Productivity of Tall Wheatgrass and Great Basin Wildrye under Irrigation on a Greasewood-Rabbitbrush Range Site

Abstract

Nonbeneficial phreatophytes, greasewood and rubber rabbitbrush, in the Humboldt River Basin annually waste approximately 103,000 acre feet of water that could be used beneficially if forage species were established. After brushbeating, tall wheatgrass and Great Basin wildrye were spring seeded and established by sprinkler irrigation. Irrigation was continued for 3 to 5 years to induce root penetration into a capillary fringe so that grasses would persist as beneficial phreatophytes. After irrigation ceased, productivity of 115 to 710 lb/acre indicated that roots had not reached the capillary fringe and that continued irrigation was necessary to maintain production. Soil physical characteristics restricted root growth, and productivity with limited water or without water was reduced by chemical properties of a saline-sodic soil. Highest production of tall wheatgrass (4000 to 6000 lb/acre) and Great Basin wildrye (2400 to 2600 lb/acre) was obtained 3 years after seeding with weekly irrigations of 1.25 inches.