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S W Coleman - One of the best experts on this subject based on the ideXlab platform.
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Absence of negative environmental effects of increased soil P levels in cattle congregation zones
Agronomy for Sustainable Development, 2012Co-Authors: Gilbert C. Sigua, Chad C. Chase, S W Coleman, Joseph AlbanoAbstract:Determining soil nutrient distribution in pasture with beef cattle Operation is critical to identifying which area is at risk of nitrogen or phosphorus buildup and loading. Characterizing spatial variability of soil nutrients in relations to landscape location is important for understanding the effects of future land use change on soil nutrients and water pollution. We hypothesized that cattle congregation site may have higher concentrations of phosphorus and nitrogen than in the pasture and grazing site or the adjoining forest site. This study assessed levels of Mehlich-1 extractable P, total inorganic N, and soil P saturation in relation to landscape locations in subtropical beef cattle pasture. Soil samples were collected during the spring and fall of 2005 to 2007 from three 19 adjoining landscape sites that are associated with beef cattle Operation. These sites consisted of three locations: congregation, grazing, and forest sites. The levels of extractable P, total inorganic N, and P saturation in soils varied with landscape location. Congregation site had the highest concentration of extractable P of 36.1 mg kg^−1, followed by grazing site of 17.7 mg kg^−1, and forest site of 8.2 mg kg^−1. Spatial distribution of total inorganic nitrogen across the landscape was higher for congregation site (2.3 mg kg^−1) than forest site (0.9 mg kg^−1) and grazing site (0.7 mg kg^−1). The overall spatial distribution of extractable P from congregation site to forest site can be described by P = −4.2 x + 45.8; ( R ^2 = 0.97**); the best-fit models for total inorganic N was 0.04 x ^2 − 0.6 x + 3.5; ( R ^2 = 0.89**) and for soil P saturation was −3.6 x + 36.2; ( R ^2 = 0.92**). Results show that the levels of extractable P, total inorganic nitrogen, and soil phosphorus saturation were decreasing from the congregation site to forest site. Although our results may have had supported our hypothesis that congregation site typical on Florida ranchers have greater concentrations of extractable P than in grazing site and forest site, the average extractable P at all three landscape locations did not exceed the crop requirement threshold of 36 mg kg^−1 and the water quality protection threshold of 150 mg kg^−1. Our current pasture management including cattle rotation in terms of grazing days and current fertilizer application had thus no negative environmental impact on landscape with cow–calf Operation.
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spatial distribution of soil carbon in pastures with cow calf Operation effects of slope aspect and slope position
Journal of Soils and Sediments, 2010Co-Authors: Gilbert C. Sigua, S W ColemanAbstract:The rate at which soil carbon (C) accumulates in terrestrial beef agro-ecosystem is uncertain, as are the mechanisms responsible for the current C sink. Broad knowledge of cattle movement in pasture situations is critical to understanding their impact on agro-ecosystems. Movement of free-ranging cattle varies due to spatial arrangement of forage resources within pastures and the proximity of water, mineral feeders, and shades to grazing sites. The effects of slope aspect (SA) and slope position (SP) on nutrient dynamics in pastures are not well understood. Few studies have been made of soil-vegetation and soil-landscape relationships along an elevation gradient in tropical and subtropical regions. Current literature suggests no clear general relationships between grazing management and nutrient cycling. Early study reported no effect of grazing on soils nutrients, while other studies determined increases in soil nutrients due to grazing. We hypothesize that SA and SP could be of relative importance in controlling spatial variability of soil organic carbon (SOC). This study addressed the effects of SA and SP on the spatial distribution of SOC in forage-based pastures with Cow-Calf Operation in subtropical region of southeastern USA. Soil samples were collected at 0–20 and 20–40 cm on contiguous south-, north-, east-, and west-facing slopes across different landscape positions (top slope, middle slope, and bottom slope) of 100 ha pastures during three summer seasons (2004–2006). Soil samples were air-dried, passed through a 2-mm mesh sieve, and visible roots were removed prior to analyses of SOC and other soil properties likely to affect spatial distribution of SOC. Analyses of soils were conducted at the Subtropical Agricultural Research Station in Brooksville, FL, following the dry-ash or the ‘loss-on-ignition’ method. Concentrations of organic carbon in soils from four different SA, three SP, and two soil depths (SD) in 2004, 2005, and 2006 were analyzed