The cow-calf industry and water quality in South Florida, USA: a review

Abstract

Animal agriculture is often suggested as an important cause of water quality problems. This paper evaluates existing literature on the potential impacts of cow-calf production systems on water quality in South Florida, and provides a critical overview of the major gaps and limitations in the literature and present suggestions for future directions. Discrepancies in the literature suggest that there is a high degree of uncertainty associated with early estimates of the relative contribution of cowcalf operations to water quality problems in south Florida. Despite the extensive body of literature on this subject, limited information is available on the sources of P to the watershed and the relationship between land use, transport potential, water management, and climatic conditions controlling P loading. In addition, the relationships between urbanization, changes in land use, and potential impacts on water quality are important issues that have received little attention. Efforts should be placed on generating sound, science-based information about the real contribution of grazinglands to water quality issues.Maintaining and enhancing grazinglands and the natural resources associated with cow-calf ranches is essential to preserve Florida's unique ecosystems.

Grazing enhances belowground carbon allocation, microbial biomass, and soil carbon in a subtropical grassland

“…; Swain, Boughton, Bohlen, & Lollis, ): moderate‐density mostly continuous grazing during the summer growing season, and occasional utilization during the winter dormant period. Overall grazing intensity on the planted pastures is moderately high, about 0.6 ha/animal‐unit (Gene Lollis, ranch manager, personal communication ), but well within standard commercial ranges for south‐central Florida (Silveira et al., ). Four exclosures were established in a paired‐plot design in Bahiagrass pastures in 2002, and have since undergone various pathways of plant succession, with significant consequences for plant and soil carbon pools (J. Maki, unpublished data ), including succession to dominance of species other than Bahiagrass.…”

“…Grazing management in the pastures surrounding the grazing exclosures is representative of the ranch as a whole (e.g., Arthington et al 2007;Swain, Boughton, Bohlen, & Lollis, 2013): moderate-density mostly continuous grazing during the summer growing season, and occasional utilization during the winter dormant period. Overall grazing intensity on the planted pastures is moderately high, about 0.6 ha/animal-unit (Gene Lollis, ranch manager, personal communication), but well within standard commercial ranges for south-central Florida (Silveira et al, 2011). Sufficient Bahiagrass (i.e., at least three spatially distinct patches with area >1 m 2 ) remained in three out of the four exclosures to compare soil under Bahiagrass inside the exclosure to soil under Bahiagrass outside exclosures in grazed patches, and thus test for long-term impacts of grazing exclusion on SOC.…”

“…We focus specifically on the role of lignin as a proxy for plant tissue inputs in contributing to SOC (Thevenot, Dignac, & Rumpel, 2010). The soils in this study were extremely sandy (~97% sand), similar to the vast majority of pastureland in south-central Florida (Silveira, Obour, Arthington, & Sollenberger, 2011), and thus may have low capacity to physically stabilize SOC (Six, Conant, Paul, & Paustian, 2002;Stockmann et al, 2013). On the other hand, recent work on similar soils in south Florida has shown that the mineral-associated SOC fraction constitutes a disproportionate fraction of the total SOC, despite clay and silt accounting for only a few percent of mineral mass (Silveira, Xu, Adewopo, Franzluebbers, & Buonadio, 2014).…”

Nitrogen Fertilization and Proportion of Legume Affect Litter Decomposition and Nutrient Return in Grass Pastures

“…Each experimental unit was 20 ´ 48 m. One bahiagrass monoculture treatment received 0 kg N ha −1 (BG), and the other received 50 kg N ha −1 (BGN) in late spring to early summer to represent typical pasture fertilization management in Florida (Silveira et al, 2011). Each experimental unit was 20 ´ 48 m. One bahiagrass monoculture treatment received 0 kg N ha −1 (BG), and the other received 50 kg N ha −1 (BGN) in late spring to early summer to represent typical pasture fertilization management in Florida (Silveira et al, 2011).…”

Soil‐Fertility Principles for Warm‐Season Perennial Forages and Sustainable Pasture Production

“…Research in Florida reported stargrass yield responses to N application of 200 to 400 kg N ha −1 year −1 (Mislevy et al, 1989a, 1989b) Although yields may increase with higher rates of N, application of high levels of N is probably neither economic nor environmentally sustainable in most forage‐based animal production systems. At present, levels of approximately 50 to 60 kg N ha −1 are typically applied to established grass swards in Florida (Silveira et al, 2011a). Higher N levels (up to 80 kg ha −1 harvest −1 ) are often associated with intensive hay production systems (Mylavarapu et al, 2012).…”