AGRICULTURE AND ITS EFFECT ON THE ENVIRONMENT

Introduction

Agricultural development is aimed at achieving self- sufficiency in food production to the ever increasing human population. However,  this has resulted in continuous environmental degradation, particularly of soil, vegetation and water resources. Soil organic matter levels are declining at an alarming rate because the use of chemical inputs is intensifying. Newly introduced crops and the chemicals .This has been accelerated both by increased fertiliser application and use of irrigation resulting in water contamination by nitrate and phosphate and changes in the ground water table. With  over 80% of the geographic area already under cultivation, the scope for increased productivity lies in further intensification which is crucially dependent on more energy-intensive inputs. Declining nutrient-use efficiency, physical and chemical degradation of soil, and inefficient water use have been limiting crop productivity, whilst the use of monocultures, mechanisation and an excessive reliance on chemical plant protection have reduced crop, plant and animal diversity in recent years. About 60% of the geographical area faces soil degradation (waterlogging, salinity and alkalinity) which threatens the region’s food security in the future. Since 1985, the water table has risen more than 1 m annually, and patches of salinity have started to appear at the farm level. The situation is worse in higher rainfall areas where waterlogging follows shortly after the rains. Apart from affecting agricultural crops, a high water table causes floods even following slight rains due to the reduced storage capacity of the soil. Such ecological impacts are motivating farmers to reduce fertiliser and pesticides use. This has led to an increased investment in alternative technology and products including an interest in Integrated Pest Management. The paper discusses major physical, hydrological, chemical and biological constraints relating to soil and water caused by agricultural development and recommends  on environmental sustainability.

  Environmental effects of agricultural development

1.Deforestation

Agriculture is a major land use. Statistics show that around 50% of the world's habitable land has already been converted to farming land. The overall farmland is estimated to cover about 38% of the world's land area.
One of the causes of deforestation is to clear land for pasture or crops. In 2000 the United Nations Food and Agriculture Organization (FAO) found that "the role of population dynamics in a local setting may vary from decisive to negligible," and that deforestation can result from "a combination of population pressure and stagnating economic, social and technologic climate change.

 It is predicted that in developing countries, a further 120 million hectares of natural habitats will be converted to farmland to meet demand for food by 2050. This will include land with high biodiversity value.

 Agricultural ecosystems provide important habitats for many wild plant and animal species. This is especially the case for traditional farming areas that cultivate diverse species. Recent examples include the conversion of lowland rainforests in Indonesia to oil palm plantations, and of large areas of the Amazon rainforest and Brazilian savanna to soybean and cattle farms.
This ongoing habitat loss threatens entire ecosystems as well as many species.Due to the habitat loss, many species have become extinct and more are expected to if nothing is done. Expanding oil palm plantations in Indonesia and Malaysia, for example, pose the most significant threats to endangered species like megafauna including Asian elephant, Sumatran rhinoceros, and tigers.

In addition to the loss of biodiversity,deforestation which is as a result of agricultural development has  also led to desertification of so ecological  zones.This is because trees play a key role in the hydrological cycle.Once the trees are eliminated from the system,the rain patterns are going  to decrease or even diminish bringing about desertification.

Most of the cleared natural habitats for agricultural purposes are always meant to be for large  intensive monocultures.This type of practice leads to decline in soil fertility since land is not given time as opposed to the traditional farming methods that allowed land to rest.Therfore this results in loss of soil fertility and therefore biodiversity is decreased

2. Climate change.

Climate change cannot be isolated from agricultural processes; both are greatly interrelated and take place on a global scale.

Development in agriculture has been shown to produce significant effects on climate change. This has happened primarily through the production and emission of gases. Farming practices in agriculture are significant contributors to the build-up of green house gases such as carbon dioxide, methane, and oxides. Most industries which pollute the environment are related to agricultural development. These industries include fertilizer factories, sugar factories, oil and pulp mills, textile mills and tanneries.

© WWF-Canon / Mauri RAUTKARI

Emissions and effluents from these industrial complexes are already causing some harm to man, animals and environment in general. Land clearance to give room for more agricultural land has adversely affected the environment. This has led  to the alteration of the Earth's land cover, which can change its ability to absorb or reflect heat and light, thus contributing to forcing. In addition deforestation has brought about imbalances in the levels of concentration of carbon dioxide which among other gases such as methane and nitrous oxides brings about global warming. Global warming therefore is projected to have significant impacts on conditions affecting agriculture, including temperature, precipitation and glacial run-off. These conditions determine the carrying capacity of the biosphere to produce enough food for the human population and domesticated animals. Rising carbon dioxide levels would also have effects, both detrimental and beneficial, on crop yields. The overall effect of climate change on agriculture will depend on the balance of these effects. Assessment of the effects of global climate changes on agriculture might help to properly anticipate and adapt farming to maximize agricultural production.

