Infiltration and Sediment Production on a Deep Hardland Range Site in North Central Texas

Abstract

Greatest infiltration rate and lowest sediment production most closely associated with variations in infiltration capacity and occurred in the honey mesquite canopy zone. Infiltration on sediment production. shortgrass interspace areas was about one-half of the canopy zone rate. Terminal infiltration rates within the canopy zone and Study Area shortgrass interspace areas were affected little by brush control treatments. Infiltration rate improvement due to treatment occurred primarily in the midgrass interspace areas. Water-stable aggregates and the interaction of soil aggregate stability with the amount of bare ground were the dominant factors controlling infiltration. Sediment production on the shortgrass interspace was double that of the canopy zone or midgrass interspace areas. Low rate of sediment production on the midgrass interspace areas occurred on areas aerially sprayed or root plowed 3 years earlier. Sediment production was controlled primarily by an interaction of soil organic matter and amount of above-ground biomass or grass cover. Past land management practices have resulted in large increases of honey mesquite (PTosopis glandulosa Torr. var. glandulosa) which now occurs on 56 million acres of Texas rangeland, including 34 million acres which are moderately to heavily infested (Fisher et al. 1973). Most of the heavily and moderately infested rangelands currently produce much less forage than their potential and require control of the honey mesquite to improve forage production. Herbicides and root plowing are widely accepted tools for improving honey mesquite dominated rangelands. However, little information exists for Texas rangelands relative to the impact of honey mesquite control on infiltration rates and sediment production. In other areas, brush control practices have apparently increased infiltration rates and decreased erosion (Rosa and Tigerman 1951, Rich 1961, Rowe and Reimann 1961, Dragoun 1969, Blackbum and Skau 1974). Yet, in some cases, these practices have failed to improve watershed condition (Rowe and Reimann 1961, Blackburn and Skau 1974, Gifford and Busby 1974). Blackburn (1975) reported sagebrush (Artemesia spp.) canopy zones to have exceedinalv high infiltration rates. sometimes 3 to 4 Field research was conducted on the W.T. Waggoner Estate southwest of Vernon, Texas. Theestate is part of the Rolling Plains land resource area which comprises approximately 6.32 million ha of rolling to rough topography in northwest Texas (Gould 1975). Normal annual precipitation for Vernon, Texas, is about 65 cm, with May, June, and October being the months of highest precipitation and January being the driest month (USDC 1976). The average frost-free period is 232 days (Koos et al. 1962). Climax vegetation of the Rolling Plains include tall and midgrasses, but continuous heavy utilization by cattle has reduced the vegetation to primarily short and midgrasses with varying densities of woody plants. Honey mesquite, with a mean height of 1.6 m, a mean density of 437 plants/ ha and a 21% canopy cover, dominated the study area prior to treatment. Lotebush (Ziziphus obrusifolia (T.G.) Gray), tasajillo (Opuntia leprocaulis D.C. var leptocaulis), and grassland prickly pear (Opuntia rnacrorhiza Engelm.) were common on the study area. Herbaceous vegetation was typified by Texas wintergrass (Sripa feucotricha Trin. and Rupr.), Arizona cottontop (Digitaria calryornica (Benth.) Henr.), little barley(Hordeum pusillum (Nutt.)), rescuegrass (Bromus unioloides (Willd.) H.B.K.), buffalograss (Buchloe dacfyloides (Nutt.) Engelm.), sand dropseed (Sporobolus cryptandrus (Torr.) Gray), and purple threeawn (Aristida purpurea (Nutt.)).