statistically following a four-way analysis of variance using the SAS PROC general linear model. There was an SA × SP interaction (p ≤ 0.0001) effect on the concentration of SOC. The two highest concentrations of SOC were observed from top slope (8.4 g kg−1) and middle slope (7.8 g kg−1) in south-facing slope, and the two lowest levels of SOC were in top slope (2.6 g kg−1) and middle slope (3.0 g kg−1) of north-facing slope, respectively. Soil C also varied significantly among SA (p ≤ 0.0001), SP (p ≤ 0.001), and SD (p ≤ 0.0001). Averaged across years and SP, soils on the south-facing slope contained the greatest amount of SOC, while soils on the north-facing slope had the least amount of SOC. Average concentrations of SOC in top slope and middle slope were comparable. These values were significantly (p ≤ 0.05) higher when compared with soils from bottom slope. About 73% of SOC spatial variability could be explained by total clay content. Concentrations of SOC were quadratically (SOC = 0.05 × clay2 − 0.29 × clay + 4.4; p ≤ 0.001) related with total clay content. No other significant correlations between SOC and other soil properties were found. Our results have shown that soils on the south-facing slope had greatest concentration of SOC, while soils on the north-facing slope had the lowest concentration of SOC. The differences may be attributed to topographic aspect-induced microclimatic differences, which are causing differences in the biotic soil component and SOC trend. SA may be acting as an important topographic factor influencing local site microclimate mainly because it determines the amount of solar radiation received. Differences in microclimate are often linked to varying soil moisture and erosion potential and in turn could be used to explain distribution of plant communities. The north-facing slope had the lower forage availability when compared with the south-facing slope. There was a decreasing trend in the average forage availability with decreasing slope. Between the top slope and the bottom slope, forage availability declined from 2,484 to 1,448 kg ha−1, which can be attributed to more grazing activities of cattle at bottom slope. Differences in SOC among different SA and SP could also be explained by varying amount of total clay. Concentrations of SOC were linearly related with increasing total clay content. The greatest amount of SOC was observed from soils located at the top slope of south-facing slope. Of the entire SA, south-facing slope had the greatest concentration of total clay, while the greatest clay content among SP was observed from the top slope. Results further revealed that 73% of SOC spatial variability could be explained by total clay content. The relationship between SOC and total clay content was best described by a quadratic equation: SOC = 0.05 × clay2 − 0.29 × clay + 4.4; R 2 = 0.73; p ≤ 0.001. Results of our study are suggesting that SA and SP could be of relative importance in controlling spatial variability of SOC. Averaged across years, soils on the south-facing slope contained the greatest amount of SOC, while soils on the north-facing slope had the least amount of SOC. Based on the average concentration of SOC, the south-facing slope may have sequestered about 6,460 kg ha−1 of SOC. Results have shown that landscape attributes (e.g., SA and SP) associated with beef cattle pastures as a part of the agro-ecological system could be potential sink for C sequestration, thus reducing atmospheric carbon dioxide concentrations. It is still critical to understand how the interactions of pasture management and landscape are affecting soil C dynamics. More studies are needed to assess the rate at which soil C is accumulating as well as the mechanisms responsible for the current and future C sink in forage-based pastures with Cow-Calf Operations.
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Spatial distribution of soil carbon in pastures with Cow-Calf Operation: effects of slope aspect and slope position
Journal of Soils and Sediments, 2010Co-Authors: Gilbert C. Sigua, S W ColemanAbstract:Background, aim, and scope The rate at which soil carbon (C) accumulates in terrestrial beef agro-ecosystem is uncertain, as are the mechanisms responsible for the current C sink. Broad knowledge of cattle movement in pasture situations is critical to understanding their impact on agro-ecosystems. Movement of free-ranging cattle varies due to spatial arrangement of forage resources within pastures and the proximity of water, mineral feeders, and shades to grazing sites. The effects of slope aspect (SA) and slope position (SP) on nutrient dynamics in pastures are not well understood. Few studies have been made of soil-vegetation and soil-landscape relationships along an elevation gradient in tropical and subtropical regions. Current literature suggests no clear general relationships between grazing management and nutrient cycling. Early study reported no effect of grazing on soils nutrients, while other studies determined increases in soil nutrients due to