The influence of precipitation and grazing upon black grama grass range

TitleThe influence of precipitation and grazing upon black grama grass range
Publication TypeReport
Year of Publication1934
AuthorsNelson E.W
Series TitleUSDA Technical Bulletin No. 409
Date PublishedApril 1934
Keywordsblack grama, government publication, grazing, overgrazing, precipitation, range forage
AbstractThe excellent stand and growth of palatable perennials that once covered much of the semiarid rangelands of the Southwest afforded abundant feed for a thriving livestock industry. Where such conditions still prevail and management is adjusted to sustain production of feed within the limits of climatic conditions, livestock production is effective. On most of the range, however, continued over-stocking and the consequent accumulation of ill effects of overgrazing, combined with recurring drought, have brought about conditions involving not only heavy losses to the livestock producer but even a complete failure of profitable production. How to restore the productivity of these lands is an urgent question and one with many ramifications. One very important consideration is the preservation of the best of the remaining forage and the extension of its present growth. In this connection, one species of perennial grass growing on a considerable part of the semidesert range deserves primary attention. This is both because of its high palatability and its ability to extend its growth abundantly under moderately favorable circumstances, in which particulars black grama (Bouteloua eriopoda) is without a peer. Originally, black grama was the mainstay of the range, occurring rather abundantly and in almost a pure type over extensive areas of southeastern Arizona, southern New Mexico, western Texas, and south into Mexico. As such stands deteriorated, black grama died out to a considerable degree, but the plant still occurs as important range forage on extensive areas either in almost pure stands or mixed with other perennial grass species. Black grama is characteristically drought resistant, a quality indispensable to the maintenance of any range forage plant under the climatic conditions prevailing in the Southwest. It is highly palatable and nutritious both in summer and winter, making it a valuable year-long forage plant, especially for cattle. During some winters, the stems remain green up to about the second node from the top, and clusters of leaves may come out at the nodes the following spring. Black grama ordinarily cures well on the stalk and retains its nutritive value through the dry spring period when other range forage is parched and harsh. Although the plant can withstand recurrent grazing by livestock, too heavy utilization impairs its vigor. During drought periods, plants so weakened succumb, thereby greatly depleting the stand. It is of the greatest importance, therefore, to know just what degree of grazing use can be applied without injury to black grama ranges. This bulletin presents the results 13 years of study (1915 to 1927, inclusive) of the influence of the variable precipitation and several intensities of grazing on the black grama range type on the Jornada Experimental Range (formerly Jornada Range Reserve) and adjacent public domain range in southern New Mexico. The adoption on southwestern ranges of such principles as this study has brought to light should make the range cattle business of the region much more stable and profitable.