3. Genetic engineering

Traditional biotechnology has been abandoned and replaced by genetic engineering. In genetic engineering, biotechnology in agricultural production is the order of the day. This is the application of scientific techniques to modify and improve plants animals and microorganisms to enhance their value.

Advances in the field of molecular biology were achieved in 1970s.This has provided scientists with the ability to manipulate DNA-the chemical building blocks that specify the characteristics of living organisms at molecular level. It also allows the transfer of DNA between more distantly related organisms than was possible with traditional breeding technology. Today this technology has reached a stage where scientist can take on one or more specific genes from nearly any organisms including plants, animals, bacteria and viruses and introduce those genes into another organism. This technology is referred to as genetic engineering and the organisms are known as genetically modified or transgenic organisms. Everything in life has its benefits and risks, and genetic engineering is no exception. Much has been said about potential risks of genetic engineering technology, but so far there is little evidence from scientific studies that these risks are real. Transgenic organisms can offer a range of benefits above and beyond those that emerged from innovations in traditional agricultural biotechnology. Following are a few examples of benefits resulting from applying currently available genetic engineering techniques to agricultural biotechnology

When genetic engineering results in reduced pesticide dependence, we have less pesticide residues on foods, we reduce pesticide leaching into groundwater, and we minimize farm worker exposure to hazardous products. With Bt cotton’s resistance to three major pests, the transgenic variety now represents half of the U.S. cotton crop and has thereby reduced total world insecticide use by 15 percent! Also, according to the U.S. Food and Drug Administration (FDA), “increases in adoption of herbicide-tolerant soybeans were associated with small increases in yields and variable profits but significant decreases in herbicide use”

Biotechnology has helped to increase crop productivity by introducing such qualities as disease resistance and increased drought tolerance to the crops. Farmers use crop-protection technologies because they provide cost-effective solutions to pest problems which, if left uncontrolled, would severely lower yields. As mentioned above, crops such as corn, cotton, and potato have been successfully transformed through genetic engineering to make a protein that kills certain insects when they feed on the plants. The protein is from the soil bacterium Bacillus thuringiensis, which has been used for decades as the active ingredient of some “natural” insecticides.

However as mentioned earlier,there are possible environmental risk associated with this type of technology. Some consumers and environmentalists feel that inadequate effort has been made to understand the dangers in the use of transgenic crops, including their potential long-term impacts. Some consumer-advocate and environmental groups have demanded the abandonment of genetic engineering research and development. There is a belief among some opponents of genetic engineering technology that transgenic crops might crosspollinate with related weeds, possibly resulting in “superweeds” that become more difficult to control. One concern is that pollen transfer from glyphosate-resistant crops to related weeds can confer resistance to glyphosate. While the chance of this happening, although extremely small, is not inconceivable, resistance to a specific herbicide does not mean that the plant is resistant to other herbicides, so affected weeds could still be controlled with other products.

 Some people are worried that genetic engineering could conceivably improve a plant’s ability to “escape” into the wild and produce ecological imbalances or disasters. Most crop plants have significant limitations in their growth and seed dispersal habits that prevent them from surviving long without constant nurture by humans, and they are thus unlikely to thrive in the wild as weeds.  

Some environmentalists maintain that once transgenic crops have been released into the environment, they could have unforeseen and undesirable effects. Although transgenic crops are rigorously tested before being made commercially available, not every potential impact can be foreseen. Bt corn, for instance, produces a very specific pesticide intended to kill only pests that feed on the corn. In 1999, however, researchers at Cornell University found that pollen from Bt corn could kill caterpillars of the harmless Monarch butterfly. When they fed Monarch caterpillars milkweed dusted with Bt corn pollen in the laboratory, half of the larvae died. But follow-up field studies showed that under real-life conditions Monarch butterfly caterpillars are highly unlikely to come into contact with pollen from Bt corn that has drifted onto milkweed leaves—or to eat enough of it to harm them.

Another concern related to the potential impact of agricultural biotechnology on the environment involves the question of whether insect pests could develop resistance to crop-protection features of transgenic crops.