grazing. We hypothesize that SA and SP could be of relative importance in controlling spatial variability of soil organic carbon (SOC). This study addressed the effects of SA and SP on the spatial distribution of SOC in forage-based pastures with Cow-Calf Operation in subtropical region of southeastern USA. Materials and methods Soil samples were collected at 0–20 and 20–40 cm on contiguous south-, north-, east-, and west-facing slopes across different landscape positions (top slope, middle slope, and bottom slope) of 100 ha pastures during three summer seasons (2004–2006). Soil samples were air-dried, passed through a 2-mm mesh sieve, and visible roots were removed prior to analyses of SOC and other soil properties likely to affect spatial distribution of SOC. Analyses of soils were conducted at the Subtropical Agricultural Research Station in Brooksville, FL, following the dry-ash or the ‘loss-on-ignition’ method. Concentrations of organic carbon in soils from four different SA, three SP, and two soil depths (SD) in 2004, 2005, and 2006 were analyzed statistically following a four-way analysis of variance using the SAS PROC general linear model. Results There was an SA × SP interaction ( p ≤ 0.0001) effect on the concentration of SOC. The two highest concentrations of SOC were observed from top slope (8.4 g kg^−1) and middle slope (7.8 g kg^−1) in south-facing slope, and the two lowest levels of SOC were in top slope (2.6 g kg^−1) and middle slope (3.0 g kg^−1) of north-facing slope, respectively. Soil C also varied significantly among SA ( p ≤ 0.0001), SP ( p ≤ 0.001), and SD ( p ≤ 0.0001). Averaged across years and SP, soils on the south-facing slope contained the greatest amount of SOC, while soils on the north-facing slope had the least amount of SOC. Average concentrations of SOC in top slope and middle slope were comparable. These values were significantly ( p ≤ 0.05) higher when compared with soils from bottom slope. About 73% of SOC spatial variability could be explained by total clay content. Concentrations of SOC were quadratically (SOC = 0.05 × clay^2 − 0.29 × clay + 4.4; p ≤ 0.001) related with total clay content. No other significant correlations between SOC and other soil properties were found. Discussion Our results have shown that soils on the south-facing slope had greatest concentration of SOC, while soils on the north-facing slope had the lowest concentration of SOC. The differences may be attributed to topographic aspect-induced microclimatic differences, which are causing differences in the biotic soil component and SOC trend. SA may be acting as an important topographic factor influencing local site microclimate mainly because it determines the amount of solar radiation received. Differences in microclimate are often linked to varying soil moisture and erosion potential and in turn could be used to explain distribution of plant communities. The north-facing slope had the lower forage availability when compared with the south-facing slope. There was a decreasing trend in the average forage availability with decreasing slope. Between the top slope and the bottom slope, forage availability declined from 2,484 to 1,448 kg ha^−1, which can be attributed to more grazing activities of cattle at bottom slope. Differences in SOC among different SA and SP could also be explained by varying amount of total clay. Concentrations of SOC were linearly related with increasing total clay content. The greatest amount of SOC was observed from soils located at the top slope of south-facing slope. Of the entire SA, south-facing slope had the greatest concentration of total clay, while the greatest clay content among SP was observed from the top slope. Results further revealed that 73% of SOC spatial variability could be explained by total clay content. The relationship between SOC and total clay content was best described by a quadratic equation: SOC = 0.05 × clay^2 − 0.29 × clay + 4.4; R ^2 = 0.73; p ≤ 0.001. Conclusions Results of our study are suggesting that SA and SP could be of relative importance in controlling spatial variability of SOC. Averaged across years, soils on the south-facing slope contained the greatest amount of SOC, while soils on the north-facing slope had the least amount of SOC. Based on the average concentration of SOC, the south-facing slope may have sequestered about 6,460 kg ha^−1 of SOC. Recommendation and perspectives Results have shown that landscape attributes (e.g., SA and SP) associated with beef cattle pastures as a part of the agro-ecological system could be potential sink for C sequestration, thus reducing atmospheric carbon dioxide concentrations. It is still critical to understand how the interactions of pasture management and landscape are affecting soil C dynamics. More studies are needed to assess the rate at which soil C is accumulating as well as the mechanisms responsible for the current and future C sink in forage-based pastures with Cow-Calf Operations.
Gilbert C. Sigua - One of the best experts on this subject based on the ideXlab platform.
