Calculating Soil LossCalculating Soil Loss

Soil Erosion and Land Soil Erosion and Land Management Management

Next Generation Science/Common Core Standards Addressed!Next Generation Science/Common Core Standards Addressed!

CCSS.ELA-Literacy.RST.9-10.3 Follow precisely a complex multistep CCSS.ELA-Literacy.RST.9-10.3 Follow precisely a complex multistep procedure when carrying out experiments, taking measurements, or procedure when carrying out experiments, taking measurements, or performing technical tasks, attending to special cases or exceptions defined performing technical tasks, attending to special cases or exceptions defined in the text.in the text.

CCSS.ELA-Literacy.RST.9-10.9 Compare and contrast findings presented CCSS.ELA-Literacy.RST.9-10.9 Compare and contrast findings presented in a text to those from other sources (including their own experiments), in a text to those from other sources (including their own experiments), noting when the findings support or contradict previous explanations or noting when the findings support or contradict previous explanations or accountsaccounts

CCSS.Math.Content.HSN-Q.A.3 Choose a level of accuracy appropriate to CCSS.Math.Content.HSN-Q.A.3 Choose a level of accuracy appropriate to limitations on measurement when reporting quantitieslimitations on measurement when reporting quantities

Work!Work!

1. Describe the soil erosion process.1. Describe the soil erosion process. 2. Identify the various types of soil erosion.2. Identify the various types of soil erosion. 3. Estimate the amount of soil loss from 3. Estimate the amount of soil loss from

water erosion.water erosion. 4. Discuss how to control soil erosion.4. Discuss how to control soil erosion.

TermsTerms

Conservation tillageConservation tillage ContourContour Contour tillageContour tillage FallowFallow Graded terracesGraded terraces Grassed waterwayGrassed waterway Gully erosionGully erosion Level terracesLevel terraces

RillRill Rill erosionRill erosion Sheet erosionSheet erosion Splash erosionSplash erosion Strip-croppingStrip-cropping TerracesTerraces T valueT value Universal Soil Loss Universal Soil Loss

Equation (USLE)Equation (USLE)

Interest ApproachInterest Approach

Successful police officers and detectives work for hours Successful police officers and detectives work for hours trying to understand how a criminal operates so they can trying to understand how a criminal operates so they can stop him. stop him.

An agricultural producer must work the same way. He or An agricultural producer must work the same way. He or she must become a soil detective. The crime to be she must become a soil detective. The crime to be solved is robbery. Soil erosion is a thief that steals the solved is robbery. Soil erosion is a thief that steals the precious soil that the producer needs to raise a profitable precious soil that the producer needs to raise a profitable crop. In order for the producer to stop soil erosion, he or crop. In order for the producer to stop soil erosion, he or she must first understand how erosion works.she must first understand how erosion works.

How does soil erosion occur?How does soil erosion occur? Erosion is a form of work, which requires Erosion is a form of work, which requires

energy. energy. The energy comes from a falling raindrop, The energy comes from a falling raindrop,

blowing wind or running water. blowing wind or running water. The energy of a falling raindrop relates to its The energy of a falling raindrop relates to its

size and especially to its speed. size and especially to its speed. A 2 inch per hour rainfall has the same A 2 inch per hour rainfall has the same

energy as a 1 pound object falling 47 feet energy as a 1 pound object falling 47 feet onto 1 square foot of soil.onto 1 square foot of soil.

The erosive energy of running water depends The erosive energy of running water depends on its volume and speed of flow.on its volume and speed of flow.

The process of soil erosion follows a The process of soil erosion follows a simple, systematic progression each and simple, systematic progression each and every time.every time.

There are three basic steps to soil erosion.There are three basic steps to soil erosion. They are detachment, transport, and They are detachment, transport, and

deposition.deposition.

DetachmentDetachment First, the impact of raindrops shatters First, the impact of raindrops shatters

surface aggregates and loosens soil surface aggregates and loosens soil particles. particles.

Some of the particles float into soil voids, Some of the particles float into soil voids, sealing the soil surface so water cannot sealing the soil surface so water cannot readily infiltrate the soil.readily infiltrate the soil.

The scouring action of running water also The scouring action of running water also detaches some soil particles.detaches some soil particles.

TransportTransport In this step the detached In this step the detached

soil grains move in flowing soil grains move in flowing water and are carried down water and are carried down slopes.slopes.

