Northeast Region Certified Crop Adviser (NRCCA) Study Resources

In This Section

• PO 39 Erosion
• PO 40 Consequences of erosion & sedimentation
• PO 41.1-2 Inter-rill & rill erosion
• PO 41.3-4 Gully & streambank erosion
• PO 42 Erodibility
• PO 43 Climatic effects on erosion
• PO 44 Slope effects on erosion
• PO 45 RUSLE
• PO 46 Erosion reduction with agronomy
• PO 47.1-2 Structural conservation 1
• PO 47.3-4 Structural conservation 2
• PO 47.5-6 Structural conservation 3
• PO 48 Tillage
• PO 49.0 Tillage systems
• PO 49.1-2 Plow-till / no-till
• PO 49.3-5 Mulch-till / ridge-till / zone tillage
• PO 51.1-2 Adaptability of tillage systems 1
• PO 51.3-4 Adaptability of tillage systems 2
• PO 52 Tillage practices
• PO 53 Tillage systems
• PO 54 Soil Tilth
• PO 55. Tillage conditions
• Summary

Competency Area 5: Soil conservation AEM

PO 47. Understand the basic approaches to structural soil conservation practices.

1. Filter strips
2. Grassed waterways
3. Diversions<
4. Ponds
5. Terraces
6. Drop structures

Terraces

Terraces are broad cross-slope channels similar to diversions, used to control erosion on cropland and built so that crops can be grown on the terrace. Storage terraces store water until it can be absorbed by the soil or released to stable outlet channels or through underground outlets. Storage terraces are usually designed to drain completely in 48 hours to avoid waterlogging within the terrace. Gradient terraces are gently sloping channels constructed almost perpendicular to the natural field waterway. Various different types (constructed shapes) of terraces include bench, broad-base, channel-slope to reduce field slope lengths, and collect runoff water and carry it to a stable outlet like a type, conservation bench, graded, level, Mangum, narrow-base, parallel, nonparallel, ridge-type, ridgeless-channel, and steep-backslope terrace.

Terraces as part of soil conservation

Photo courtesy of NRCS

http://photogallery.nrcs.usda.gov

Drop structures

Drop structures are hydraulic structures for safely transferring water in a channel to a lower level channel without causing erosion. They can be vertical or slanting and are typically built with a vertical riser conduit (drop-inlet spillway) or an apron (drop spillway) with a plunge pool at the base. The plunge pool acts to dissipate flow and reduce erosion of the stream bottom.

Drop structure

image source:

http://www.ars.usda.gov/SP2UserFiles/Place/53680000/presentations/trashscreen/squarescreen1.jpg