What is the key concept for this section? What is soil conservation? Describe si

Question

What is the key concept for this section? What is soil

conservation? Describe six ways to reduce topsoil

erosion. Distinguish among organic fertilizer, synthetic inorganic fertilizer, animal manure,

green manure, and compost. How does crop rotation help restore topsoil fertility? What are some

ways to prevent and some ways to clean up soil salinization? How can we reduce desertification? Describe three ways to make aquaculture more

sustainable. What are some ways to make meat production and consumption more sustainable? Summarize three important components of a more

sustainable food production system. List the advantages of relying more on organic polyculture

and perennial crops. What are five strategies that

could help farmers and consumers to shift to more

sustainable food production? What are three important ways in which individual consumers can help to

promote more sustainable food production?

Explanation / Answer

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.

In addition to preserving soil life and organic matter, the other principles of soil conservation are to:

manage surface runoff,
protect bare exposed soil surfaces, and highly susceptible sites (e.g. steep slopes), and
protect downstream watercourses from sedimentation and pollution.

Soil Conservation Techniques

Conservation Tillage

Conservation tillage consists of a variety of practices used in agriculture to reduce wind and water erosion. The main principles are:

a) to keep bare soil protected at ll time of the year either with living vegetation, or with residue from the previous crop; and

b) to minimize the number of times the field is tilled.

Bare soil is highly susceptible to erosion. Excess tillage destroys soil structure and organic matter.

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.

No-till farming involves planting seeds into the residue of the previous crop, with no tillage between harvest. No till leaves 60 to 70 percent of a field covered with crop residue.

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

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.

Contour farming also uses less fuel and power for tractors.

Strip Cropping

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.

Another benefit of strip cropping is the organic matter added from the forage or cereal crop rows.

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