4. Irrigation Farming:

Agriculture is the greatest user of water globally, the agricultural sector consumes about 70% of the planet's accessible freshwater more than twice that of industry which is esimated at23% and dwarfing municipal use 8%. Excessive water use for agriculture is leaving rivers, lakes and underground water sources dry. Many big food producing countries like the US, China, India, Pakistan, Australia and Spain have reached, or are close to reaching, their renewable water resource limits.Agriculture wastes about 60% or 1,500 trillion of the2,500 trillion litres of water it uses every year. The major causes of improper water utilization in irrigation farming include the following;

Ø  Poorly maintained irrigation pipes that allows water to leak hence wasteges during application.

Ø  Irrigation system employed.

Ø  Poor choice of crops.

Irrigation can lead to a nmumber of environmental  problems if it is not done in a proper and sustainable way.such problems include:

v  Depletion of underground aquifers through overdrafting.

v  Underirrigation gives poor soil salinity control which leads to increased soil salinity with consequent build up of toxic salts on soil surface in areas with high evaporation. This requires either leaching to remove these salts and a method of drainage to carry the salts away.

v  Overirrigation because of poor distribution uniformity or management wastes water, chemicals, and may lead to water pollution.

v  Deep drainage (from over-irrigation) may result in rising water tables which in some instances will lead to problems of irrigation salinity requiring watertable control by some form of subsurface land drainage.

v  Irrigation with saline or high-sodium water may damage soil structure.

v  Runoff causing surface water and groundwater-aquifer hydrologic cycle water pollution.

v  The problem is made worse by misdirected subsidies, low public and political awareness of the crisis, and weak environmental legislation.

v  Excessive irrigation can also increase soil salinity and wash pollutants and sediment into rivers – causing damage to freshwater ecosystems and species as well as those further downstream, including coral reefs and coastal fish breeding grounds.

5. Pollutants.

Modern agriculture require intensive use of agricultural chemicals geared towards maximum production. Most dangerous chemicals that are used in large quantities today are  mostly for agriculture. These chemicals include fertilizers, insecticides, fungicides, herbicides and other pesticides.

In modern agricultultural practices,fertilizers are added to the soil because they help plants to grow and produce maximum yields. However the environmental problems associated with fertilizers application come about if they are washed out of the soil by the rain and leached into the ground water, into lakes or streams, or into the lagoon where they contribute to pollution. The fertilizers in the water encourage algae(algal bloom) and other plants to grow, and these may become so thick that they start to rot and smell. They may also crowd out or shade out other valuable forms of life like corals. Nitrate fertilizers are also dangerous if they get into drinking water, because they may be turned into nitrites which can cause cancer.

Pesticides are by their very nature poisons for at least some kinds of life, often including people.

Agriculture is the leading source of pollution in many countries.

© Michel Gunther / WWF-Canon

 Pesticides can hurt the environment or poison people in many ways. They may be used without following the instructions very carefully, so that too much is used, or at the wrong time. They may be absorbed by the people who apply the pesticides, especially in the tropics where people do not know much about pesticides and do not like or even have protective clothing. They may be washed off the crop or field by the rain, or blown into villages or into the forest by the wind. They may be applied too close to harvest time and thus still be on the food when it is harvested and eaten. They may not be used the way they were intended (such as for poisoning fish), or be washed into water supplies when users wash their equipment carelessly. They may be eaten accidentally by children thinking they are something good, or by people who use pesticide containers for food or drink. They may be taken intentionally by people who want to commit suicide (if it is a poison with no known cure, even if they change their mind they still die a horrible death). They may spill or leak while they are being transported or while they are in storage.

Once they get into the environment where they are not wanted, they can be a great danger to people and to many useful forms of life. Pesticides should thus only be used when absolutely necessary, and with the greatest care. The increasing use of dangerous chemicals for agricultural development projects can thus have serious impacts on the island environment either directly through the project or indirectly through the risks associated with simply having such chemicals on the island.

 

 

 

 

6.Soil degradation

The soil is an essential agricultural resource and it should be used sustainably. The kinds of agricultural development proposed must be adapted to the requirements for soil conservation at the site to be developed. The risk of soil loss is often greater with large development projects, which attempt to achieve economies of scale through large cleared areas and the use of machines.

Farming operations that are done on large scale basis usually involve mechanisation.Large machines are used in these operations and they destroy the soil structure making them vulnerable to soil degradation.

