Submitted to: Forage Focus
Publication Type: Trade Journal
Publication Acceptance Date: 2/15/2007
Publication Date: 3/1/2007
Citation: Russelle, M.P. 2007. Drought and alfalfa nutrition. Forage Focus. p. 7. Interpretive Summary:
Technical Abstract: Although established alfalfa can access deep subsoil water, dry topsoils limit the availability of many nutrients. Dry topsoils can limit the uptake of many plant nutrients. With the potential for drought in 2007, farmers should consider fertilizing alfalfa if the soil tends to be droughty, is shallow, or has low fertility. Under these conditions, topdressing alfalfa after the first harvest with commercial fertilizer or manure can improve yields and forage quality. Application rate should be based on soil tests taken early this spring. State regulations should be followed for manure application. With either source, apply as soon as possible after harvest, but only on firm soil to reduce damage from wheel traffic. Neither source will provide significant nutrients to the alfalfa if the topsoil remains dry, so the decision to fertilize should be made with an eye to the weather forecast. The water content of manure slurry can improve regrowth, but broadcast slurry can coat the leaves with solids that prevent photosynthesis and suffocate the tissue. When broadcasting slurry on alfalfa, apply no more than 1.5 tons of solids per acre. Manure from a herd with diseases like Johne's should not be used on alfalfa that will be stored as hay because the organisms persist on the soil and plant surfaces and could infect healthy livestock.