The Use of Regression Models to Predict Spatial Patterns of Cattle Behavior

Hubbard

et al. 2009

Nutr Cycl Agroecosyst

Despite substantial measurements using both laboratory and field techniques, little is known about the spatial and temporal variability of nitrogen (N) dynamics across the landscapes, especially in agricultural landscapes with cow-calf operations. This study was conducted to assess the comparative levels of total inorganic nitrogen, TIN (NO 3 -N ? NH 4 -N) among soils, forage, surface water and shallow groundwater (SGW) in bahiagrass (Paspalum notatum, Flueggé) pastures. Soil samples were collected at 0-20, 20-40, 40-60, and 60-100 cm across the pasture's landscape (top slope, TS; middle slope, MS; and bottom slope, BS) in the spring and fall of 2004 , 2005and 2006 , respectively. Bi-weekly (2004-2006 groundwater and surface water samples were taken from wells located at TS, MS, and BS and from the run-off/seepage area (SA). Concentrations of NH 4 -N, NO 3 -N, and TIN in SGW did not vary with landscape position (LP). However, concentrations of NH 4 -N, NO 3 -N, and TIN in water samples collected from the seep area were significantly (P B 0.05) higher when compared to their average concentrations in water samples collected from the different LP. Average concentrations of NO 3 -N (0.4-0.9 mg l -1 ) among the different LP were well below the maximum, of 10 mg l -1 , set for drinking water. The maximum NO 3 -N concentrations (averaged across LP) in SGW for 2004, 2005 and 2006 were also below the drinking water standards for NO 3 -N. Concentration of TIN in soils varied significantly (P B 0.05) with LP and soil depth. Top slope and surface soil (0-20 cm) had the greatest concentrations of TIN. The greatest forage availability of 2,963 ± 798 kg ha -1 and the highest N uptake of 56 ± 12 kg N ha -1 were observed from the TS in 2005. Both forage availability and N uptake of bahiagrass at the BS were consistently the lowest when averaged across LP and years. These results can be attributed to the grazing activities as animals tend to graze more at the BS. The average low soil test value of TN (across LP and soil depth) in our soils of 10.9 mg kg -1 (5.5 kg N ha -1 ) would indicate that current pasture management including cattle rotation in terms of grazing days and current fertilizer application (inorganic ? feces ? urine) for bahiagrass pastures may not have negative impact on the environment.

Section: Discussionsupporting

confidence: 90%

Nitrogen in soils, plants, surface water and shallow groundwater in a bahiagrass pasture of Southern Florida, USA

Hubbard

et al. 2009

Nutr Cycl Agroecosyst

“…On average, we did not find the concentrations of total phosphorus in surface water to be distinctly different (p ≥ 0.05) from the amount of total phosphorus in shallow groundwater, although the concentration of total phosphorus in top slope wells was significantly greater than that of water samples from the middle slope wells, bottom slope wells, and from the seepage area. Non-uniform grazing distribution by livestock on landscapes can be caused by many variables such as water location (Holechek 1988;Ganskopp 2001), minerals (Martin and Ward 1973), herbage mass (Senft et al 1983), and ruggedness (slope) of the terrain, which exist at a variety of scales (Smith 1988). In our pastures, slope position was confounded with mineral, water source, and to some degree shade, which were located near the top slope and bottom slope positions.…”

Section: Discussionmentioning

confidence: 99%

Quantifying phosphorus levels in soils, plants, surface water, and shallow groundwater associated with bahiagrass-based pastures

Hubbard

2009

Environ Sci Pollut Res

Research on the pathways and rates of movement of phosphorus deposited in urine and dung through various pools and back to the plants will be the focal point of our future investigations. Further studies are needed to determine whether the environmental and ecological implications of grazing and haying in forage-based pastures are satisfied over the longer term. New knowledge based on the whole-farm approach is desirable to identify pastureland at risk of degradation and to prescribe treatments or management practices needed to protect the natural resources while maintaining an economically and environmentally viable operation.

“…When livestock tend to graze some pastured areas more than others like in our study (bottom slope [ middle slope [ top slope), plant communities can degrade and soil physical and chemical attributes can change with time. Nonuniform grazing distribution by livestock on landscapes can be caused by many variables such as water location (Holechek 1988;Ganskopp 2001), minerals (Martin and Ward 1973), herbage mass (Senft et al 1983), and ruggedness (slope) of the terrain, which exist at a variety of scales (Smith 1988). In our pastures, slope position was confounded with mineral, water source, and to some degree shade, which were located near the top slope and bottom slope positions.…”

Section: Effects Of Slope Positionmentioning

confidence: 99%

Spatial distribution of soil phosphorus and herbage mass in beef cattle pastures: effects of slope aspect and slope position

Albano

et al. 2010

Nutr Cycl Agroecosyst

Characterizing and assessing spatial distribution of soil phosphorus and herbage mass in relation to landscape properties, land use, or landscape positions is important for understanding how pasture sustainability can be managed and improved properly. Our reason for conducting this study was to determine the effects of different slope aspects and slope positions on spatial distribution of soil phosphorus and herbage mass in subtropical pastures. Soil and forage samples were collected from contiguous south-, north-, east-, and west-facing slopes across different landscape positions (top slope, middle slope, and bottom slope) in 100 ha of bahiagrass (Paspalum notatum)-based pastures from 2003 to 2006 in subtropical region of southeastern USA. Averaged across years, soils on the north-facing slope contained the greatest amount of soil phosphorus (12.4 ± 2.7 mg kg -1 ) when compared with other slope aspects. Slope aspect may be acting as an important topographic factor influencing local site microclimate mainly because it determines the amount of solar radiation received. The greatest herbage mass (averaged across year) of 2,967 ± 980 kg ha -1 and the highest phosphorus accumulation of 7.7 ± 3.0 kg ha -1 for bahiagrass were from the top slope position. There was a significant (P B 0.05) decrease in the average herbage mass and phosphorus accumulation with decreasing slope (top to middle slope). Between the top slope and the bottom slope, herbage mass declined from 2,967 ± 980 to 1,805 ± 370 kg ha -1 while phosphorus accumulation was reduced by approximately 40% (7.7-4.6 kg ha -1 ). Results of our study may increase awareness on how the arrangement of food, water, and shelter and their interactions with topographic and landscape features can significantly influence the movement of animals and utilization of different pastures' resources. While our study supports our hypothesis that slope aspect and slope position could be of relative importance in controlling spatial distribution of soil phosphorus and herbage mass, broad knowledge of cattle movement in pasture situations is as critical to understanding their impact on agroecosystems.