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Phosphorus Dynamics and Management in Forage Systems with Cow-Calf Operation
Sustainable Agriculture Reviews, 2015Co-Authors: Gilbert C. SiguaAbstract:Phosphorus fertilization is a vital component of productive farming. Phosphorus is an essential macronutrient that is required to meet global food requirements and make crop and livestock production profitable. While adequate levels of phosphorus in the soil are essential to grow crops, phosphorus has the potential to induce eutrophication in our water systems. Controlling phosphorus inputs is the thus considered the key to reducing eutrophication and managing ecological integrity. Forage-based Cow-Calf Operations may have detrimental impacts on the chemical status of groundwater and streams and consequently on the ecological and environmental status of surrounding ecosystems. Relatively, little information exists regarding possible magnitudes of phosphorus losses from grazed pastures. Whether or not phosphorus losses from grazed pastures are significantly greater than background losses and how these losses are affected by soil, forage management, or stocking density are not well understood. The goal of this paper is to demonstrate the various effects of differing pasture fertility, animal behavior, and grazing management systems on the levels and changes of soil P in subtropical beef cattle pastures that will improve our understanding of P dynamics, cycling, and management in the agroecosystem. From our Florida experience perspectives, the following critical results are worthwhile mentioning: (1) environmentally, soil phosphorus in Florida pastures are declining; (2) soil phosphorus in pasture fields with no phosphorus fertilization were consistently lower than those of the fertilized fields by about 49.1 % to 40.9 % from 1988 to 2000, respectively; (3) soil phosphorus concentrations in 1988 of about 94.1 mg kg−1 and in 2000 of about 69.2 mg kg−1 were not high enough to be of environmental concern, so annual additions of phosphorus-fertilizer would be still practical to sustain plant and animal productivity in subtropical beef cattle pastures; (4) congregation zones in pastures with beef cattle Operations in three regions of Florida are not phosphorus-rich, therefore may not contribute more phosphorus to surface and groundwater supply; and (5) slope aspect and slope position could be of relative importance in controlling spatial distribution of soil phosphorus. Effective use and cycling of phosphorus therefore is critical for pasture productivity and environmental stability in subtropics. This will help to renew the focus on improving inorganic fertilizer efficiency in subtropical beef cattle systems, and maintaining a balance of phosphorus removed to phosphorus added to ensure healthy forage growth and minimize phosphorus runoff. Additionally, if the overall goal is to reduce phosphorus losses from animal-based agriculture then there is a crucial need to balance off-farm phosphorus inputs in feed and fertilizer with outputs to the environment. Consequently, this paper has provided fundamental information on the source and transport control strategies that can provide the basis to increase phosphorus efficiency in agroecosystem with Cow-Calf Operation.
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Groundwater phosphorus in forage-based landscape with Cow-Calf Operation
Environmental Monitoring and Assessment, 2014Co-Authors: Gilbert C. Sigua, Chad C. ChaseAbstract:Forage-based Cow-Calf Operations may have detrimental impacts on the chemical status of groundwater and streams and consequently on the ecological and environmental status of surrounding ecosystems. Assessing and controlling phosphorus (P) inputs are, thus, considered the key to reducing eutrophication and managing ecological integrity. In this paper, we monitored and evaluated P concentrations of groundwater (GW) compared to the concentration of surface water (SW) P in forage-based landscape with managed Cow-Calf Operations for 3 years (2007–2009). Groundwater samples were collected from three landscape locations along the slope gradient (GW1 10–30 % slope, GW2 5–10 % slope, and GW3 0–5 % slope). Surface water samples were collected from the seepage area (SW 0 % slope) located at the bottom of the landscape. Of the total P collected (averaged across year) in the landscape, 62.64 % was observed from the seepage area or SW compared with 37.36 % from GW (GW1 = 8.01 %; GW2 = 10.92 %; GW3 = 18.43 %). Phosphorus in GW ranged from 0.02 to 0.20 mg L^−1 while P concentration in SW ranged from 0.25 to 0.71 mg L^−1. The 3-year average of P in GW of 0.09 mg L^−1 was lower than the recommended goal or the Florida’s numeric nutrients standards (NNS) of 0.12 mg P L^−1. The 3-year average of P concentration in SW of 0.45 mg L^−1 was about fourfold higher than the Florida’s NNS value. Results suggest that Cow-Calf Operation in pasture-based landscape would contribute more P to SW than in the GW. The risk of GW contamination by P from animal agriculture production system is limited, while the solid forms of P subject to loss via soil erosion could be the major water quality risk from P.
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Absence of negative environmental effects of increased soil P levels in cattle congregation zones
Agronomy for Sustainable Development, 2012Co-Authors: Gilbert C. Sigua, Chad C. Chase, S W Coleman, Joseph AlbanoAbstract:Determining soil nutrient distribution in pasture with beef cattle Operation is critical to identifying which area is at risk of nitrogen or phosphorus buildup and loading. Characterizing spatial variability of soil nutrients in relations to landscape location is important for understanding the effects of future land use change on soil nutrients and water pollution. We hypothesized that cattle congregation site may have higher concentrations of phosphorus and nitrogen than in the pasture and grazing site or the adjoining forest site. This study assessed levels of Mehlich-1 extractable P, total inorganic N, and soil P saturation in relation to landscape locations in subtropical beef cattle pasture. Soil samples were collected during the spring and fall of 2005 to 2007 from three 19 adjoining landscape sites that are associated with beef cattle Operation. These sites consisted of three locations: congregation, grazing, and forest sites. The levels of extractable P, total inorganic N, and P saturation in soils varied with landscape location. Congregation site had the highest concentration of extractable P of 36.1 mg kg^−1, followed by grazing site of 17.7 mg kg^−1, and forest site of 8.2 mg kg^−1. Spatial distribution of total inorganic nitrogen across the landscape was higher for congregation site (2.3 mg kg^−1) than forest site (0.9 mg kg^−1) and grazing site (0.7 mg kg^−1). The overall spatial distribution of extractable P from congregation site to forest site can be described by P = −4.2 x + 45.8; ( R ^2 = 0.97**); the best-fit models for total inorganic N was 0.04 x ^2 − 0.6 x + 3.5; ( R ^2 = 0.89**) and for soil P saturation was −3.6 x + 36.2; ( R ^2 = 0.92**). Results show that the levels of extractable P, total inorganic nitrogen, and soil phosphorus saturation were decreasing from the congregation site to forest site. Although our results may have had supported our hypothesis that congregation site typical on Florida ranchers have greater concentrations of extractable P than in grazing site and forest site, the average extractable P at all three landscape locations did not exceed the crop requirement threshold of 36 mg kg^−1 and the water quality protection threshold of 150 mg kg^−1. Our current pasture management including cattle rotation in terms of grazing days and current fertilizer application had thus no negative environmental impact on landscape with cow–calf Operation.
