avoiding soil loss

preventing soil erosion

Soil is a natural resource that is vitally important for sustaining natural habitats and for growing food. Although soil is a renewable resource, it is renewed slowly, taking hundreds or thousands of years for a good fertile soil to develop. Organic material can be added to soil to help increase its fertility. Most of the best land for farming is already being cultivated. With human populations continuing to grow, it is extremely important to protect our soil resources. Agricultural practices such as rotating crops, alternating the types of crops planted in each row, and planting nutrient-rich cover crops all help to keep soil more fertile as it is used season after season. Planting trees as windbreaks, plowing along contours of the field, or building terraces into steeper slopes will all help to hold soil in place (Figure 1.3). No-till or low-tillage farming helps to keep soil in place by disturbing the ground as little as possible when planting. Steep slopes can be terraced to make level planting areas and decrease surface water runoff and erosion. The rate of topsoil loss in the United States and other developed countries has decreased recently as better farming practices have been adopted. Unfortunately, in developing nations, soil is often not protected. Table 1.1 shows some steps that we can take to prevent erosion. Some are things that can be done by farmers or developers. Others are things that individual homeowners or community members can implement locally. Source of Erosion Strategies for Prevention Leave leaf litter on the ground in the winter. Grow cover crops, special crops grown in the winter to cover the soil. Plant tall trees around fields to buffer the effects of wind. Drive tractors as little as possible. Use drip irrigation that puts small amounts of water in the ground frequently. Avoid watering crops with sprinklers that make big water drops on the ground. Keep fields as flat as possible to avoid soil erod- ing down hill. Grazing Animals Move animals throughout the year, so they dont consume all the vegetation in one spot. Keep animals away from stream banks, where hills are especially prone to erosion. Logging and Mining Reduce the amount of land that is logged and mined. Reduce the number of roads that are built to access logging areas. Avoid logging and mining on steep lands. Cut only small areas at one time and quickly replant logged areas with new seedlings. Development Reduce the amount of land area that is developed into urban areas, parking lots, etc. Keep as much green space in cities as possible, such as parks or strips where plants can grow. Invest in and use new technologies for parking lots that make them permeable to water in order to reduce runoff of water. Recreational Activities Avoid using off-road vehicles on hilly lands. Stay on designated trails. Avoid building on steep hills. Grade surrounding land to distribute water rather than collecting it in one place. Where water collects, drain to creeks and rivers. Landscape with plants that minimize erosion. Click image to the left or use the URL below. URL:

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soil erosion

Bad farming practices and a return to normal rainfall levels after an unusually wet period led to the Dust Bowl. In some regions more than 75% of the topsoil blew away. This is the most extreme example of soil erosion the United States has ever seen. Still, in many areas of the world, the rate of soil erosion is many times greater than the rate at which it is forming. Drought, insect plagues, or outbreaks of disease are natural cycles of events that can negatively impact ecosystems and the soil, but there are also many ways in which humans neglect or abuse this important resource. Soils can also be contaminated if too much salt accumulates in the soil or where pollutants sink into the ground. One harmful practice is removing the vegetation that helps to hold soil in place. Sometimes just walking or riding your bike over the same place will kill the grass that normally grows there. Land is also deliberately cleared or deforested for wood. The loose soils then may be carried away by wind or running water. A farmer and his sons walk through a dust storm in Cimarron County, Oklahoma in 1936. Click image to the left or use the URL below. URL:

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organic material

Adding organic material to the soil in the form of plant or animal waste, such as compost or manure, increases the fertility of the soil and improves its ability to hold on to water and nutrients (Figure 1.2). Inorganic fertilizer can also temporarily increase the fertility of a soil and may be less expensive or time consuming, but it does not provide the same long-term improvements as organic materials.

soil conservation

Soil is only a renewable resource if it is carefully managed. There are many practices that can protect and preserve soil resources.

instructional diagrams

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questions

how does terracing prevent soil erosion?

a) keeps soil from moving very far downhill

b) slows the speed of water

c) removes vegetation, which slows erosion

-->  d) a & b

developed nations have improved farming practices to protect topsoil.

-->  a) true

b) false

which is not an example of an agricultural practice that helps prevent soil erosion?

a) crop rotation

-->  b) monoculture crops

c) alternating the types of crops planted in each row

d) planting nutrient-rich cover crops

soil is

a) a renewable resource that takes a short amount of time to develop.

-->  b) a renewable resource, but it takes a really long amount of time to develop.

c) a nonrenewable resource.

d) not a resource.

how can loggers reduce the amount of soil erosion?

a) avoid logging on steep lands

b) cut only small areas at one time

c) replant logged areas with new seedlings

-->  d) all of the above

which of the following will not damage soils?

a) salt accumulation.

-->  b) returning a landscape to its native vegetation.

c) exposing soil to the elements.

d) drought.

the single cause of the dust bowl was

a) bad farming practices.

b) a drought.

c) a return to normal rainfall patterns.

-->  d) there was no single cause of the dust bowl.

the best way to fertilize soil is to

a) use inorganic fertilizer, which is less expensive.

b) use compost, which protects the soil from holding too much water.

-->  c) use manure, which adds back nutrients.

d) use nitrogen and phosphorous, which provides long-term improvements in soil.

to reduce erosion in cities,

-->  a) include green spaces because plants absorb water.

b) cover the region with as much concrete as possible to protect the soil beneath.

c) keep pets on sidewalks so they dont trample the grass.

d) none of these.

off-road vehicles and people hiking off of trails can cause significant erosion.

-->  a) true

b) false

diagram questions

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