Applied Engineering in Agriculture , 25 , 2009

Pandey, V., Kiker,. G.A., Campbell, K.L., Williams, M.J., Coleman, S.W.

A study was conducted to quantify the amount of time spent by grazing cattle near or in water locations (wetlands, ditches, and water troughs) across seasons in a cow‐calf production ranch in south Florida. Prolonged hot summers in these regions can cause physiological heat stress in cattle and drive them into water‐filled ditches and wetlands in order to cool down. Because of the numerous ranches in the region, it is perceived that this activity is contributing towards the phosphorus loading into the receiving water body, Lake Okeechobee. Cattle position data was monitored continuously using GPS collars. Data was recorded every 15 min during a 5‐day period in spring (March), summer (June), fall (late August), and winter (November or December) from 2001 to 2003. The average percentage of daily time spent by cattle near/in water locations (water trough, wetland, and ditch) during the warm season (summer + fall) was 11.45 ± 0.39% and 6.09 ± 0.69% during the cool season (winter + spring). Overall, the cattle utilized water‐filled features somewhat more during warm seasons, with some exceptions under higher temperatures found in southern Florida winters. Temporal, sub‐daily analysis of the use of water troughs revealed very little usage during early morning and night and increased use as the day progressed. Similar analysis of wetlands use showed greater utilization during late morning and nights in the cool season. Utilization of ditches was fairly consistent throughout all years; more during warm seasons and less during cool. Current hydrological modeling systems that are actively used to represent the nutrient‐enriched agricultural enterprises in south Florida lack the ability to comprehensively represent the dynamics of the animal‐plant‐soil system. This study will provide crucial information for model developers who may utilize these results to develop more detailed hydrological and nutrient loading models.