Rotationally grazing hogs for orchard floor management in organic apple orchards

The effectiveness of hogs in controlling weed competition and removing drop apples from organic orchards was evaluated. Two densities of hogs (46.45 m(2)/pig and 24.4 m2/pig) were pastured in an organic apple orchard for 2 days during June (bloom) and October (post-harvest), 2005, to determine their effectiveness in removing orchard floor vegetation and drop apples as compared to an un-mowed control plot. The impact on vegetation was assessed by comparing vegetation sample weights from the control plot with each treatment plot immediately following both grazing periods and in August. To determine the risks associated with grazing hogs in the orchard, leaves, fruit, soil and manure were analyzed for total coliforms and Escherichia coli immediately following the spring grazing period and again in October, following harvest. For all vegetation assessments, a significant difference occurred between the control (June = 1231.73 kg/ha; August = 2058.02 kg/ha; October = 2083.89 kg/ha) and treatment plots (46.45 m2/pig treatment: June = 584.75 kg/ha; August = 1215.26 kg/ha; October = 1633.34 kg/ha and 24.40 m2/pig treatment: June = 443.09 kg/ha; August = 1502.41 kg/ha; October = 741.63 kg/ha). However, inconsistencies were observed between the two hog densities and grazing periods, with significant differences occurring between the treatments during the fall period (P < 0.001), but not during the bloom period (P = 0.368) or at mid-season (P = 0.143). Differences were also seen between high and low traffic areas, but there was no interaction between the traffic areas and the two hog densities. Escherichia coli was not detected in any samples from the control plot or on leaves or apples in either of the treatment plots. Pre-harvest, the control plot leaf samples had higher total coliform counts than leaves taken from either treatment plot. The control plot apple samples had fewer total coliforms than the low swine density (46.45 m2/pig) plots, but more than the high swine density (24.4 m2/pig) plots. Soil E. coli and total coliform numbers in the treatment plots increased over the season compared with the control. The hogs left less than 4% of drop apples compared to the control plot, with a 0.07 kg/ha difference between the low and high pig densities.