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spatial distribution of soil carbon in pastures with cow calf Operation effects of slope aspect and slope position
Journal of Soils and Sediments, 2010Co-Authors: Gilbert C. Sigua, S W ColemanAbstract:The rate at which soil carbon (C) accumulates in terrestrial beef agro-ecosystem is uncertain, as are the mechanisms responsible for the current C sink. Broad knowledge of cattle movement in pasture situations is critical to understanding their impact on agro-ecosystems. Movement of free-ranging cattle varies due to spatial arrangement of forage resources within pastures and the proximity of water, mineral feeders, and shades to grazing sites. The effects of slope aspect (SA) and slope position (SP) on nutrient dynamics in pastures are not well understood. Few studies have been made of soil-vegetation and soil-landscape relationships along an elevation gradient in tropical and subtropical regions. Current literature suggests no clear general relationships between grazing management and nutrient cycling. Early study reported no effect of grazing on soils nutrients, while other studies determined increases in soil nutrients due to grazing. We hypothesize that SA and SP could be of relative importance in controlling spatial variability of soil organic carbon (SOC). This study addressed the effects of SA and SP on the spatial distribution of SOC in forage-based pastures with Cow-Calf Operation in subtropical region of southeastern USA. Soil samples were collected at 0–20 and 20–40 cm on contiguous south-, north-, east-, and west-facing slopes across different landscape positions (top slope, middle slope, and bottom slope) of 100 ha pastures during three summer seasons (2004–2006). Soil samples were air-dried, passed through a 2-mm mesh sieve, and visible roots were removed prior to analyses of SOC and other soil properties likely to affect spatial distribution of SOC. Analyses of soils were conducted at the Subtropical Agricultural Research Station in Brooksville, FL, following the dry-ash or the ‘loss-on-ignition’ method. Concentrations of organic carbon in soils from four different SA, three SP, and two soil depths (SD) in 2004, 2005, and 2006 were analyzed statistically following a four-way analysis of variance using the SAS PROC general linear model. There was an SA × SP interaction (p ≤ 0.0001) effect on the concentration of SOC. The two highest concentrations of SOC were observed from top slope (8.4 g kg−1) and middle slope (7.8 g kg−1) in south-facing slope, and the two lowest levels of SOC were in top slope (2.6 g kg−1) and middle slope (3.0 g kg−1) of north-facing slope, respectively. Soil C also varied significantly among SA (p ≤ 0.0001), SP (p ≤ 0.001), and SD (p ≤ 0.0001). Averaged across years and SP, soils on the south-facing slope contained the greatest amount of SOC, while soils on the north-facing slope had the least amount of SOC. Average concentrations of SOC in top slope and middle slope were comparable. These values were significantly (p ≤ 0.05) higher when compared with soils from bottom slope. About 73% of SOC spatial variability could be explained by total clay content. Concentrations of SOC were quadratically (SOC = 0.05 × clay2 − 0.29 × clay + 4.4; p ≤ 0.001) related with total clay content. No other significant correlations between SOC and other soil properties were found. Our results have shown that soils on the south-facing slope had greatest concentration of SOC, while soils on the north-facing slope had the lowest concentration of SOC. The differences may be attributed to topographic aspect-induced microclimatic differences, which are causing differences in the biotic soil component and SOC trend. SA may be acting as an important topographic factor influencing local site microclimate mainly because it determines the amount of solar radiation received. Differences in microclimate are often linked to varying soil moisture and erosion potential and in turn could be used to explain distribution of plant communities. The north-facing slope had the lower forage availability when compared with the south-facing slope. There was a decreasing trend in the average forage availability with decreasing slope. Between the top slope and the bottom slope, forage availability declined from 2,484 to 1,448 kg ha−1, which can be attributed to more grazing activities of cattle at bottom slope. Differences in SOC among different SA and SP could also be explained by varying amount of total clay. Concentrations of SOC were linearly related with increasing total clay content. The greatest amount of SOC was observed from soils located at the top slope of south-facing slope. Of the entire SA, south-facing slope had the greatest concentration of total clay, while the greatest clay content among SP was observed from the top slope. Results further revealed that 73% of SOC spatial variability could be explained by total clay content. The relationship between SOC and total clay content was best described by a quadratic equation: SOC = 0.05 × clay2 − 0.29 × clay + 4.4; R 2 = 0.73; p ≤ 0.001. Results of our study are suggesting that SA and SP could be of relative importance in controlling spatial variability of SOC. Averaged across years, soils on the south-facing slope contained the greatest amount of SOC, while soils on the north-facing slope had the least amount of SOC. Based on the average concentration of SOC, the south-facing slope may have sequestered about 6,460 kg ha−1 of SOC. Results have shown that landscape attributes (e.g., SA and SP) associated with beef cattle pastures as a part of the agro-ecological system could be potential sink for C sequestration, thus reducing atmospheric carbon dioxide concentrations. It is still critical to understand how the interactions of pasture management and landscape are affecting soil C dynamics. More studies are needed to assess the rate at which soil C is accumulating as well as the mechanisms responsible for the current and future C sink in forage-based pastures with Cow-Calf Operations.
