Rangeland grasses are difficult to establish on sandy soils because blowing sand can kill young seedlings. Four grass species, sideoats grama [Bouteloua curtipendula (Michx.) Torr.], cane bluestem [Bothriochloa barbinodis (Lag.) Herter], green sprangletop [Leptochloa dubia (H.B.K.) Nees], and sand bluestem (Andropogon hallii Hack.) were grown in a greenhouse and subjected to wind and wind with sand in a laboratory wind tunnel. The blowing sand killed the seedlings or retarded their growth, but wind alone had little influence. With increasing age, the young grass plants became more tolerant to wind and sand damage. Plant growth was slowed because the blowing sand ruptured plant cells, dried out the exposed tissue, and exposed the damaged seedlings to diseases and insects.

The purpose of the study was to evaluate 3 strains of switchgrass (Panicum virguturn L.) under 3 water and 3 harvest regimes. Dry matter yields, under natural rainfall and full irrigation, averaged 2.0 and 6.7 metric tons/ha, respectively. Productivity of the 3 strains ranked G 3OO>HV-341>Biackweii. Yields of HV-341 and Blackwell were similar under 1,2, or 3 harvests per year but those of G-300 were reduced by 2 or 3 harvests. Switchgrass forage contained about 10.8% crude protein (CP) and 0.23% P in late June. In November, previously unclipped forage contained 4.3% CP and 0.12% P, while that clipped twice contained 5.5% CP and 0.15% P. Maximum production was obtained with 116.5 cm of water use but maximum water use effhziency was obtained with about 85.5 cm of water use (rainfall f irrigation + soil water), The switchgrasses are adapted for use both without irrigation and when varying amounts of irrigation water are availbie. G-300 yielded more and produced earlier and later than the other two strains thus it may be the best choice for use for rangeimprovement or for irrigated pastures. However, it requires careful management because it is more susceptible to overuse than the other two strains. Switchgrass (Panicurn virgatum L.) is a perennial tallgrass adapted to the diverse climate and soils of the mid-continent and is widely distributed throughout the United States (Hitchcock) 1951). It is a productive warm-season forage-grass used primarily for summer grazing, and is most abundant on sandylands of the remaining natural grasslands of the Great Plains. Adapted strains and varieties are used in pure stands or in mixtures with other warm-season prairie grasses for range, pasture, and conservation plantings. In the Southern High Plains, yields of upland native rangeland were estimated to be from 730 to 1,120 kg/ ha on deep sand sites (Wilhite 1965), and from 2,240 to 2,575 kg/ ha on sandhill sites with more favorable plant-soil-water relations (Wilhite 1959). Most of these sites are now producing much less than their potential because of deteriorated range condition. Forage quality is an essential criterion in the selection and management of forage for livestock consumption. Phosphorus and protein are the most deficient components in livestock nutrition in the southwest. Crude protein in Texas range grasses decreases duringthe growing season and is not closely related to soil nitrogen content (Fudge and Fraps 1945). In Northwest Texas the phosphorus content of forage was sufficient for range cattle in 66% of the grasses early in the growing season but deficient in 91% of the grasses at maturity (Fudge and Fraps 1945). Average protein content of short and mid-grasses of the southern mixed prairie in Texas seldom meet the protein requirements of beef cows (Rogers and BOX 1967). Performance with limited moisture is of primary concern in evaluating and selecting superior forage plants. Water-use efficiency (forage production/unit of water) is of prime importance in Authors are soil scientist, U.S. Dep. Agr., Big Spri...

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The assistance of Howard Taylor and James E. Box, Jr., SWC, in planning the study, and the help and advice of Richard Dudley, AERD, in chiseling the plots is appreciated.

Clipping shortgrass range in Texas at 2-week intervals gave 94% more forage yield than fall harvest. Clipping treatments had little effect on ground cover and plant composition. Yield was shown to be a function of current season precipitation, while plant composition and ground cover were more closely related to previous season precipitation. In the one of seven seasons when stored soil water was available at the beginning of the growing seasdn (4.91 inches of plant-available water), it was depleted by June 15.