FORAGES - CHAPTER 19

Authors: Jensen, Kevin; HILL, ROBERT - UTAH STATE UNIV.; Waldron, Blair; Peel, Michael

Submitted to: American Society of Agronomy Monograph Series
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/3/2005
Publication Date: 1/10/2007
Citation: Jensen, K.B., Hill, R.W., Waldron, B.L., Peel, M. 2007. Forages. In: Lascano, R.E., and R.E. Sojka (eds). Irrigation of Agricultural Crops, 2nd ed., Agronomy Monograph Series No. 30. p. 363-393. Madison, WI.

Interpretive Summary: Water use by forage crops is an important component of water management in the western United States where it constitutes a significant proportion of the irrigated land. Forage crops account for 57 percent of the total irrigated area in the eight western states of Colorado, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, and Wyoming. Plant growth in most of these areas is frequently limited by the lack of soil water during later portions of the growing season. Proper irrigation of pastures requires an understanding of pasture management practices such as grazing, fertilizer application, and weed control to maximize pasture production. Alfalfa is the most important forage crop grown under irrigation in the U.S. Other legume species commonly grown under irrigation for forage production include birdsfoot trefoil, white clover, red clover, and kura clover, and occasionally cicer milkvetch, and sainfoin. Pasture grasses such as tall fescue, perennial ryegrass, orchardgrass, and meadow brome have higher water requirements than smooth brome and intermediate wheatgrass. This chapter focuses on the effects of different levels of irrigation on plant development, yield, forage quality, and use of water on forage grasses and legumes.

Technical Abstract: Water use by forage crops is an important component of water management in the western United States where it constitutes a significant proportion of the irrigated land. Forage crops account for 57 percent of the total irrigated area in the eight western states of Colorado, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, and Wyoming. Plant growth in most of these areas is frequently limited by the lack of soil water during later portions of the growing season. Forage plants that have adaptations that allow them to maintain plant growth under water-limiting conditions are critical to maintaining a constant source of forage throughout the growing season. Proper irrigation of pastures requires an understanding of fundamental plant, water, and soil plant relationships. In addition, irrigation must be coordinated with other pasture management practices such as grazing, fertilizer application, and weed control to maximize pasture production. Alfalfa (Medicago sativa L.) is undoubtedly the most important forage crop grown under irrigation in the U.S. Other legume species commonly grown under irrigation for forage production include birdsfoot trefoil (Lotus corniculatus L.), Trifolium species including white clover (T. repens L.), red clover (T. pratense L.), and kura clover (T. ambigum M. Bieb.), and occasionally cicer milkvetch (Astragulus cicer L.), and sainfoin (Onobrychis viciifolia Scop.). White, red, and kura clovers, birdsfoot trefoil, sainfoin, and cicer milkvetch are grown as a forage under irrigation or limited irrigation. Pasture grasses such as tall fescue (Festuca arundinacea Schreb.), perennial ryegrass (Lolium perenne L.), orchardgrass (Dactylis glomerata L.), and meadow brome (Bromus riparius Rehm.) have higher water requirements than smooth brome (Bromus inermis Leyss.) and intermediate wheatgrass (Thinopyrum intermdium (Host) Barkworth & D.R. Dewey). This chapter focuses on the effects of different levels of irrigation on vegetative development, dry matter yield, nutritional quality, and water-use efficiency on forage grasses and legumes.