Water-Caused Soil Erosion

This presentation is from Virginia This presentation is from Virginia Tech and has not been edited by the Tech and has not been edited by the

Georgia Curriculum OfficeGeorgia Curriculum Office

Objectives

Explain how land capability classes relate to Explain how land capability classes relate to wise soil usewise soil use

Describe main vegetative methods used to Describe main vegetative methods used to control water caused soil erosioncontrol water caused soil erosion

Describe main mechanical methods used to Describe main mechanical methods used to control erosioncontrol erosion

Design proper control strategiesDesign proper control strategies

Land Capability Classes

Range from Class I to Class VIIIRange from Class I to Class VIII Classes I–IV are suitable for row crop productionClasses I–IV are suitable for row crop production

Class I is the best. Nearly flat with little Class I is the best. Nearly flat with little erosionerosion

Class IV has moderate slopes and is prone to Class IV has moderate slopes and is prone to high levels of erosionhigh levels of erosion

Should be covered with vegetation Should be covered with vegetation continuouslycontinuously

Class I

Class III

Classes V & VI

Class V is very nearly level but it may be Class V is very nearly level but it may be too wet or rocky for crop productiontoo wet or rocky for crop production

Class VI is very rocky and steep with very Class VI is very rocky and steep with very shallow topsoilshallow topsoil

Good for permanent grazing and forestsGood for permanent grazing and forests Overgrazing should be avoidedOvergrazing should be avoided

Class VI

Classes VII & VIII

Almost impassibleAlmost impassible Limited grazing and forest productionLimited grazing and forest production Class VIII is not suitable for any farmingClass VIII is not suitable for any farming

Class VIII

Class exercise

classify the land in the following picturesclassify the land in the following pictures

1

2

3

4

5

Control Measures

Vegetative Vegetative

MechanicalMechanical

Vegetative Control

Cover cropsCover crops Crop rotationCrop rotation Strip croppingStrip cropping Grassed waterwaysGrassed waterways

Cover Crops

Close growing crop grown on the field Close growing crop grown on the field when the cash crop isn’t growing when the cash crop isn’t growing

Winter wheat, rye, vetch, etc Winter wheat, rye, vetch, etc Reduce erosion, improve soils organic Reduce erosion, improve soils organic

matter, and improve soil tilth (workability) matter, and improve soil tilth (workability)

Crop Rotation Orderly and repeated sequence of different crops Orderly and repeated sequence of different crops

grown on the same fieldgrown on the same field Example: 3–year rotation using corn, soybeans, wheat Example: 3–year rotation using corn, soybeans, wheat AdvantagesAdvantages

Soil tilth is better Soil tilth is better Improves water absorption Improves water absorption Reduces erosion Reduces erosion Increases organic matter Increases organic matter Improves moisture storing capacityImproves moisture storing capacity

Strip Cropping

Alternating bands of different crops Alternating bands of different crops Laid out on the contour or across a Laid out on the contour or across a

prevailing slope prevailing slope Hay strip, corn strip, hay strip Hay strip, corn strip, hay strip Hay strips increase water absorption, holds Hay strips increase water absorption, holds

the soil in place, reduces gullying, & slows the soil in place, reduces gullying, & slows down running water down running water

Grassed Waterways

Natural drainageway permanently covered by Natural drainageway permanently covered by vegetationvegetation

Used widely to prevent gullying in natural drawsUsed widely to prevent gullying in natural draws Types Types

Trapezoidal Trapezoidal V–bottomed V–bottomed Saucer–most common Saucer–most common

Perrenial grasses such as fescue or bluegrass are Perrenial grasses such as fescue or bluegrass are typically usedtypically used

Quickly establish sod (overseed, fertilize, mulch)Quickly establish sod (overseed, fertilize, mulch)

Mechanical Control

Conservation TillageConservation Tillage Contour FarmingContour Farming TerracesTerraces FencingFencing

Conservation Tillage Tillage system that is economically practical for Tillage system that is economically practical for

crop production and aids in soil and water crop production and aids in soil and water conservationconservation

Crop residue from previous crop helps protect soilCrop residue from previous crop helps protect soil Common methods include minimum till, no till Common methods include minimum till, no till

stubble plant and strip tillingstubble plant and strip tilling AdvantagesAdvantages

Less energy and time are requireLess energy and time are require Soil moisture levels increase w/ increase in soil Soil moisture levels increase w/ increase in soil

organic-matter levelsorganic-matter levels Reduces soil erosionReduces soil erosion

DisadvantagesDisadvantages Increase in weed, insect, and disease Increase in weed, insect, and disease

problemsproblems Crop residue ties up nitrogen thus Crop residue ties up nitrogen thus

requiring more fertilizationrequiring more fertilization

Contour Farming

Plowing around the hill instead of Plowing around the hill instead of up and down it up and down it

Prevents runoff from moving Prevents runoff from moving straight down the hill straight down the hill

Terraces

Larger surface channels constructed on Larger surface channels constructed on a contour with a controlled rate of fall a contour with a controlled rate of fall

Terraces are needed if slope exceeds Terraces are needed if slope exceeds about 2% about 2%

Should be designed by Soil Should be designed by Soil Conservation Service Conservation Service

Example: waterbreaks in old logging Example: waterbreaks in old logging roadroad

Fencing

Fencing cattle away from creeks Fencing cattle away from creeks and pondsand ponds

Greatly reduce creek bank erosionGreatly reduce creek bank erosion Reduces cattle waste from directly Reduces cattle waste from directly

entering the water sourceentering the water source

Developing Control Strategies

A logging crew is moving to this area. The crew plans to clearcut the forest. What suggestions can you provide the crew to minimize soil erosion.