A state-of-the-art review is presented concerning the transport of nutrients (N and P), oxygen demanding compounds (BOD and COD), indicator organisms and pathogens in runoff from land areas receiving animal wastes. Three different land areas are considered: pastures and rangelands, land application sites, and feedlots. For land application sites, results of a linear regression analysis indicated highly significant correlations between constituent (N or P) loading rate and its concentration in runoff water, and also between constituent loading rate and its mass yield rate. Field plots receiving manure during winter and spring, and subject to snowmelt runoff followed a different relationship compared to those receiving applications during summer and fall, and not subject to snowmelt runoff. Effects of various factors, such as time and method of application, soil and cropping management practices, in relation to transport of nutrients are discussed. The limitations of the available data are discussed in terms of identifying future research needs. The greatest need appears to be that of relating the limited data on small plots to larger watersheds, and edge-of-field losses to receiving waters.
Journal articles from the Grassland Society of Southern Africa (GSSA) African Journal of Range and Forage Science as well as related articles and reports from throughout the southern African region.