DepositionDeposition In this final stage, the soil In this final stage, the soil

is deposited when the is deposited when the water slows down.water slows down.

There are four factors that determine how There are four factors that determine how susceptible a soil is to soil erosion. susceptible a soil is to soil erosion. The factors are texture and structure, The factors are texture and structure,

slope, surface roughness, and soil slope, surface roughness, and soil cover.cover.

Texture and StructureTexture and Structure Soil structure influences infiltration of water.Soil structure influences infiltration of water. Good soil structure allows water to enter the Good soil structure allows water to enter the

soil, thus reducing the amount of water soil, thus reducing the amount of water runoff.runoff.

Soil texture has two effects on soil erosion. Soil texture has two effects on soil erosion. These are infiltration and ease of These are infiltration and ease of detachment.detachment.

InfiltrationInfiltration Like soil structure, texture also affects Like soil structure, texture also affects

the rate at which water can enter the the rate at which water can enter the soil. soil.

Less water running on the surface of the Less water running on the surface of the soil, means less soil can be transported.soil, means less soil can be transported.

Ease of detachmentEase of detachment Soil particles of different sizes vary in Soil particles of different sizes vary in

how easily they can be detached. how easily they can be detached. Silt particles are the most easily Silt particles are the most easily

detached.detached.

Slope—There are two components that Slope—There are two components that determine slope. They are length and determine slope. They are length and grade.grade. Water runoff velocity will increase as Water runoff velocity will increase as

slope grade increases. This causes an slope grade increases. This causes an increase in the erosive energy of the increase in the erosive energy of the runoff water.runoff water.

On a long slope, a greater surface area On a long slope, a greater surface area is collecting water, increasing flow is collecting water, increasing flow volume. Running water can also pick up volume. Running water can also pick up speed as it flows down a long slope.speed as it flows down a long slope.

Surface roughnessSurface roughness A rough soil surface slows the downhill A rough soil surface slows the downhill

flow of water. flow of water. Surface roughness depends a great deal Surface roughness depends a great deal

on the tillage practice used on the land. on the tillage practice used on the land. In conventional tillage, the seedbed is In conventional tillage, the seedbed is

left smooth with very few ridges. Chisel left smooth with very few ridges. Chisel plowing leaves the seedbed rough. plowing leaves the seedbed rough. Tillage across slopes, or on the contour, Tillage across slopes, or on the contour, also acts to slow water flow.also acts to slow water flow.

Traditional seed Bed!Traditional seed Bed!Chisel plowing!Chisel plowing!

Soil coverSoil cover Bare soil is fully exposed to the erosive Bare soil is fully exposed to the erosive

forces of raindrop impact and the forces of raindrop impact and the scouring of running water. scouring of running water.

Soil cover reduces the energy available Soil cover reduces the energy available to cause erosion to the soil. to cause erosion to the soil.

A mulch, cover, A mulch, cover, or crop residue or crop residue absorbs the absorbs the energy of the energy of the falling raindrop. falling raindrop.

This reduces the This reduces the amount of soil amount of soil detachment.detachment.

What are the various types of What are the various types of soil erosion?soil erosion?

There are two basic types of soil erosion. There are two basic types of soil erosion. They are water erosion and wind erosion.They are water erosion and wind erosion.

Water erosionWater erosion The process of soil erosion as The process of soil erosion as

discussed in Objective 1 of this lesson discussed in Objective 1 of this lesson can lead to various types of water can lead to various types of water erosion.erosion.

Splash erosion is the direct movement of Splash erosion is the direct movement of soil by splashing. soil by splashing. A soil grain can be thrown as far as five A soil grain can be thrown as far as five

feet by a raindrop splash. feet by a raindrop splash. These splashed particles fill the voids These splashed particles fill the voids

between other aggregates and seal the between other aggregates and seal the soil surface.soil surface.

Sheet erosion is the removal of a thin layer Sheet erosion is the removal of a thin layer of soil in a sheet. of soil in a sheet. On gentle slopes, or near the tops of On gentle slopes, or near the tops of

steeper slopes, water moves in tiny steeper slopes, water moves in tiny streams too small to be noticed. streams too small to be noticed.

Sheet erosion can go unnoticed until the Sheet erosion can go unnoticed until the subsoil appears.subsoil appears.

