| Studies have shown that the hydrology of a pasture system is influenced by its vegetative characteristics. It was the objective of this study to evaluate the effect of five forage species at varying canopy heights (one day v six weeks growth post harvest) on surface runoff volume and infiltration volume, as well as surface runoff quality from plots fertilized with poultry litter. The five forage species were: “Alamo” switchgrass (Panicum virgatum L.), Caucasian bluestem (Bothriochloa caucasia (Trin.) C. E. Hubb.), ‘Greenfield’ bermudagrass ( Cynodon dactylon (L.) Pers.), ‘Pete’ eastern gamagrass (Tripsacum dactyloides (L.) L.), and ‘Kentucky-31’ tall fescue (Festuca arundinacea Schreb.). Poultry litter was surface applied annually at 9 Mg ha−1. Rainfall simulations were used to produce runoff events during spring, summer, and fall to examine seasonal variations. Although there were no statistical differences in runoff volumes among cut canopy and full canopy covers, runoff volumes were reduced by full canopies, for all seasons, for all species except bermudagrass. Comparisons of runoff volumes between species showed that tall fescue had significantly lower runoff volumes for three of the four runoff events. There were no differences in runoff volumes among the other four species, for any runoff event. Infiltration volumes were larger in tall fescue plots for all runoff events, compared to the other four species. Neutron probe data supported these results, with tall fescue plots consistently having the lowest volumetric water content to a depth of 35 cm. Differences in total N, P, and metal concentrations in the runoff between the species were small, therefore the significantly lower total N and P loadings from the tall fescue plots were due to differences in runoff volumes. Although tall fescue was not the largest biomass producer, its higher N and P concentrations resulted in removing the greatest amount of N and P from the system in over the course of the trial. Tall fescue was more effective than the other grass species at increasing infiltration, and reducing runoff volumes, thereby reducing edge of field loss. |
