Wednesday, September 10, 2014

Agriculture - Effects of modern methods and options

The widespread use of chemicals in agriculture as fertilizers, pesticides, insecticides and rodenticides without proper technological information have multiplied the hazards to which human beings are exposed. These chemicals spread through the environment and pose a threat to all animals.
Fertilizers are materials that are added to soil to restore and enhance soil fertility to improve the quality and quantity of plant growth.
Fertilizers may be natural or artificial (synthetic). Natural fertilizers are further divided into Organic and inorganic fertilizers. Examples of inorganic fertilizers are Gypsum, Crushed limestone and sulphur rock phosphate while those for organic fertilizers are manure, animal excreta, plant wastes and humus.
Excess fertilizers that are not taken-up by plants, leech into sub-soil water sources and contaminate them. They are non-biodegradable and thus accumulate to reach objectionable levels as they pass through different levels of the food chain.
The main problem with fertilizer use is the contamination of water with nitrates, phosphates and potassium.
Nutrients are lost from agricultural fields through:
-Runoff
-Drainage and
-Attachment to eroded soil particles
Amount of nutrient lost depends on:
-Soil type and organic matter content
-Climate
-Slope
-Depth to groundwater and
-Amount and type of fertilizer and irrigation used
The major nutrients in fertilizers are:
-Nitrogen (N)
-Phosphorus (P) and
-Potassium (K)
Nitrogen is readily lost due to high solubility in nitrate form. Leaching of nitrate from agricultural fields can increase groundwater concentrations to unacceptable levels for drinking water supply
High nitrate levels in drinking water are dangerous to human health
Phosphorus cannot be washed out of soil but can be washed into surface waters together with the soil that is being eroded.
Phosphorus is not dangerous. However, it stimulates the excess growth of algae and this process is called "eutrophication". The algae eventually die and decompose resulting in depletion of dissolved oxygen thereby killing fish.
Potassium does not cause water quality problems. Its solubility is similar to phosphorus i.e., it is similarly bound by soil particles and can be by erosion.
Pesticides:
Qualities of an ideal pesticide:
-It should only kill target pest
-Have no short term or long term effects on non-target organisms
-Should be able to be broken down into harmless compounds in a short time
-Should prevent the development of genetic resistance in target organism
-Save money compared to making no effort to control pest
Since 1945, different types of synthetic organic chemicals have been used as pesticides.
Worldwide, 2.3 million Tonnes of pesticides are used (85% in developing countries.
Synthetic nsecticides are of the following types:
Chlorinated hydrocarbons
Organophosphates
Carbamates
Pyrethroids

DDT and other slowly degradable chlorinated hydrocarbon insecticides were banned in mid 1970s
Organophosphates are more rapidly biodegradable but are water soluble and could possibly contaminate surface and groundwater sources.
Chlorinated hydrocarbons are fat soluble
Farmers apply non-persistent pesticides at regular intervals to ensure effective insect control. The regular use of using non-persistent pesticides is almost as good as using persistent pesticides.
Pyrethrin (from wild chrysanthemum type plants) and Rotenoids (from roots of rain forest legumes) are produced from wild plants and can be effectively used as biological control agents as they are:
-Biodegradable
-Effective in low doses and
-Cause little harm to mammals
ADVANTAGES OF USING PESTICIDES
The following are the benefits of using pesticides:
-pesticides save lives
-they increase food supplies and lower food costs
-they increase profits of farmers
-they work faster and better than alternatives
-safer and more effective products are continuously being developed.
PROBLEMS OF PESTICIDES
Development of genetic resistance
ALTERNATE METHODS OF INSECT CONTROL
Modifying cultivation process
-crop rotation
-planting rows of hedges or trees in and around crop fields
-adjusting planting times
-destroy diseased or infected plants
-growing crops in areas where their major pests do not exist
-using plant diversity to control pests by adopting:
                         intercropping
                         agro-forestry and
                         polyculture
-artificial selection, cross breeding and genetic engineering varieties of plants and animals that are genetically resistant to certain pest insets, fungi and diseases.
-biological pest control against various natural parasites and pathogens can be introduced to control the populations of specific pests.
ORGANIC AGRICULTURE:
Organic agriculture is defined as an ecological production management system that promotes and enhances biodiversity, biological cycles and soil biological activity. It is based on minimal use of off-farm inputs and on management practices that restore, maintain and enhance ecological harmony.

EFFECTS OF MODERN AGRICULTURE
Agriculture has been a practice in use for hundreds of years. It provides countless people with sustenance and livelihood all over the world. However, modern practices in agriculture have led to several damaging effects on the environment listed below:
1.Agriculture increases carbon dioxide levels making it one of the main sources of carbon dioxide emissions for decades. This in-turn aggravates the problem of global warming and consequent sea level rise.
2.Animal waste from farms contains harmful pathogens known to cause disease and infection. By getting into soil and water systems they create irreversible damage to land and pose health risks towards humans. These problems lead both directly and indirectly to these health risks, and may causes disorders such as hepatitis and meningitis.
3.Fertilizers also put forth several complications. They contain harmful elements such as nitrogen and phosphates, both of which negatively affect air and water quality. Its use causes the release of ammonia, nitrogen runoff and eutrophication, all of which have negative effects on the environment.
4.Impacts also include increased water or wind erosion, depleted groundwater supplies in irrigated areas,
5.Modern agriculture converts an ever-increasing portion of the earth's land surface to monoculture. As a result, the genetic and ecological diversity of the planet erodes. The conversion of diverse natural ecosystems to new agricultural lands and the narrowing of the genetic diversity of crops contribute to this erosion.
6.In addition to adding pollutants to water, soil and air, modern agriculture practices can cause soil disturbance by using heavy machines and tilling equipment. This, in turn, creates soil erosion and degrades the quality of surrounding farmland.
7.A number of "ecological diseases" have been associated with the intensification of food production. They may be grouped into two categories: diseases of the ecotope, which include erosion, loss of soil fertility, depletion of nutrient reserves, salinization and alkalinization, pollution of water systems, loss of fertile croplands to urban development, and diseases of the biocoenosis, which include loss of crop, wild plant, and animal genetic resources, elimination of natural enemies, pest resurgence and genetic resistance to pesticides, chemical contamination, and destruction of natural control mechanisms.

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