Scott County Prime Farmland Mapping Project Prepared for the Scott County Planning Department and Jordan Area Visioning Alliance (JAVA) by Greg Schweser, Community Growth Options (U-CGO), University of Minnesota June 2009 1 This project was supported by a grant from the Community Growth Options (U-CGO) program, a joint project of the Center for Urban and Regional Affairs (CURA) and the Hubert H. Humphrey Institute of Public Affairs at the University of Minnesota, with funding from the McKnight Foundation. The content of this report is the responsibility of the authors and is not necessarily endorsed by U-CGO, CURA, the Humphrey Institute, the University of Minnesota, or the McKnight Foundation. Visit U-CGO online at www.cura.umn.edu/cgo.php © 2009 by The Regents of the University of Minnesota. 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Center for Urban and Regional Affairs (CURA) University of Minnesota 330 HHH Center 301—19th Avenue South Minneapolis, Minnesota 55455 Phone: (612) 625-1551 Fax: (612) 626-0273 E-mail: [email protected] Web site: www.cura.umn.edu The University of Minnesota is committed to the policy that all persons shall have equal access to its programs, facilities, and employment without regard to race, color, creed, religion, national origin, sex, age, marital status, disability, public assistance status, veteran status, or sexual orientation 2 Table of Contents Introduction.................................................................................................................................................... 3 Map Descriptions.......................................................................................................................................... 6 NRCS‐Designated Prime Farmland............................................................................................... 6 Crop Productivity Index..................................................................................................................... 7 Land Uses and Land Covers Incompatible with Agriculture............................................ 8 Land Uses and Land Covers Incompatible with Agriculture............................................ 9 Prime Farmland and Incompatible Land Uses and Land Covers................................... 9 Poorly Drained Soils..........................................................................................................................10 Soils Designated as “All Areas Are Prime Farmland” with Incompatible Land Uses and Land Covers....................................................................................................12 Crop Productivity Index and Incompatible Land Uses and Land Covers.................12 Ecological Considerations of Farmland....................................................................................12 Alternative Farming Possibilities................................................................................................13 Alternative Farming Possibilities and Prime Farmland...................................................14 Works Cited...................................................................................................................................................16 Appendix: GIS Mapping Methods Used for the Scott County Prime Farmland Mapping Project...................................................................................................................................18 1 2 Introduction he concept of prime farmland is often a major consideration in conservation efforts T seeking to preserve farmland that lies in the path of urban development. In 2001, the Natural Resources Conservation Service (NRCS) released a National Resources Inventory that documented a loss of about 10 million acres of prime farmland between 1982 and 2001 (NRCS, 2003). As populations grow and cities expand, more farmland will be converted to urban uses, removing land from agricultural production. Although using NRCS designations of land that is “prime farmland” can help to prioritiZe land for protection, other soils that are not considered prime by NRCS standards may be suitable for alternative agricultural systems. As the local foods and sustainable agriculture movements continue to grow and provide an alternative form of agricultural for metropolitan areas, it may be necessary to either expand the concept of prime farmland or use an alternative metric when prioritiZing agricultural land for preservation. There are several categories of NRCS‐designated prime farmland relevant to Scott County. These include parcels where all areas are considered prime, parcels where only drained areas are prime, parcels where only areas protected from flooding or not frequently flooded during the growing season are prime, and parcels where only drained areas that are either protected from flooding or not frequently protected during the growing season are prime. Another category defined by the NRCS is “farmland of statewide importance.” These lands are nearly prime and produce high yields when managed according to acceptable methods (NRCS, 2007). Active management of agricultural land is not taken into account when prime land is determined. Although much land in Scott County is designated “only drained areas are 3 prime,” the degree to which these lands are actually drained and therefore useful as agricultural land is difficult to determine. In addition, designation as prime farmland does not take into account the existing uses or the type of land cover that occupy the land. Areas with scattered development or forests might rest on prime farmland, but it would be unreasonable to assume that such areas would be converted for agricultural production. The prime farmland designation focuses on soil types that provide all of the necessary qualities for the production of food, feed, forage, fiber, and oilseed crops. It is important to understand, however, that soils not identified as prime by the NRCS may still be productive as cropland. The crop productivity index (CPI) is another rating system that ranks crop land on its relative capacity for intensive row crop production. The CPI is a rank of soil types and does not take into account local factors including climate, growing degree days, or precipitation rates, all of which may affect growing conditions. This measurement does assume, however, that lands are adequately managed, not irrigated, artificially drained where required, not frequently flooded on lower lying soils, and not leveled or terraced (Minnesota Land Economics, 2008). When considering alternative farming practices, conventional definitions of prime farmland may not be entirely accurate in predicting the productive quality of some soils. For example, Scott County has large deposits of muck soils spread throughout the county that are not considered prime by the NRCS or highly productive by CPI rankings. However, these soils might be highly suitable for the production of root vegetable crops such as onions, potatoes, or carrots, even though they would require excessive treatments to produce an adequate quantity of row crops such as corn or soybeans (National Cooperative Soil Survey, 2007). Although muck soils might be a nuisance by conventional row‐crop 4 farmers, vegetable growers looking to provide products for local markets might find these lands quite suitable for production. Other sustainable farming methods might use certain lands that are not considered prime farmland to simultaneously produce crops of value and restore ecological systems. For example, farmers may be able to restore eroded slopes by planting perennial grasses for biofuels or managed pasture. 5 Map Descriptions he following set of maps comprises an exploration of Scott County agricultural land. T First, land is analyZed based on the concepts of prime farmland and CPI. These maps are then placed in context of lands that are incompatible with agricultural uses due to existing uses, land covers, and long‐range planning goals. The next set of maps consider ecological factors, as well as the potential for alternative agricultural practices that are sensitive to ecological considerations and the potential for alternative cropping related to various “nonprime” soil features. Finally, traditional and alternative agricultural capacities are combined to demonstrate an alternative perspective on prime farmland that may be suitable for Scott County. NRCS­Designated Prime Farmland This map depicts areas in Scott County that are designated by the NRCS as prime farmland. The NRCS defines prime farmland as land that has the best combination of physical and chemical characteristics for producing food, feed, forage, fiber, and oilseed crops and is also available for these uses. It has the soil quality, growing season, and moisture supply needed to produce economically sustained high yields of crops when treated and managed according to acceptable farming methods, including water management. In general, prime farmlands have an adequate and dependable water supply from precipitation or irrigation, a favorable temperature and growing season, acceptable acidity or alkalinity, acceptable salt and