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ARS Home » Midwest Area » Columbia, Missouri » Cropping Systems and Water Quality Research » Research » Publications at this Location » Publication #118873


item Alberts, Edward
item Kramer, Larry

Submitted to: Soil Erosion for 21st Century Symposium
Publication Type: Proceedings
Publication Acceptance Date: 1/5/2001
Publication Date: N/A
Citation: N/A

Interpretive Summary: Since 1985, many highly erodible lands have been terraced, plus farmers have increased adoption of conservation tillage and no-tillage practices that keep crop residues on the soil surface to reduce raindrop and runoff detachment of soil. In countries such as China, India, and Indonesia, earthen terraces are formed by the natural process of erosion rather than by the mechanical method where soil is excavated and moved. While quantitative information on the mass of sediment deposition is relatively limited in these countries, observations indicate that sediment buildup behind grasses is quite high, often a meter or so every decade. In the early 1990s, ARS scientists began to seriously investigate the effectiveness of grass hedges in erosion control for U.S. conditions. In 1992, rows of stiff-stemmed grass hedges were planted within a 5.6-ha watershed located in western IA. The watershed was instrumented with a weir, water-stage recorder, and automated sediment sampler in 1975. Continuous runoff and soil loss data were collected from 1975 through 1999. For the 1975-1991 period, a relationship between annual soil loss and annual surface runoff loss was developed. The relationship was used to estimate soil losses that would have occurred during the ensuing 8 years (1992-1999)if hedges had not been planted. The total estimated soil loss was 209 Mg/ha while the total measured soil loss was 75 Mg/ha, a reduction of 64%. The results, which show that stiff stemmed grass hedges are an inexpensive alternative to terracing to reduce soil losses, will be useful to scientists, extension/education personnel, and to farmers willing to adopt natural methods of erosion control.

Technical Abstract: Stiff-stemmed grass hedges planted in narrow rows within a field offer an opportunity for effective erosion control at a reasonable cost. The objectives of this research were to evaluate the erosion control effectiveness of grass hedges in a typical field setting and to determine the amount of soil redistributed within a grass-hedged field. The research hwas conducted on a 5.6-ha watershed located in the deep loess hills region of western Iowa. The watershed was cropped primarily to continuous corn using conventional tillage practices. Collection of runoff and sediment yield data was initiated in 1975. In 1992, narrow rows of grass hedges were planted at 15.4-m intervals to accommodate 16 rows of corn. A linear regression was developed between annual sediment yield and and annual surface runoff for the 1975 through 1991 period and used to estimate annual sediment yields for the 1992 through 1999 period. Total estimated sediment tyield for the 1992-1999 period was 209 Mg/ha compared to 75 Mg/ha that was actually measured, a reduction of 64%. Analyses of soil elevation data collected with a GPS RTK system revealed that 455 Mg/ha of soil was redistributed to cause soil elevation increases near the hedges and soil elevation decreases further upslope. In areas of the watershed where rill and interrill erosion occurred, most of the soil redistributed was caused by tillage equipment moving soil downslope. The watershed has a well defined ephemeral gully network. There was considerable sediment deposition in areas where the hedges crossed the ephemeral gullies. Our results show the usefulness of narrow rows of still-stemmed grass hedges in reducing erosion and redistributing soil between hedges in a natural benching process.