Environmental Guide to Alfalfa Growth, Water Use, and Yield in Minnesota

Abstract

Alfalfa (Medicago sativa L. ) is an important agricultural crop in Minnesot a, where it is grown to enhance soil conservation, for green manure, for forage, and as a cash crop. Minnesota is now the third leading alfalfa producing state with 7 percent of the national acreage (2.0 million acres). The current value of the Minnesota alfalfa crop is estimated at $11 million. Alfalfa is cal led the queen of the forages because of it s longevity, high yield, and high nutritive value, It is grown over a wide range of 1atitudes fromthe tropics to the Canadian provinces. The ability of alfalfa to adapt to arid and humid environments and to regions having temperatures as high as 120°F or as lowas -83°F has resulted in its worldwide distribution. Four aspects of alfalfa in Minnesota are discussed in this bulletin: a bri ef history, growth characteristics, water relations, and the effect of climate on growth and yield. The info rmation cont ained in this bulletin comes from Minnesota-based studies and is for cultivars appropriate for the region. Research from other sources is also used to provide information not covered by Minnesota st udies. This environmental guide is intended to be of value in the application of alfalfa responses to the environment. Some relations may be of only local application (e.g., calendar days), whereas others have much broader appli cation (e.g., growing degree days and potential evapotranspi ration). The relations developed in this guide can be used to estimate alfalfa maturity, potential production at various stages of development, water use and irrigation requirements, and yields.