Rill erosion causes a series of many small Rill erosion causes a series of many small channels on a slope. channels on a slope. Water collects in the channels, picking up Water collects in the channels, picking up

energy as it runs down the slope. energy as it runs down the slope. The small channel or rill is small enough to be The small channel or rill is small enough to be

filled in by common tillage.filled in by common tillage.

Gully erosion is the most highly visible Gully erosion is the most highly visible erosion. erosion. Gullies are so large the equipment Gullies are so large the equipment

cannot cross them. cannot cross them. Gullies usually begin to form near the Gullies usually begin to form near the

bottom of a slope or on steep slopes.bottom of a slope or on steep slopes.

Wind erosionWind erosion The process is The process is

similar to that of similar to that of water erosion.water erosion.

The energy is The energy is produced by produced by wind blowing wind blowing across the soil across the soil surface instead surface instead of water running of water running down a slope.down a slope.

Wind erosion Wind erosion accounts for accounts for about 40 percent about 40 percent of the soil loss in of the soil loss in the United the United States.States.

Dry areas with Dry areas with high winds are high winds are more likely to more likely to lose soil due to lose soil due to wind erosion.wind erosion.

How do I estimate the How do I estimate the amount of soil loss from amount of soil loss from

water erosion?water erosion? Using various soil loss factors, the Using various soil loss factors, the

Universal Soil Loss Equation (USLE) has Universal Soil Loss Equation (USLE) has been developed to predict the average soil been developed to predict the average soil loss from sheet and rill erosion on a loss from sheet and rill erosion on a specific site.specific site.

It was developed over several years by the It was developed over several years by the Natural Resources Conservation Service. Natural Resources Conservation Service.

Producers can use the equation to Producers can use the equation to estimate the rate of soil loss on their land estimate the rate of soil loss on their land and compare that rate with soil’s T value. and compare that rate with soil’s T value.

T value is soil loss tolerance value. That is T value is soil loss tolerance value. That is the amount of soil loss that can be the amount of soil loss that can be tolerated by that soil type. tolerated by that soil type.

Each soil type has its own T value. Each soil type has its own T value.

The formula for The formula for USLE is A = R × K USLE is A = R × K × LS × C × P. × LS × C × P.

Each letter in the Each letter in the formula represents formula represents a specific soil loss a specific soil loss factor.factor.

Average Annual Soil Loss (A)—“A” represents Average Annual Soil Loss (A)—“A” represents the average annual soil erosion loss in tons the average annual soil erosion loss in tons per acre. This factor should be less than the T per acre. This factor should be less than the T value for the soil type.value for the soil type.

Rainfall (R)—“R” represents the erosion Rainfall (R)—“R” represents the erosion potential inherent in the rainfall patterns of a potential inherent in the rainfall patterns of a particular area. The factors were developed particular area. The factors were developed from the U.S. Weather Service data taken from the U.S. Weather Service data taken over a 22 year period.over a 22 year period.

Soil Erodibility (K)—This factor reflects the Soil Erodibility (K)—This factor reflects the fact that various soils erode at different fact that various soils erode at different rates because of different physical rates because of different physical characteristics, such as texture, structure, characteristics, such as texture, structure, organic matter content, and soil depth. organic matter content, and soil depth. Each different soil type has a specific K Each different soil type has a specific K value.value.

Slope Length and Steepness (LS)—This Slope Length and Steepness (LS)—This factor represents the erosion potential for factor represents the erosion potential for a particular combination of slope length a particular combination of slope length and slope steepness. Slope length is not and slope steepness. Slope length is not the distance from the highest point in the the distance from the highest point in the field to the lowest. It must be determined field to the lowest. It must be determined where the water will flow. Concentrate on where the water will flow. Concentrate on natural water flow areas.natural water flow areas.

Cropping Factor (C)—This reflects the Cropping Factor (C)—This reflects the reduction in soil erosion when a specific reduction in soil erosion when a specific cropping system is compared with cropping system is compared with continuous fallow or where the soil is tilled, continuous fallow or where the soil is tilled, but no crop is grown. The C factor of 1.0 is but no crop is grown. The C factor of 1.0 is assigned to continuous fallow. C factors are assigned to continuous fallow. C factors are determined by the climatic conditions of a determined by the climatic conditions of a region, crop rotation used, tillage methods region, crop rotation used, tillage methods used, and crop residue on the field.used, and crop residue on the field.