© Michel Gunther / WWF-Canon

While these technologies are highly successful in the more temperate conditions of the developed countries, they are not always as appropriate to tropical conditions with fragile soils and frequent problems of erosion. In some cases, the use of poorly chosen machinery or techniques has badly damaged the soil structure.

The economic requirement for a continuing return on investments may not permit the periods of fallow which allowed island soils to regenerate. While a decline in fertility can be made up with chemical fertilizers, the rapid loss of humus in the tropics is more difficult to replace, and the soil structure and its ability to hold water may deteriorate. Techniques like composting and mulching which restore organic matter to the soil are seldom practised on a large scale.

Agricultural development projects need to be adapted to these constraints. Crop rotations and the use of legume crops can help to maintain the soil. It may be necessary to use mixed plantings of more than one crop, to use cover plants to protect the soil from heavy rain, or to use windbreaks and other protective plantings around the crop. The new techniques of agro-forestry in which trees and food or crop plants are mixed are showing promise in tropical areas and may well be appropriate.

7. Waste

Agricultural waste is any substance or object from premises used for agriculture or horticulture, which the holder discards, intends to discard or is required to discard. It is waste specifically generated by agricultural activities.

For example, waste which came from a farm shop or a vegetable packing plant would not be agricultural waste.

Some examples of agricultural waste are:

Ø  empty pesticide containers;

Ø  old silage wrap;

Ø  out of date medicines and wormers;

Ø  used tyres;

Ø  Surplus milk.

Since 2006, agricultural waste has been subject to the same controls that have applied to other sectors for many years. On 15 May 2006, uncontrolled burning or tipping of waste on farms became illegal.

Plasticulture, the use of plastic materials in agriculture, raises problems around how to carry out the recycling of agricultural plastics.

 8.Land lost to desertification

Desertification is the process of making or becoming a desert-a drybarren often sand- covered area of land,characteristically desolate,waterless and without vegetation.

Increasing human pressure on the land can lead to desertification through such activities as over-cultivation ,overgrazing, deforestation and poor water management

On top of habitat loss due to clearing, unsustainable agricultural practices are seeing 12 million hectares of land lost each year to desertification.

9.Other effects

Agricultural development can bring with it other risks to the  environment. The large quantities of seeds imported for some projects may contain a few weed seeds. Even one or two unwanted seeds can introduce a noxious weed that may become a serious problem when released in the ecosystem with few competitors or enemies.

Seeds or planting stock that are not carefully inspected and subject to strict quarantine requirements may also introduce pests or diseases previously unknown to  the area and which can ruin its agriculture.

Even some supposedly useful animals and plants introduced for agricultural purposes have turned into pests in the given area with serious effects on native species and even on agriculture itself. Guava, myna birds, cane toads and mongooses are obvious examples.

 Conclusion
Our environment is very precious, and many natural resources are non-renewable. In the process of achieving higher levels of growth and income particularly in agriculture, man has played havoc with Nature's balance. Sustainable growth and sustainable development, based on protection and conservation of the environment, are the need of the hour.
The very existence of the human race will be threatened by natural disasters, if environmental damage crosses a critical limit. This is a clear warning to all of us to pay attention to these environmental threats and adopt appropriate agricultural measures to prevent further disasters.

It should be clear from all of the above that agricultural development projects require extremely careful planning if they are not to have unexpected and often serious effects on people and the environment.

Recommendations
The governments need to formulate a careful policies on their agricultural practices.  While making advances in agricultural technologies, sustainability should not be overlooked and while ensuring reasonable agricultural prosperity at present, we should not presume to preside over the future.

• Water Resource Management: Community wells may be dug instead of individual wells so that water will be granted on a need-based . Rainwater harvesting is another viable option that must be explored, as it is virtually a free resource.
• Afforestation: In order to upgrade the environment, plants have to be grown on a top priority basis. These plants must be selected not only on the consideration of quick growth, but also in terms of their effects on agricultural development and environment. Strict measures have to be taken to check further deforestation.
• Suitable Input Mix: Seeds, fertilizers, pesticides and agricultural implements have to be combined in such a way so as to meet the present challenges, and yet also ensure future stability.
• Suitable Cropping Pattern: By adopting appropriate policy measures, policy makers should give the desired direction to efforts to maintain environmental balance.

According to EMCA 1999 section 58, all development projects, must udergo Environmental Impact Assessments.

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8.       W.M Adams.1990 Green Development; Environment and sustainability in 3rd World