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Spatial distribution of soil carbon in pastures with Cow-Calf Operation: effects of slope aspect and slope position
Journal of Soils and Sediments, 2010Co-Authors: Gilbert C. Sigua, S W ColemanAbstract:Background, aim, and scope The rate at which soil carbon (C) accumulates in terrestrial beef agro-ecosystem is uncertain, as are the mechanisms responsible for the current C sink. Broad knowledge of cattle movement in pasture situations is critical to understanding their impact on agro-ecosystems. Movement of free-ranging cattle varies due to spatial arrangement of forage resources within pastures and the proximity of water, mineral feeders, and shades to grazing sites. The effects of slope aspect (SA) and slope position (SP) on nutrient dynamics in pastures are not well understood. Few studies have been made of soil-vegetation and soil-landscape relationships along an elevation gradient in tropical and subtropical regions. Current literature suggests no clear general relationships between grazing management and nutrient cycling. Early study reported no effect of grazing on soils nutrients, while other studies determined increases in soil nutrients due to grazing. We hypothesize that SA and SP could be of relative importance in controlling spatial variability of soil organic carbon (SOC). This study addressed the effects of SA and SP on the spatial distribution of SOC in forage-based pastures with Cow-Calf Operation in subtropical region of southeastern USA. Materials and methods Soil samples were collected at 0–20 and 20–40 cm on contiguous south-, north-, east-, and west-facing slopes across different landscape positions (top slope, middle slope, and bottom slope) of 100 ha pastures during three summer seasons (2004–2006). Soil samples were air-dried, passed through a 2-mm mesh sieve, and visible roots were removed prior to analyses of SOC and other soil properties likely to affect spatial distribution of SOC. Analyses of soils were conducted at the Subtropical Agricultural Research Station in Brooksville, FL, following the dry-ash or the ‘loss-on-ignition’ method. Concentrations of organic carbon in soils from four different SA, three SP, and two soil depths (SD) in 2004, 2005, and 2006 were analyzed statistically following a four-way analysis of variance using the SAS PROC general linear model. Results There was an SA × SP interaction ( p ≤ 0.0001) effect on the concentration of SOC. The two highest concentrations of SOC were observed from top slope (8.4 g kg^−1) and middle slope (7.8 g kg^−1) in south-facing slope, and the two lowest levels of SOC were in top slope (2.6 g kg^−1) and middle slope (3.0 g kg^−1) of north-facing slope, respectively. Soil C also varied significantly among SA ( p ≤ 0.0001), SP ( p ≤ 0.001), and SD ( p ≤ 0.0001). Averaged across years and SP, soils on the south-facing slope contained the greatest amount of SOC, while soils on the north-facing slope had the least amount of SOC. Average concentrations of SOC in top slope and middle slope were comparable. These values were significantly ( p ≤ 0.05) higher when compared with soils from bottom slope. About 73% of SOC spatial variability could be explained by total clay content. Concentrations of SOC were quadratically (SOC = 0.05 × clay^2 − 0.29 × clay + 4.4; p ≤ 0.001) related with total clay content. No other significant correlations between SOC and other soil properties were found. Discussion Our results have shown that soils on the south-facing slope had greatest concentration of SOC, while soils on the north-facing slope had the lowest concentration of SOC. The differences may be attributed to topographic aspect-induced microclimatic differences, which are causing differences in the biotic soil component and SOC trend. SA may be acting as an important topographic factor influencing local site microclimate mainly because it determines the amount of solar radiation received. Differences in microclimate are often linked to varying soil moisture and erosion potential and in turn could be used to explain distribution of plant communities. The north-facing slope had the lower forage availability when compared with the south-facing slope. There was a decreasing trend in the average forage availability with decreasing slope. Between the top slope and the bottom slope, forage availability declined from 2,484 to 1,448 kg ha^−1, which can be attributed to more grazing activities of cattle at bottom slope. Differences in SOC among different SA and SP could also be explained by varying amount of total clay. Concentrations of SOC were linearly related with increasing total clay content. The greatest amount of SOC was observed from soils located at the top slope of south-facing slope. Of the entire SA, south-facing