Alfalfa adds nitrate to the soil

Letter from Charles Brink to:

July 23, 1997

Dear Wendy

This is a reprint of a portion of a paper on the Internet. I have provided you with the URL for the document with the references that are cited.

The proposal from Lillian Smith and Kenneth D. Schmidt, Geologist No. 1578 Hydrogeologist No. 176 states in part:

Areas of known historical and current feedlot or high-density animal holding areas will be investigated. For abandoned feedlot situations, manure scraping and removal followed by planting alfalfa and clover, surface cover, or other high nitrogen consuming crops, can reduce the potential for nitrate leaching to groundwater. Such options will be reviewed regarding their economical and technical feasibility. The runoff potential for such areas will also be evaluated.

As you can see from this citation and its references Alfalfa adds nitrate to the soil, it does not consume nitrates. Alfalfa obtains nitrogen directly from the air and fixes it into nodules and leaves these nodules in the soil. A crop of alfalfa will substantially increase nitrate available to pollute groundwater.

Since their expert doesn't even know this basic fact, then how can we rely on anything he says?

If you accept the position that alfalfa adds nitrate, let me know or I will acquire more citations from public documents supporting our position that alfalfa increases nirate loading and does not lower it.

You may ask Kenneth D. Schmidt for his documentation supporting his position that alfalfa produces a net reduction in nitrates.

Charles Brink

CC Denise Dee Lillian Smith Water Committee

This is an excerpt from Environmental Working Group

The Environmental Working Group is a nonprofit environmental research organization based in Washington, D.C. The Environmental Working Group is a project of the Tides Foundation, a California Public Benefit Corporation based in San Francisco that provides administrative and program support services to nonprofit programs and projects.

Kenneth A. Cook, President
Mark B. Childress, Vice President for Policy
Richard Wiles, Vice President for Research

http://www.ewg.org/pub/home/Reports/Nitrate/NitrateContents.html

Pouring It On: Nitrate Contamination of Drinking Water

This is an excerpt from http://www.ewg.org/pub/home/Reports/Nitrate/NitrateAlts.html

Another substantial source of nitrogen is that made available from nitrogen-fixing crops such as alfalfa or beans. When these crops are grown, they leave available nitrogen in the soil, and when the next crop is planted, farmers do not need to apply as much fertilizer. As with manure, however, most producers do not fully account for this crop-supplied nitrogen. A 1990 study concluded that 56 percent of fields where corn was grown following alfalfa had more than twice as much nitrogen as necessary for economically optimal yields; 86 percent had more than the optimal amount of nitrogen (El Hout and Blackmer 1990). [1].

These and numerous other analyses show that there is ample room for growers to improve nutrient management by accurately accounting for all nitrogen inputs. In the Corn Belt, alfalfa is grown on approximately 8 percent of cropland and contributes approximately 1.1 million tons of nitrogen annually (NRC 1993) [2]. If farm practices accounted for the nitrogen available from alfalfa and manure, fertilizer-N applications in the Corn Belt could be reduced by eight to fourteen percent (Peterson and Russelle 1991).[3]

This would reduce nitrogen fertilizer applications by nearly one billion pounds per year, reduce the risk to water supplies, and save the region's farmers approximately $150 million annually in production costs. In some states with greater alfalfa production, fertilizer could be reduced even more than the regional average. For example, by simply accounting for nitrogen from alfalfa, fertilizer applications could be reduced by 20-36 percent in Michigan, and by up to a whopping 66 percent in Wisconsin (Peterson and Russelle 1991).[3] And these conservative estimates do not include inputs from soybeans and all sources of manure.

References

[1] El-Hout, N.M. and A.M. Blackmer. 1990. Nitrogen status of corn after alfalfa in 29 Iowa fields. Journal of Soil and Water Conservation. January-February. 115-117

[2] National Research Council. 1993. Board on Agriculture. Soil and Water Quality: An Agenda For Agriculture. National Academy Press. Washington, DC. NRDC. 1994. Natural Resources Defense Council.

[3] Peterson, T.A. and M.P. Russelle. 1991. Alfalfa and the nitrogen cycle in the corn belt. Journal of Soil and Water Conservation. May-June. 229-235.

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