Nitrogen Fertilization of Irrigated Russian‐Thistle Forage. II. Some Nutritional Qualities1

Abstract

AbstractRussian‐thistle (Salsola spp.), a widely dispersed weed of the western U.S., has been used occasionally as an emergency forage during periods of drought. Because of its known water use efficiency and the growing demand upon irrigation water resources, several of the nutritional qualities of Russian‐thistle have been examined under irrigated field conditions to evaluate its potential as a forage crop for arid and semiarid regions. Plants were grown in the field with a total water application of 22 to 28 cm: urea levels corresponding to 0, 28, 56, 112, and 224 kg N/ha were applied. Water content was found to be similar to that of other species commonly used as forage and was minimally affected by N application. Crude protein, acid detergent lignin, and acid detergent fiber content were slightly but significantly affected by N application. These latter three parameters, however, varied strongly with stage of maturity. Average values of crude protein, acid detergent lignin, and acid detergent fiber were 22, 20, and 4%, respectively, for the youngest plants and 10, 33, and 7%, respectively, for the oldest plants. The protein had an amino acid composition which was nutritionally well balanced. At 112 and 224 kg N/ha plants had average nitrate levels of 0.5 to 0.6%, although variability in measured levels was large.