Conservation Conservation practice (P)—This practice (P)—This represents the represents the reduction of soil reduction of soil erosion due to the erosion due to the implementation of implementation of various various conservation conservation practices such as practices such as contour farming, contour farming, strip cropping, and strip cropping, and terracing.terracing.

How can soil erosion be How can soil erosion be controlled?controlled?

Preventing or stopping soil erosion is a Preventing or stopping soil erosion is a major goal of every producer. major goal of every producer.

Once a producer understands the causes Once a producer understands the causes of soil erosion and has estimated the of soil erosion and has estimated the amount of soil loss on his farm, a plan of amount of soil loss on his farm, a plan of action must be developed. action must be developed.

All methods of controlling water erosion are All methods of controlling water erosion are based on one of the following three actions:based on one of the following three actions: Reducing raindrop impact to lessen Reducing raindrop impact to lessen

detachment.detachment. Reducing or slowing water runoff. This Reducing or slowing water runoff. This

lessens detachment by scouring and lessens detachment by scouring and reduces the amount of soil that can be reduces the amount of soil that can be transported.transported.

Carrying excess water off the field safely.Carrying excess water off the field safely.

There are several management practices There are several management practices and tools that a land owner can use to and tools that a land owner can use to reduce and prevent soil erosion on reduce and prevent soil erosion on property.property. Conservation tillage—Tillage practices Conservation tillage—Tillage practices

that leave crop residues on a rough soil that leave crop residues on a rough soil surface to reduce erosion. These surface to reduce erosion. These practices dramatically reduce sheet and practices dramatically reduce sheet and rill erosion. It is also the lowest cost rill erosion. It is also the lowest cost conservation method per ton of soil conservation method per ton of soil saved.saved.

Soil cover—Whenever soil is worked or Soil cover—Whenever soil is worked or exposed, covering the surface with mulch exposed, covering the surface with mulch or vegetation reduces erosion.or vegetation reduces erosion.

Crop rotation—This practice reduces Crop rotation—This practice reduces erosion if a close-growing crop like small erosion if a close-growing crop like small grains or forages are included. These grains or forages are included. These close-growing crops reduce the close-growing crops reduce the detachment and transport energy of detachment and transport energy of water. They also improve the physical water. They also improve the physical properties of the soil so that water seeps properties of the soil so that water seeps into the soil better.into the soil better.

Grassed waterways—A shallow, Grassed waterways—A shallow, sodded, wide ditch that runs down a sodded, wide ditch that runs down a slope. It is designed to carry excess slope. It is designed to carry excess water off the field safely.water off the field safely.

Contour tillage—Tillage following the Contour tillage—Tillage following the contours of a slope, rather than up and contours of a slope, rather than up and down a slope. This practice works best down a slope. This practice works best on permeable soils in areas of low on permeable soils in areas of low intensity rainfall.intensity rainfall.

Contour tillage!Contour tillage! Grassed Waterway!Grassed Waterway!

Strip-cropping—The planting of different Strip-cropping—The planting of different types of crops in alternating strips to types of crops in alternating strips to prevent wind or water erosion. Strips are prevent wind or water erosion. Strips are usually planted on a slope contour or usually planted on a slope contour or across the direction of the prevailing wind.across the direction of the prevailing wind.

Improving organic matter—This can Improving organic matter—This can greatly reduce erosion because moisture greatly reduce erosion because moisture will enter the soil more quickly.will enter the soil more quickly.

Terraces—A series of low ridges Terraces—A series of low ridges and shallow channels running and shallow channels running across a slope or on the contour to across a slope or on the contour to capture water so it can soak into the capture water so it can soak into the soil. soil.

Level terraces parallel the slope Level terraces parallel the slope and do not empty into a and do not empty into a waterway. This is used where soil waterway. This is used where soil is permeable enough that water is permeable enough that water can seep in once it is captured in can seep in once it is captured in a terrace. a terrace.

Graded terraces are needed Graded terraces are needed where water cannot soak in where water cannot soak in enough. These terraces slope enough. These terraces slope gently towards a waterway or an gently towards a waterway or an underground tile outlet.underground tile outlet.

Review/SummaryReview/Summary

How does soil erosion occur?How does soil erosion occur? What are the various types of soil erosion?What are the various types of soil erosion? How do I estimate the amount of soil loss How do I estimate the amount of soil loss

from water erosion?from water erosion? Hoe can soil erosion be controlled?Hoe can soil erosion be controlled?

The End!The End! Erosion!Erosion!