August 2008 Water-Caused Soil Erosion This presentation is from Virginia Tech and has not been edited by the Georgia Curriculum Office

August 2008 Objectives Explain how land capability classes relate to wise soil use Describe main vegetative methods used to control water caused soil erosion Describe main mechanical methods used to control erosion Design proper control strategies

August 2008 Land Capability Classes Range from Class I to Class VIII Classes I–IV are suitable for row crop production –Class I is the best. Nearly flat with little erosion –Class IV has moderate slopes and is prone to high levels of erosion –Should be covered with vegetation continuously

August 2008 Class I

August 2008 Class III

August 2008 Classes V & VI Class V is very nearly level but it may be too wet or rocky for crop production Class VI is very rocky and steep with very shallow topsoil Good for permanent grazing and forests Overgrazing should be avoided

August 2008 Class VI

August 2008 Classes VII & VIII Almost impassible Limited grazing and forest production Class VIII is not suitable for any farming

August 2008 Class VIII

August 2008 Class exercise classify the land in the following pictures 1

August

4 5

Control Measures Vegetative Mechanical

August 2008 Vegetative Control Cover crops Crop rotation Strip cropping Grassed waterways

August 2008 Cover Crops Close growing crop grown on the field when the cash crop isn’t growing Winter wheat, rye, vetch, etc Reduce erosion, improve soils organic matter, and improve soil tilth (workability)

August 2008 Crop Rotation Orderly and repeated sequence of different crops grown on the same field Example: 3–year rotation using corn, soybeans, wheat Advantages –Soil tilth is better –Improves water absorption –Reduces erosion –Increases organic matter –Improves moisture storing capacity

August 2008 Strip Cropping Alternating bands of different crops Laid out on the contour or across a prevailing slope Hay strip, corn strip, hay strip Hay strips increase water absorption, holds the soil in place, reduces gullying, & slows down running water

August 2008 Grassed Waterways Natural drainageway permanently covered by vegetation Used widely to prevent gullying in natural draws Types –Trapezoidal –V–bottomed –Saucer–most common Perrenial grasses such as fescue or bluegrass are typically used Quickly establish sod (overseed, fertilize, mulch)

August 2008 Mechanical Control Conservation Tillage Contour Farming Terraces Fencing

August 2008 Conservation Tillage Tillage system that is economically practical for crop production and aids in soil and water conservation Crop residue from previous crop helps protect soil Common methods include minimum till, no till stubble plant and strip tilling Advantages –Less energy and time are require –Soil moisture levels increase w/ increase in soil organic-matter levels –Reduces soil erosion

August 2008 Disadvantages –Increase in weed, insect, and disease problems –Crop residue ties up nitrogen thus requiring more fertilization

August 2008 Contour Farming Plowing around the hill instead of up and down it Prevents runoff from moving straight down the hill

August 2008 Terraces Larger surface channels constructed on a contour with a controlled rate of fall Terraces are needed if slope exceeds about 2% Should be designed by Soil Conservation Service Example: waterbreaks in old logging road

August 2008 Fencing Fencing cattle away from creeks and ponds Greatly reduce creek bank erosion Reduces cattle waste from directly entering the water source

August 2008 Developing Control Strategies

August 2008 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.