slope had the greatest concentration of total clay, while the greatest clay content among SP was observed from the top slope. Results further revealed that 73% of SOC spatial variability could be explained by total clay content. The relationship between SOC and total clay content was best described by a quadratic equation: SOC = 0.05 × clay^2 − 0.29 × clay + 4.4; R ^2 = 0.73; p ≤ 0.001. Conclusions Results of our study are suggesting that SA and SP could be of relative importance in controlling spatial variability of SOC. Averaged across years, soils on the south-facing slope contained the greatest amount of SOC, while soils on the north-facing slope had the least amount of SOC. Based on the average concentration of SOC, the south-facing slope may have sequestered about 6,460 kg ha^−1 of SOC. Recommendation and perspectives Results have shown that landscape attributes (e.g., SA and SP) associated with beef cattle pastures as a part of the agro-ecological system could be potential sink for C sequestration, thus reducing atmospheric carbon dioxide concentrations. It is still critical to understand how the interactions of pasture management and landscape are affecting soil C dynamics. More studies are needed to assess the rate at which soil C is accumulating as well as the mechanisms responsible for the current and future C sink in forage-based pastures with Cow-Calf Operations.
Terrance M Arthur - One of the best experts on this subject based on the ideXlab platform.
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antimicrobial resistant fecal bacteria from ceftiofur treated and nonantimicrobial treated comingled beef cows at a cow calf Operation
Microbial Drug Resistance, 2016Co-Authors: Getahun E Agga, John W Schmidt, Terrance M ArthurAbstract:We compared the occurrences of 3rd-generation cephalosporin-resistant (3GCr), tetracycline-resistant (TETr), and trimethoprim–sulfamethoxazole-resistant (COTr) Escherichia coli, 3GCr and nalidixic acid-resistant (NALr) Salmonella enterica, and erythromycin-resistant (ERYr) enterococci from the fecal samples of ceftiofur-treated (n = 162) and nonantimicrobial-treated (n = 207) comingled beef cows ≥8 years old, for which complete antimicrobial treatment records were available. The prevalence of 3GCr (17%; n = 369), TETr (88%), COTr E. coli (22%), and ERYr enterococci (69%) was not significantly (p > 0.05) associated with ceftiofur treatment, prior history of other antimicrobial treatments, or duration of time between last antimicrobial treatment and sampling. 3GCr and NALr S. enterica were not detected. The prevalence of tetB was significantly (p < 0.05) higher compared with tetA among TETr E. coli. However, the prevalence of tetA was significantly (p < 0.05) higher than tetB among 3GCr and COTr E. coli. Th...
Ronald Fayer - One of the best experts on this subject based on the ideXlab platform.
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Prevalence of Giardia duodenalis assemblages in weaned cattle on Cow-Calf Operations in the United States.
Veterinary Parasitology, 2011Co-Authors: Mónica Santín, David A. Dargatz, Ronald FayerAbstract:Abstract To determine the prevalence of Giardia duodenalis in weaned beef calves on Cow-Calf Operations in the United States, fecal specimens were collected from 819 calves (6–18 months of age) from 49 Operations. After cleaning and concentration procedures to maximize recovery of cysts from feces, DNA was extracted from each of the 819 specimens. The presence of G. duodenalis was determined by nested PCR of a fragment of the SSU rRNA gene. All positive PCR products were subjected to sequence analysis. The overall sample level prevalence of Giardia was 33.5% with prevalence ranging from 0 to 100% among Operations. The highest within herd prevalence of infected beef calves was found in one Cow-Calf Operation from the South region (100%), followed by a Cow-Calf Operation from the West region (90%), and three Cow-Calf Operations from the Midwest region (87.5, 85, and 85%). Giardia was not detected in samples from 7 Operations including 5 Cow-Calf Operations from the South region, and 1 Cow-Calf Operation each from the Midwest and West regions. Molecular analysis of the Giardia -positive samples identified assemblage E (or E-like) in 31.7% of all samples (260/819) and assemblage A in 1.2% (10/819). A mixed infection with assemblages A and E was observed in four calves from an Operation in Midwest region. The potentially zoonotic assemblage A was detected in specimens from four Operations in Midwest region. These findings indicate that most G. duodenalis found in weaned beef calves was assemblage E which represents no known zoonotic threat. However, the presence of assemblage A in a small number of animals poses a potential risk of infection to humans.
