THE RELATIONSHIP OF WISCONSIN SOIL AND HONEYCRISP APPLES

Wisconsin agriculture is an integral part of the Midwestern economy. Although cranberries and cherries serve as the state’s most exported fruit, a lesser known but popular local crop is apples. Terroir, the study of environmental factors on plant growth and the fruits borne by those plants, is often applied to wine grape studies, but has recently branched out to other agricultural fields. Terroir relates acutely to Wisconsin’s apple growing agriculture in that the state’s varying bedrock geology interacts with the growth and products of the apple trees. This research will focus on the soil and bedrock aspect of Honeycrisp Apple terroir. By collecting soil, leaf and apple samples, we anticipate linking elements in the soil to the products produced by the applicable trees.

We visited six apple orchards around the state of Wisconsin, exploring three different bedrock types. All trees from which samples were taken produce Honeycrisp apples, are grown on a M7 rootstock and are over 10 years old. Two soil pits were dug at each site from which samples of the A-Horizon and the B-Horizon were taken. Additionally, leaf samples were taken from sample trees. Predominant minerals for the A and B-Horizons will be identified to help characterize soil type. Grain size was measured to place each soil on a ternary soil plot and to predict how well the soil can hold or expel water. X-ray Diffraction (XRD) and X-ray Fluorescence (XRF) analyses are being applied to determine the mineralogical and geochemical composition of the soils. In addition, biological samples have been sent to A&L Canada Laboratories Inc. for analysis. Preliminary soil analysis shows clay-rich soils for a majority of the locations. As data is gathered in the next couple months, we anticipate producing a roadmap of the elements as they start in the soil, travel through the tree and reach their destination in the leaves and the apple.