Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 8, 2003
Publication Date: July 1, 2004
Citation: Kleinman, P.J., Sharpley, A.N., Veith, T.L., Maguire, R.0., Vadas, P.A. 2004. Evaluation of phosphorus transport in surface runoff from packed soil boxes. Journal of Environmental Quality. 33:1413-1423. Interpretive Summary: Packed soil runoff boxes have contributed substantially to our understanding of P transport in the environment. Research with soil boxes provides the quantitative underpinnings for some aspects of the P Index, a tool currently used by over 42 states to aid farmers in field-based nutrient management decisions. In this study, packed soil boxes were critically evaluated to determine how they relate to other methods of study and whether inherent properties of soil boxes bias research on soil and manure management. Results of this study show that, despite many differences between runoff boxes and field plots, some critical conclusions derived from these two methods of study (e.g., the relationship of soil P to P in runoff) are similar. In addition, because results of manure management experiments are primarily controlled by high concentrations of soluble P in applied manures, soil box dimensions do not have a significant effect on runoff P losses.
Technical Abstract: Phosphorus in runoff from manure-amended soils has been implicated in accelerated eutrophication. The development of P-based nutrient management strategies to protect water quality has relied, in part, on research using simulated rainfall and either field plots or surface runoff boxes packed with soil to study the effects of soil P and manure management on P in runoff. Experiments were conducted to evaluate P transport processes using field plots (1-m wide and 2-m long) and surface runoff boxes (0.2-m wide and 1-m long), under simulated rainfall (7.5 cm h-1 for 30 min of runoff). Field plots had greater infiltration and lower runoff volumes than runoff boxes, whereas erosion and total P (TP) concentrations were significantly greater from runoff boxes than from field plots. However, the relationship between Mehlich-3 soil P and dissolved reactive P (DRP) concentration in runoff was similar for field plots and runoff boxes as well as for the acidic and alkaline soils examined in the study. When runoff properties from boxes of differing depths, either 5-cm or 25-cm, were compared before and after dairy, poultry, and swine manures were broadcast at 100 kg TP ha-1, few runoff, erosion, and TP differences were noted. Prior to manure application, erosion and consequently runoff TP concentration, differed significantly between box depths, although DRP concentrations and hydrology were similar. Following manure application, runoff DRP increased as a function of water extractable P concentration in applied manure, with few significant differences in erosion, DRP or TP between 5- and 25-cm deep runoff boxes. Translocation of manure P into the soil, possibly a key process controlling P availability to runoff, was generally not significant below 1 cm depth. This study highlights differences in hydrology, erosion, and particulate P transport between field plots and runoff boxes. However, trends in runoff DRP concentration generally remained consistent across field plots and runoff boxes of various dimensions due to buffering by soil or high concentrations of soluble P in recent manure additions.