Submitted to: Agricultural Research Service Publication
Publication Type: Other
Publication Acceptance Date: 4/1/2002
Publication Date: 6/10/2002
Citation: Sigua, G.C. 2002. Cattle grazing and the environment. USDA-Agricultural Research Service STARS Field Day Manual, Brooksville, Florida. p. 40-42. Interpretive Summary:
Technical Abstract: Maintaining a balance between the amount of nutrients added to the soil as manure and fertilizer and the amount of nutrients removed as forages, hay, or livestock is critical for productive crop growth and water/environmental quality protection. Soil fertility levels over a 15-year period (1988-2002) were compared to evaluate the long-term effects of differing fertility (phosphorus (P) or no P) and management treatments (grazed only or grazed and hayed) on soil P and other soil nutrients in subtropical beef cattle pastures planted with either bahiagrass (BG) or rhizoma peanut - mixed grass (RP-G) association. The levels of soil P and other soil nutrients were significantly affected by pasture management (P = 0.001). Environmentally, levels of soil nutrients in beef cattle pastures are declining. During the past 15 years, average soil test values for P, potassium, calcium and magnesium have declined by about 32, 51, 61 and 58%, respectively. Phosphorous levels in the grazed only bahiagrass pastures were essentially unchanged after 15 years without P fertilization. The combination of grazing in spring and haying in early fall can be considered a good pasture management (i.e., BMP) in maintaining nutrient balance in the pasture fields, thereby avoiding the potential negative impact to the environment. Overall, there was no spatial and temporal build up of soil P and other soil nutrients despite the annual application of P-containing fertilizers in RP-G and daily in-field loading of animal waste. Results of this study have brought up a renewed focus on improving the fertilizer efficiency in subtropical beef cattle ecosystems, with a goal to establish a balance of nutrients removed and nutrients added either through fertilizer or through recycling to the pasture fields.