Author
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Russelle, Michael |
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Submitted to: Grain Legumes
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 1/17/2013 Publication Date: 7/31/2014 Citation: Russelle, M.P. 2014. Environmental benefits of growing perennial legumes in cropping systems. Grain Legumes. 4:11-12. Interpretive Summary: Alfalfa is a long-lived crop used mainly to feed livestock, but it provides additional environmental benefits to the farmer and society. This review article describes many of those benefits and indicates areas that need further research. Alfalfa helps protect water quality by reducing nitrate losses to ground water and surface water, so it can be used to clean up excess nitrate in abandoned farmyards or at other contaiminated sites. Alfalfa also adds organic nitrogen to the soil, reducing the need for commercial fertilizer. This helps farmers save money, and makes their farming systems more sustainable. However, there are many cases where the crop that follows alfalfa needs additional fertilizer, yet there are no methods to identify those cases. Livestock manure can be beneficial to alfalfa, but the risks and benefits have not been adequately researched. Because most US farmers do not achieve the yields that are possible with alfalfa, it is important to discover and remove yield-limiting factors to achieve higher economic and environmental benefits. New alfalfa cultivars can be developed to enhance environmental benefits. Technical Abstract: Alfalfa offers several environmental benefits to farmers and society. Reduced nitrate leaching due to slower water flow and excellent nitrate removal are valuable in farm fields and at remediation sites. Improved N supply to following crops reduces energy use, economic costs, and greenhouse gas emissions, but reliable indicators are needed to identify which fields need supplemental N after alfalfa. Livestock manure is applied to alfalfa by farmers, but too little is known about the benefits and risks. Critical needs are on-farm estimates of yield and N2 fixation and for broadened plant improvement objectives to explicitly include environmentally beneficial traits. |
