Submitted to: Transactions of the ASAE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/1/1995
Publication Date: N/A
Interpretive Summary: Scientists often use small plots to simulate what is happening in large agricultural fields. Rather than treating a ten acre field with manure and measuring runoff, we often treat a ten foot wide area and measure runoff. This has led to the criticism that the results would not be the same if we had treated a bigger area. Therefore, the objective of this study was to determine what effect (if any) there is from the area treated with manure on concentrations of nitrogen, phosphorus and carbon in runoff water. Small plot studies were conducted with rainfall simulators. The results indicated that there was no effect of manure-treated length.
Technical Abstract: Using experimental data and/or mathematical simulation models to identify practices that reduce pollution from manure-treated areas is sometimes perceived as limited by the unknown validity of extrapolating plot-scale data to larger areas and by uncertainties in modeling transport of various pollutants. The objectives of this study were to assess the effect of length of manure treatment on runoff concentrations of poultry litter constituents and to define the modes of transport (particulate versus soluble) for N, P, C, and solids. Poultry litter was applied to three fescue plots (1.5 * 18.3m) equipped with runoff collection gutters at 3 m intervals along the lengths of the plots. Runoff was generated using rainfall simulators (50 mm hr**-1 for 1 hour after runoff). Samples were analyzed for TKN, organic N (Org-N), NH3, NO3, TP, TOC and TSS. Manure-tre length had no effect on runoff concentrations of any parameter, indicating that a manure treated length of only 3 m would have been sufficient to simulate runoff quality associated with longer manure length treatments.