Manure Spreading and its Effects on Soil Compaction and Corn Yield in Southern Wisconsin.
Gregg Sanford1, Joshua Posner1, Janet Hedtcke1, Ron Schuler2, and Jon Baldock3. (1) Agronomy Dept., Univ. of WI, 1575 Linden Drive, Madison, WI 53706, (2) Biological Systems Engineering Dept., Univ. of WI, 550 Babcock Drive, Madison, WI 53706, (3) AGSTAT, 6394 Grandview Rd, Verona, WI 53593
Potential compaction from manure spreading equipment is one factor that limits the land grain farmers are willing to make available for applying livestock waste. To study compaction caused by manure spreaders, eight sites were set up in the fall of 2004 and six in 2005. At each site three treatments were compared (manure, farmer’s check w/o manure, and loaded tanker traffic only), and replicated three times. Typical axel weights of the full slurry tankers were 9 to 14 Mg (10 – 15.5 tons). All trials were planted to corn during the 2005 and 2006 growing seasons. Hand held penetrometer readings, taken at the V3 corn stage (approximately seven months after slurry application) showed no increased compaction due to tanker traffic. Results from the 2005 season also showed no significant difference between treatments across the eight environments with a mean corn yield of 11.85 Mg ha-1 (189 bu/a). At an additional site, the impact of multiple passes of heavy slurry equipment was examined. This experiment was set up as an augmented 2 ´ 2 factorial with two levels of traffic (1 or 6 passes with a loaded tanker), two nitrogen sources (manure and commercial fertilizer), and a check. In this case manure was spring applied and penetrometer readings were able to clearly identify the wheel traffic two months after application with in-track yield reductions of 10-15%. Whole plot yields for the 2005 season, however, did not significantly differ between any of the five treatments, with an overall mean of 12.17 Mg ha-1 (194 bu/a). In the first year of field trials, which was drier than normal during manure application, compaction from manure spreaders did not adversely affect corn yields.