Willow posts are a low-cost, environmentally friendly tool for controlling stream bank erosion and restoring degraded riparian plant communities. Willow trees may be propagated by planting cuttings in moist soil. The cuttings develop roots and shoots and grow rapidly. Large 3-inch-diameter cuttings—called posts—are useful in controlling rapid erosion of stream channels. However, low survival rates have been reported in certain areas of the country. ARS and cooperating university scientists suspected that soil conditions might be the primary factor. To find out, they designed and conducted field studies of the relationships between soil conditions and survival and growth of willow posts planted along two rapidly eroding streams in Mississippi. Plant vigor and growth were significantly lower for posts growing in soils that were too wet or too dry. Optimal conditions for growing posts were moderate elevations, about a half yard above the stream level at low flow. At this elevation, soils tended to have adequate moisture but frequent drainage. The scientists also found a close relationship between soil texture and survival of willow posts. Posts growing in silty-clay soils had a low survival rate, decreased height, smaller leaf size, and lower leaf tissue chlorophyll content than those growing in sandy soils. Since locations with well-drained, sandy soils and adequate moisture had high post growth and survival rates, targeting these zones will best ensure successful streambank restoration efforts using willow posts. Research continues on developing predictive tests for evaluating specific sites for planting willow posts.

National Sedimentation Laboratory, Oxford, MS
Douglas Shields, (601) 232-2919, shields@sedlab.olemiss.edu

ARS and Auburn University scientists are teaming up on a joint project to help cotton growers correct soil problems in the Tennessee Valley, which includes Tennessee and parts of Alabama, Mississippi, Kentucky, Georgia, North Carolina and Virginia. Although the land in this area is fertile, the soils are heavily eroded and heavily compacted, and plant roots don't extend deep into the soil. Years of conventional tillage, coupled with little crop rotation, have severely depleted the soil organic matter, in some areas to less than 1 percent. In field studies, ARS scientists found deep-tilling to 17 inches and planting a rye cover crop in fall increases yields and reduces soil compaction. Three-year average yields for this system were about 1,040 pounds of lint per acre. The best conservation tillage treatment gave yields that were 14 percent higher than with conventional tillage and 18 percent higher than with no tillage without using a cover crop, the system Tennessee Valley farmers adopted when they first went to conservation tillage. At current prices for cotton, fall deep tillage in combination with a rye cover crop paid for itself more than three times over.

National Soil Dynamics Laboratory, Auburn, AL
D. Wayne Reeves/Randy L. Raper, (334) 844-4666/(334) 844-4654,
wreeves@acesag.auburn.edu/rlraper@eng.auburn.edu