Manure-induced soil-water repellency

This laboratory study was conducted to evaluate the potential of nine manure samples from dairy (n = 7), beef (n = 1), and swine (n = 1) to cause water repellency (WR) in six soils; in addition, the duration of WR in two soils was assessed in an incubation study. Manures were applied to supply 40 mg phosphorus (P) kg^-1 to each soil. Sand content in the soils ranged from 179 to 909 g kg^-1. Water repellency was assessed with the water drop penetration time (WDPT) and the degree of repellency with the soil wetted area (SWA) methods. The potential for animal manure to induce WR measured with the WDPT method was dependent on the manure type and soil series. Swine manure did not increase the WDPT of any soil; beef manure increased WDPT in three of the six soils, whereas dairy manure had the greatest effect on WDPT. Results of the SWA method were similar to those with the WDPT; however, there were additional soil-water behavioral patterns identified by the SWA. For example, dairy manure 5 increased WDPT of a soil from 1 to 9 sec, whereas the SWA showed a decrease in the drop area from 120 mm² in the control to 26 mm ² after manure addition. Incubating manure-treated soils for 1 and 2 weeks decreased the induced WR in the Antigo soil, but had little effect on the Rosholt. Field studies should be conducted to assess these phenomena under natural climatic conditions.