| Fernando A. Ibarra-F., Jerry R. Cox, Martha H. Martin-R., Todd A. Crowl and Christopher A. Call |
| Ibarra-F. and Martin-R. are graduate students, Range Science Department, Utah State University and USDA-Agricultural research Service, Forage and Range Research Laboratory, Utah State University, Logan, UT., 84322-6300. Both are permanently stationed at Centro de Investigaciones Pecuaries del Estato de Sonora, Apdo Postal 1754, Hermosillo, Sonora, Mexico; Cox is resident director of research and range extension specialist, Texas A&M University, Agricultural Research and ExtensionCenter, Vernon, TX., 76385. When this research was initiated, Cox was a range scientist with USDA-ARS Research Service in Tucson, AZ and Logan, UT; Crowel is assistan professor, Ecology Center and Department of Fisheries and Wildlife and Watershed Science Unit, Utah State University, Logan, UT., 84322-5210; and Call is associate professor, Range Science Department,Utah State University, Logan, UT., 84322-5230. |
Abstract |
| This research was designed to identify relationships between T-4464 buffelgrass (Cenchrus ciliaris L.) survival and climatic and soil characteristics. At 167 buffelgrass seeding sites in North America we collected climatic and soils data where the grass: 1) persisted over time and increased in area covered (spreads), 2) persisted over time but does not increase in area covered (persists), and 3) declined over time and all plants eventually died (dies). At 30 sites in Kenya we collected climatic and soils data in the area where T-4464 seed was originally collected. Only total soil nitrogen and organic carbon differed among survival regimes. Total soil nitrogen and organic carbon concentrations were least where buffelgrass spreads, intermediate where the grass persists and greatest where the grass dies. To predict buffelgrass survival among the 3 survival regimes, and between areas where the grass spreads or dies, we used discriminant function analyses. A model including organic carbon, total soil nitrogen, sand, clay, potassium and cation exchange capacity correctly classified 78% (r2=0.8) of the seeding sites in the 3 survival regimes. A model including sand, total soil nitrogen, calcium, mean minimum temperature in the coldest month, annual precipitation and winter precipitation correctly classified 88% (r2=0.8) of the seeding sites between spreads and dies. Survival regime selection prior to brush control, seedbed preparation and sowing will reduce planting failure probabilities, soil erosion and economic losses, and enhance long-term beef production. |
| Key Words: Cenchrus ciliarus, range seeding, climate, soil nutrients, Mexico, Texas, Kenya. |