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natural besnoitia besnoiti infections in cattle chronology of disease progression
BMC Veterinary Research, 2015Co-Authors: N S Gollnick, J C Scharr, Gereon Schares, Martin C. LangenmayerAbstract:Bovine besnoitiosis is an emerging protozoan disease in cattle. Neither vaccines nor chemotherapeutic drugs are currently available for prevention and treatment of Besnoitia besnoiti infections. Therefore the implementation of appropriate disease management strategies is of utmost importance. The aim of this longitudinal study was to complement current knowledge on the chronology of disease progression. This was realized by correlating clinical findings in early stages of naturally acquired bovine besnoitiosis with results of real-time PCR of skin biopsies and of two western immunoblots and an immunofluorescent antibody test (IFAT). Animals for this study were obtained by i) closely monitoring a Cow-Calf Operation with a high prevalence of bovine besnoitiosis for cases of acute disease, and by ii) conducting a 12-week cohabitation experiment on pasture with five healthy heifers, a healthy bull and five B. besnoiti infected cows. A control group of six healthy heifers was kept at a minimal distance of 20 m. Further, the spectrum of potential insect vectors was determined. Infected cattle were followed up to a maximum of 221 days after first detection of B. besnoiti antibodies. Two severely affected cows developed visible and palpable alterations of skin, a decrease in body condition despite good feed intake, and chronic bovine besnoitiosis-associated laminitis leading to non-healing sole ulcers. The cows also had high reciprocal IFAT titers and high loads of parasite DNA in skin samples. Two heifers developed a mild clinical course characterized by few parasitic cysts visible in the scleral conjunctivae and vestibula vaginae. Both heifers became infected during the time of high insect activity of the species Musca domestica, Musca autumnalis, Haematobia irritans, and Stomoxys calcitrans. When a third heifer became subclinically infected, low insect activity was recorded. None of the six control heifers contracted a B. besnoiti infection. In chronic besnoitiosis, the severe clinical course apparently corresponded with high reciprocal IFAT titers and high loads of parasite DNA in skin, whereas mild and subclinical cases displayed lower values. Bovine besnoitiosis-associated laminitis represents an important complication in severe chronic disease which severely impairs animal welfare.
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Natural Besnoitia besnoiti infections in cattle: chronology of disease progression
BMC Veterinary Research, 2015Co-Authors: N S Gollnick, J C Scharr, Gereon Schares, Martin C. LangenmayerAbstract:Background Bovine besnoitiosis is an emerging protozoan disease in cattle. Neither vaccines nor chemotherapeutic drugs are currently available for prevention and treatment of Besnoitia besnoiti infections. Therefore the implementation of appropriate disease management strategies is of utmost importance. The aim of this longitudinal study was to complement current knowledge on the chronology of disease progression. This was realized by correlating clinical findings in early stages of naturally acquired bovine besnoitiosis with results of real-time PCR of skin biopsies and of two western immunoblots and an immunofluorescent antibody test (IFAT). Animals for this study were obtained by i) closely monitoring a Cow-Calf Operation with a high prevalence of bovine besnoitiosis for cases of acute disease, and by ii) conducting a 12-week cohabitation experiment on pasture with five healthy heifers, a healthy bull and five B. besnoiti infected cows. A control group of six healthy heifers was kept at a minimal distance of 20 m. Further, the spectrum of potential insect vectors was determined. Results Infected cattle were followed up to a maximum of 221 days after first detection of B. besnoiti antibodies. Two severely affected cows developed visible and palpable alterations of skin, a decrease in body condition despite good feed intake, and chronic bovine besnoitiosis-associated laminitis leading to non-healing sole ulcers. The cows also had high reciprocal IFAT titers and high loads of parasite DNA in skin samples. Two heifers developed a mild clinical course characterized by few parasitic cysts visible in the scleral conjunctivae and vestibula vaginae . Both heifers became infected during the time of high insect activity of the species Musca domestica , Musca autumnalis , Haematobia irritans , and Stomoxys calcitrans . When a third heifer became subclinically infected, low insect activity was recorded. None of the six control heifers contracted a B. besnoiti infection. Conclusions In chronic besnoitiosis, the severe clinical course apparently corresponded with high reciprocal IFAT titers and high loads of parasite DNA in skin, whereas mild and subclinical cases displayed lower values. Bovine besnoitiosis-associated laminitis represents an important complication in severe chronic disease which severely impairs animal welfare.
