|Todd, Richard - Rick|
Submitted to: Journal of Range Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/5/2003
Publication Date: 5/3/2004
Citation: Todd, R.W., Guo, W., Stewart, B.A., Robinson, C. 2004. Vegetation, phosphorus, and dust gradients downwind from a cattle feedyard. Journal of Range Management. 57:291-299 Interpretive Summary: Most of the 7.5 million beef cattle produced on the southern High Plains are fed in feedyards with more than 5000 head. These concentrated feeding operations can potentially affect the local environment in many ways, including accumulation of manure, runoff from pens, and generation of dust and odors. Scientists noticed changes in the vegetation of a native shortgrass pasture directly downwind from a 25000-head beef cattle feedyar near Bushland, Texas, after it was stocked in 1970. Measurements of the vegetation in 2000 were compared with historical descriptions and measurements dating back to 1943. The historical vegetation of the pasture was dominated by desirable blue grama grass and buffalo grass. After 30 years, weedy annual grasses and forbs dominated the pasture closest to the feedyard and decreased with distance from the feedyard. Blue grama and buffalo grass were much reduced or eliminated closest to the feedyard and increased with distance from the feedyard. These changes were consistent with the response of shortgrass prairie vegetation to nitrogen fertilization. It was speculated that plant nutrients were carried from the feedyard to the pasture, probably with dust. Although the negative vegetation changes were dramatic close to the feedyard, they were limited in extent. Vegetation greater than 500 m from the feedyard was similar to historical vegetation.
Technical Abstract: Most of the 7.5 million beef cattle produced on the southern High Plains are fed in feedyards with >5000 head. Vegetation in a native shortgrass pasture adjacent to a 25000-head feedyard near Bushland Texas changed during 30 years after the feedyard was stocked. Objectives were to 1) describe historical vegetation of the pasture, 2) quantify current vegetation, and 3) determine vegetation changes with distance (D, m) upwin from the adjacent feedyard. We analyzed photographs, descriptions and measurements of vegetation back to 1943 to determine historical plant composition. Plant ground cover (C,%) and composition were quantified in twelve 90-m x 120-m plots using 50 randomly located 0.1 m2 quadrats in each plot in June and August 2000. Historical vegetation was dominated by blue grama [Bouteloua gracilis (H.B.K.]) Lag. ex Griffiths] and buffalograss [Buchloe dactyloides (Nutt.) Engelm.]. Annual grasses and forbs [mostly little barley (Hordeum pusillum Nutt.) and kochia (Kochia scoparia (L.)Schrad.)] dominated plots closest to the feedyard in 2000. Annual grass cover decreased with D (C=57.3-0.083D, r2=0.84). Annual forb cover decreased with D in June and August (C=39.5-0.067D r2=0.85). Perennial grasses were reduced or eliminated in plots closest to the feedyard. Perennial grass cover, mostly blue grama, increased with D in June and August (C=-4.4+0.044 D, r2=0.71). Blue grama cover was less than 4% closest to the feedyard, but was unchanged from 30 years ago (19%) more than 500 m from the feedyard, where cover was 17% in June and 23% in August. Although the negative vegetation changes were dramatic close to the feedyard, they were limited in extent. Vegetation greater than 500 m from the feedyard was similar to historical vegetation.