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Title: Use of Alfalfa for Soil Phosphorus Removal Following Long-Term Manure Application

Author
item Eigenberg, Roger
item Woodbury, Bryan
item FERGUSON, RICHARD - University Of Nebraska
item Nienaber, John
item Spiehs, Mindy

Submitted to: Proceedings of the American Society of Agricultural and Biological Engineers International (ASABE)
Publication Type: Proceedings
Publication Acceptance Date: 5/19/2009
Publication Date: 6/24/2009
Citation: Eigenberg, R.A., Woodbury, B.L., Ferguson, R., Nienaber, J.A., Spiehs, M.J. 2009. Use of Alfalfa for Soil Phosphorus Removal Following Long-Term Manure Application. In: Proceedings of the American Society of Agricultural & Biological Engineers. June 21-24, 2009. Reno, NV. ASABE Paper No. 96305. St. Joseph, Mich.:ASABE.

Interpretive Summary: Phosphorus is an essential soil nutrient for plant growth. Animal manure is an excellent plant fertilizer, but over-application can cause phosphorus to build up in soils. An alfalfa crop was tested as a way to remove excessive phosphorus from soils. Alfalfa was planted in a research field (2005) that had a history of various rates of manure addition. As a result, the field had areas with adequate phosphorus levels and areas that were excessive. Plant samples were collected from these areas prior to every alfalfa cutting. Also, soil samples from these areas were taken annually, beginning in 2006. The alfalfa plants had higher amounts of phosphorus from the areas with excessive amounts of soil phosphorus than the plants from areas that were adequate. The alfalfa harvested from the areas with excess phosphorus removed 90 kg/ha while the alfalfa from the adequate areas removed only 52 kg/ha for the same two year period.

Technical Abstract: This study was conducted to examine alfalfa remediation effects on a cornfield treated during a 10-yr period with manure at rates matching either the N (MN) or P (MP) requirements of silage corn (Zea mays L.). A commercial fertilizer (NCK) was used as a control. The site was removed from corn production with cessation of treatments and planted to alfalfa in 2005. Alfalfa plants were harvested from a 1 m2 square area at eight replicates of MN, MP and NCK prior to each cutting of alfalfa. The harvested plants were analyzed for total P. Soil samples were taken at the end of each growing season to depths of 0-15 cm and 15-30 cm. Analysis showed the MN plant samples from the MN treatments (total of 8 cuttings) had significantly (P < 0.05) higher P content compared to the NCK treatment with exception the last cutting of 2007. The alfalfa removed 90 kg/ha of P from the MN treatment over the two years compared to a 71 kg/ha for the MP treatment and 52 Kg/ha for the NCK treatment.