Wednesday, 9 November 2005
8

Sequestering Manure P and Improving Productivity of Marginal Land with Vegetative Barriers.

Seth M. Dabney, USDA-ARS National Sedimentation Lab, 598 McElroy Drive, P.O. Box 1157, Oxford, MS 38655-2900, Ardeshir Adeli, USDA-ARS Waste Management & Forage Research, 810 Hwy 12 East, P.O. Box 5367, Mississippi State, MS 39762, Phillip R. Owens, Purdue Univ., Lilly Hall of Life Sciences, 915 W. State Street, West Lafayette, IN 47907, Joel L. Douglas, USDA-NRCS Central National Technology Support Center, 501 W. Felix St., FWFC, Bldg. 23, PO Box 6567, Fort Worth, TX 76115, and Scott Edwards, USDA-NRCS Plant Materials Program, 3737 Government Street, Alexandria, LA 71302.

Farming between vegetative barriers results in the gradual development of bench terraces. Soil upslope of barriers gradually builds up while soil is removed by tillage and water erosion down slope of each barrier. For this to be desirable, soil profiles must have sufficient depth to retain productivity where benches will develop, giving consideration to subsoil characteristics and response to amendments. Bench terrace development between vegetative barriers has been monitored since 1993 on an eroded Loring silt loam soil with an initial slope of about 7%. This soil has a fragipan in the subsoil that is infertile and restrictive of root growth and water percolation and so is a marginal candidate for benching with vegetative barriers. Between 1993 and 2005, benches up to 1 m high have developed across vegetative barriers spaced about 20 m apart. Slopes in the cropped intervals have decreased from 7% to about 4%, and as little as 2% in thalweg areas. Benching has created spatial variability in soil organic carbon, extractable phosphorus, soil water, and crop productivity. A study was initiated in 2005 to determine how tillage and/or manure application affects the productivity and soil properties of degraded and aggraded areas. We hypothesize that the combination of deep tillage to loosen the subsoil, manure application to provide nutrients and organic matter, and surface tillage to incorporate manure and facilitate benching has the greatest potential of improving productivity while simultaneously avoiding a surface buildup of soil test phosphorus. We hope that vegetative barriers can provide adequate soil erosion control, sequester carbon and phosphorous in the developing bench terraces, and transform marginal land into productive cropland.

Handout (.pdf format, 298.0 kb)

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