Considering the different scenarios, substantial reduction in soil loss can be achieved when contouring and combined contouring and strip-cropping practices are applied to the croplands, as expected.
Up-down Cross-slope Contour farming hill slope farming ([dagger]) 20% up-down hill slope (%) Furrow grade P values Furrow grade P values 0-4 4 1.000 0.6 0.548 5-9 5 0.852 1.5 0.544 10-14 6 0.828 2.5 0.601 15-19 7 0.897 3.5 0.843 20-24 8 0.935 4.4 0.910 25-29 9 0.961 5.5 0.946 30-39 10 0.984 7.2 0.987 > 40 12 1.000 9.0 1.000 Up-down Contouring and hill slope strip-cropping (%) Furrow grade P values 0-4 0.3 0.440 5-9 0.7 0.440 10-14 1.2 0.440 15-19 1.7 0.550 20-24 2.2 0.730 25-29 2.7 0.830 30-39 3.6 0.920 > 40 4.5 0.970 ([dagger]) For cross-slope farming, the furrow grade values were recommended by the USDA-NCRS personnel (T.
Strip-Cropping. Strip-cropping (figure 18-20) can be used in all conditions along with contour tillage.
As in contour tillage, guidelines are needed to plow for strip-cropping. Strips of equal width are placed across the slope and are planted to alternating row crops, small grains, and meadow.
Where strip-cropping cannot halt erosion, terraces may be built (figure 18-23).
For the P factor, use the contour tillage or strip-cropping value.
Contour tillage, contour strip-cropping, and terraces are effective ways to slow runoff.
This system can be called contour tree buffer strips, strip-cropping with trees, or bioterracing, because a combination of trees and grass replaces terraces, grass strips, or other means of soil erosion control on hillsides of highly erodible land.
Five different systems were compared: contour tree buffer strips, terracing, conventional tillage, contour strip-cropping, and the Conservation Reserve Program (CRP).
The conservation practice of contour strip-cropping consists of strips of small grains or meadow alternated with strips of rowcrop.
In this study, four contour strip-cropping regimes were analyzed: corn/hay/soybean, corn/pasture/soybean, corn-pasture with legume/soybean, and corn/oats/soybean.
These increased yields in rowcrops not only increase annual cash flows but also give alternatives with a rowcrop component a higher economic return (Table 3), so that terraces become economically feasible at medium and high land values, contour tree buffer strips improve economically as land value rises, and contour strip-cropping becomes the economically best practice at the high land value.