14-4 Soil Conservation
How Can Conservation Tillage Reduce Soil Erosion? Do Not Disturb the Soil
Soil conservation involves using ways to reduce soil erosion and restore soil fertility:
In conventional-tillage farming, farmers plow the land and then break up and smooth the soil to make a planting surface.
With minimum-tillage farming, the soil is not disturbed over the winter. Then, at planting time, special tillers break up and loosen the subsurface soil without turning over the topsoil, previous crop residues, or any cover vegetation.
In no-till farming, special planting machines inject seeds, fertilizers, and weed killers (herbicides) into thin slits made in the unplowed soil and then smooth over the cut.
What Other Methods Can Reduce Soil Erosion? Several Tried and True Methods
The following are some methods farmers have used to reduce soil erosion:
Terracing can reduce soil erosion on steep slopes by converting the land into a series of broad, nearly level terraces that run across the land contour. This retains water for crops at each level and reduces soil erosion by controlling runoff.
Contour farming involves plowing and planting crops in rows across the slope of the land rather than up and down. Each row acts as a small dam to help hold soil and to slow water runoff.
Farmers also use strip cropping to reduce soil erosion. It involves planting alternating strips of a row crop (such as corn or cotton) and another crop that completely covers the soil (such as grass or a grass and legume mixture). The cover crop traps soil that erodes from the row crop, catches and reduces water runoff, and helps prevent the spread of pests and plant diseases.
Another method for slowing erosion is alley cropping or agroforestry, in which several crops are planted together in strips or alleys between trees and shrubs that decrease the effects of wind.
Some farmers establish windbreaks, or shelter- belts, of trees to reduce wind erosion, help retain soil moisture, supply wood for fuel, and provide habitats for birds, pest-eating and pollinating insects, and other animals.
How Can We Maintain and Restore Soil Fertility? Conservation and Fertilizers
The best way to maintain soil fertility is through soil conservation. The next best thing to do is to restore some of the plant nutrients that have been washed, blown, or leached out of soil or removed by repeated crop harvesting. Fertilizers can partially restore lost plant nutrients. Farmers can use organic fertilizer from plant and animal materials or commercial inorganic fertilizer produced from various minerals.
There are several types of organic fertilizer.
One is animal manure: the dung and urine of cattle, horses, poultry, and other farm animals. It improves soil structure, adds organic nitrogen, and stimulates beneficial soil bacteria and fungi.
A second type of organic fertilizer called green manure consists of freshly cut or growing green vegetation plowed into the soil to increase the organic matter and humus available to the next crop.
A third type is compost, produced when micro- organisms in soil break down organic matter such as leaves, food wastes, paper, and wood in the presence of oxygen.
Can Inorganic Fertilizers Save the Soil? A Partial Solution
Many farmers (especially in developed countries) rely on commercial inorganic fertilizers. The active ingredients typically are inorganic compounds containing nitrogen, phosphorus, and potassium. Other plant nutrients may also be present in low or trace amounts. These fertilizers account for about one-fourth of the world’s crop yield.