rains. This weakness the topsoil and its ability to hold plant roots. It also allows the washing away of natural sediments and organic matter into the water systems and decreasing soil fertility.
Removal of Riparian Shading
Vegetation near waterways provides shade and filtration to natural ecosystems. Removing these vegetation decreases the amount of shade and increases the temperature of the water, growth of aquatic weeds and algae, and destroys the habitat of native fauna. The oxygen content in water also decreases with increasing temperature, making survival difficult for natural aquatic life. Riparian planting also acts as valuable filters, removing them will contaminate water with animal faeces and other pollutants.
In the past, the streams have been modified to increase cultivatable areas. Such modifications include diversions, reorientation, and piping of streams. Recently in Taranaki, stream modification, over 700 kilo-meters, project was accomplished. This can have a momentous impact on freshwater reserves, leading to degradation and loss of habitat. It can degrade water quality, change hydrological cycles, and biodiversity.
Use of genetic engineering in agriculture is yet not completed adapted. There are three major objections:
- Environmental and human health risks
- Ethical unacceptability
- Sustainable agriculture incompatibility
Issues by Region
The negative impacts of agriculture on the environment can vary from region to region and due to adapted types of agricultural practices. Some regions based environmental issues are listed below:
- United Kingdom: hedgerow removal
- New Zealand: emission of methane from livestock
- Australia: soil salinization
- Gulf of Mexico: hypoxic zone development due to algae bloom nitrogen fertilization
- Nauru: phosphate mining
Agriculture is an integral part of our life, but modern agricultural practices create numerous negative effects of agriculture on the environment and natural habitats. Clearance of forests for agriculture is destroying the ecosystems and boosting global climate change.