4.3. Storm and soil characteristics affecting macropore flow and chemical transport
4.3.1. Methodology
To investigate the effects of storm and soil characteristics on chemical mobility in macropores, undisturbed 30 by 30 by 30 cm blocks of soil were removed from no-till corn fields using the methods outlined in Shipitalo et al. (1990) and Shipitalo and Edwards (1996). The locations of macropores in the base of the blocks were mapped using a grid that corresponded to the dimensions of a 64-cell grid lysimeter used to collect percolate (Fig. 7). In the laboratory, a rainfall simulator was used to apply water at any desired rate and the accumulation of percolate was noted in relationship to the location of macropores on the maps. Results indicated that storm intensity, duration, sequence, and timing, as well as water content of the soil, all affected macropore flow and chemical transport. Rapid movement of water entirely through the 30 cm blocks, at times within 2-4 min of the start of rainfall, was invariably linked to the presence of one or more macropores in the cells that produced percolate.