PROBLEMS IN PREDICTING TRANSPORT OF CRYPTOSPORIDIUM FROM GRAZINGLANDS IN THE SOUTHERN PIEDMONT OF THE US

Authors: Fisher, Dwight; Endale, Dinku; Steiner, Jean; YOUNG, M - GEORGIA TECH; PENNELL, K - GEORGIA TECH; AMIRTHARAJAH, A - GEORGIA TECH

Submitted to: EPA Workshop on the Overland Migration of Cryptosporidium
Publication Type: Proceedings
Publication Acceptance Date: 9/21/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary: The Southern Piedmont extends along the eastern face of the Appalachian Mountains from Virginia to Alabama. The land has made rapid growth in manufacturing, service, transportation, and tourism. Agricultural soil erosion was severe but has stabilized at a relatively low level since 1970. The sediment still present in streambeds may affect the movement of the microscopic pathogen called cryptosporidium. Accurate estimates of infiltration rates are needed to predict the movement of cryptosporidium. Soils also vary greatly in the rate at which rainfall is absorbed by the soil. Management can greatly change this infiltration rate but only a history of management or a direct management of the amount of organic matter in the soil can be used to predict the infiltration rate. Urbanization is reducing infiltration and increasing runoff that may also impact movement of microbes. Calves are typicaly born in the early spring and they are particularly susceptible to infection by cryptosporidium. They become infectious during this time and this may result in a predictable annual cycle of high levels of cyrptosporidium in the spring. Farm ponds reduce bacterial numbers and may reduce other microbes and provide a viable conservation tool. Cattle could be placed above a pond prior to or during significant rainfall to reduce the change of pathogen movement off the farm.

Technical Abstract: The Southern Piedmont extends along the eastern face of the Appalachian Mountains from Virginia to Alabama. The Piedmont was historically agricultural but has made rapid growth in manufacturing, service, transportation, and tourism. Soil erosion in the Piedmont continued at a high level from 1860 to 1920 and then declined until 1970 when it reached a abaseline. The sediments still present in the streambeds may interact with the cryptosporidium oocytes and complicate modeling the movement of oocytes. Soil carbon is also highly variable, accumulates slowly, and can be reduced rapidly by conventional tillage practices. Estimates of overland transport of cryptosporidium must account for variation in infiltration rates resulting from variable soil carbon. Urbanization is reducing infiltration and increasing runoff. This may impact agricultural land due to increased peak flows in surface waters flowing from urban areas. In cow-calf production systems the calves are typically born in th early spring. This may result in a predictable annual cycle of cryptosporidium oocyte loading as the young stock become infected, shed oocytes, and then develop immunity. Farm ponds reduce bacterial levels and may also reduce levels of cryptosporidium. Farm ponds are common in beef production systems. Animal position within the landscape relative to the pond could have an impact on transport of cryptosporidium. This may be especially relevant just prior to or during significant rainfall events that produce runoff.