Conservation Of Soil Essay

[Sinikka Curz]

SoilConservation is a combination of practices used to protect the soil from degradation. First and foremost, soil conservation involves treating the soil as a living ecosystem. This means returning organic matter to the soil on a continual basis.

Soil conservation can be compared to preventive maintenance on a car. Changing the oil and filter, and checking the hoses and spark plugs regularly will prevent major repairs or engine failure later. Similarly, practicing conservation now will preserve the quality of the soil for continued use.

Soil conservation is a "combination" of practices used to protect the soil from degradation. First and foremost, soil conservation involves treating the soil as a living ecosystem, and recognizing that all the organisms that make the soil their home, play important roles in producing a fertile healthy environment. They are responsible for breaking down organic matter, releasing nutrients, and opening up spaces for the circulation of air and water.

Because most organisms in the soil depend on dead plant and animal matter for their food and energy, soil conservation requires that organic matter be returned to the soil on a continual basis. Organic matter is what provides good soil structure and water holding capacity, promotes water infiltration, and protects the soil from erosion and compaction.

Soil conservation is an active ongoing process throughout which the practitioner must maintain his/her commitment. The first step is to obtain a good basic knowledge of the land resource. This means knowing where the soil is most permeable and susceptible to groundwater contamination from excess pesticides; or where the land is most susceptible to water erosion because of a combination of slope and soil texture. Without this understanding, it is impossible to plan an appropriate conservation strategy.

The next steps are identifying or predicting problem areas, choosing and implementing soil conservation techniques, and maintaining control structures. The final step is to continually monitor the effectiveness of the plan and make changes if and when necessary.

In conservation tillage, at least 20 to 30 percent of the soil surface is covered in the previous year's crop residue after planting. The residue reduces wind velocity at the soil surface and breaks the impact of raindrops. Root systems hold the soil in place. If practiced across a slope, rows of stubble act as small dams to slow water as it runs down hill.

Another aspect of conservation tillage is the choice of machinery used. The traditional moldboard plow tends to overturn and throw the soil leaving it bare and exposed to erosion. Chisel plows however, leave 30 to 50 percent of the soil surface covered with residue.

Timing is also important. For most soil types, it is better to till a field in the spring after the major erosive force of spring melt has passed. (Clay soils however, respond best to fall tillage). Soil should not be tilled and traveled on when it is wet. This practice is the leading cause of soil compaction.

Aside from erosion control, the other advantages of conservation tillage are increased water infiltration, a greater addition of organic matter to the soil, and savings of fuel and time for the farmer. Conservation tillage also enhances wildlife habitat for soil organisms, birds and small animals like field mice and snakes.

Contour farming involves tilling and planting along the contour, rather than up and down the slope. The furrows and rows of plants act as dams which slow down the flow of water moving down the slope. Unless some type of contour farming is used, particularly on long slopes, serious field erosion can result.

Strip cropping involves alternating strips of small grain (e.g. rye) or forage crops (e.g. clover) with row crops like corn. It is used to control erosion by reducing the velocity of wind and water. The forage and cereal grain rows tend to trap sediment that may otherwise end up in watercourses.

Strip cropping is most effective in controlling erosion on a slope when it is placed along the contour of the land. To control wind erosion, it works best if the strips are placed at right angles to the direction of the prevailing winds.

A windbreak or shelterbelt is a vegetation barrier designed to reduce or eliminate the velocity of the wind and hence reduce wind erosion. (Windbreaks are also used for snow control and to provide shelter for buildings and livestock).

Windbreaks are generally planted on the west, southwest, or northwest boundary of a field to provide protection from prevailing winds. The protection is maximized downwind of the barrier, where the wind speed is significantly reduced for a distance of 15 to 20 times the height of the trees. The windward side of the break receives protection for 3 to 5 times the total height.

The benefits of both windbreaks and shelter belts extend far beyond just erosion control. Crop quality and livestock performance are improved due to less abrasion from blowing soil. Tree and shrub rows significantly increase the aesthetics of the landscape which is proven by higher land values. They also trap snow in the winter and thus provide a higher moisture content for the growing season.

A major benefit of windbreaks is their enhancement of wildlife habitat. They provide places to roost, nest and seek cover from predators from harsh winter climate. The damage some animals do to crops is balanced by the role others play in controlling insects or unwanted rodents like mice.

Crop Rotation is an alternative to planting a field in the same crop year after year (referred to as continuous mono-shelterbeltsculture cropping). Instead, the main crop is rotated, ideally with cereal crops like winter wheat or forages such as clover and alfalfa.

Crop rotation provides several benefits. Rotation reduces the risk of insect and disease problems, thus decreasing a pesticide dependency. Because the crop is changed each year, pests do not have enough time to become established in damaging numbers.

Forage crops or legumes such as clover and alfalfa are often used as green fertilizers or plow-down crops, meaning they are planted and later mixed in with the soil as a natural fertilizer and soil builder. Legumes have the special ability to take in atmospheric nitrogen and convert it to forms usable by other plants. (Atmospheric nitrogen is not in a form available to most plants). For this reason they are also referred to as nitrogen fixing plants.

When used as a green fertilizer, legumes return a significant amount of organic matter to the soil. Their deep roots create tunnels for air and water to enter the soil. All these characteristics in turn guard the surface against water and wind erosion.

Cover crops are crops planted to reduce the impact of wind and water on bare soil. They absorb the impact of rain, reduce the speed of runoff, hold the soil in place, and encourage greater infiltration; and hence less runoff.

Sweet clover, alfalfa, rye, and winter wheat are common cover crops. They are planted on areas susceptible to erosion like steep slopes; stream and river banks, grassed waterways or around wells to protect ground water supplies from contamination. Winter wheat or rye are often planted to provide cover over the winter and 95 to 100 percent erosion control during the spring runoff.

Intercropping involves mixing plants in a field - for example planting legumes between rows of corn or soybean. This technique may be used by a farmer who cannot afford to take his or her entire crop of corn out of production.

A buffer strip is an area of land adjacent to a watercourse that is vegetated with grasses or bushes. The plant cover filters sediment out of runoff, holds the soil in place and prevents washout, slumping, and reductions in water quality due to siltation. Buffer strips are generally 2 to 5 meters wide. (The width varies according to soil texture and slope). They should be protected from tillage, machinery and cattle access to work effectively.

Aside from erosion control, buffer strips provide excellent wildlife habitat for small animals and insects. If forested, they can improve stream habitat by shading the water and making the environment more suitable to fish species like trout. The leaves that fall into the water provide organic matter for small stream invertebrates which are in turn food for larger stream animals like crayfish. Stream-side forests are extremely productive habitats for wildlife, and like shelter belts, they also improve the aesthetic quality of the environment.

A grassed waterway is a permanently vegetated saucer-shaped channel designed to carry surface runoff across land without causing erosion. It is commonly used where gully or rill erosion is taking place due to the concentrated flow of water overland. The grass slows the flow of water and protects the soil from erosion. The water is carried safely to a stable outlet such as a drainage ditch or stream.

A terrace is a constructed earthen ridge with a water channel along the upper side. There are several design options, but commonly both the ridge and channel are permanently grassed. Terraces are designed to intercept runoff on a slope, and reduce its erosive action on the soil down the slope. Water is channeled at a slower speed, along the vegetated channel to a safe, stable outlet such as a grassed waterway or standpipe or drop inlet.

A drop inlet consists of a vertical intake pipe and a horizontal underground pipe. The water enters the vertical pipe at ground surface, and falls below where it is guided safely through a large concrete metal or plastic pipe into a stream or ditch.

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