- Fruits: berries (cranberries)
- Crop Production: nutrient cycling
- Education and Training: focus group, workshop
- Pest Management: field monitoring/scouting
- Soil Management: nutrient mineralization, organic matter, soil analysis
Cranberry (Vaccinium macrocarpon), a low-growing, woody, evergreen vine, is a native species in Wisconsin. Cranberry is a unique crop because its roots can form an association with ericoid mycorrhizal fungi. Currently ammonium is considered the main source of nitrogen, and ammonium-based fertilizers are applied at an annual rate of 20 – 60 lb N/acre in Wisconsin. Further research on the cranberry-ericoid mycorrhizal fungi relationship will provide growers with important information that may help them to exploit a naturally existing association that enables cranberries to access organic forms of nitrogen. The objectives of this study are to document the spatial variability of nitrogen pools and fluxes and determine the extent to which ammonium, nitrate, and dissolved organic nitrogen are utilized as nutrient sources for cranberries in both peat and sand based beds. The results may contribute to increasing cranberry production sustainability by improving growers’ nutrient management strategies through a reduction of fertilizer inputs. This is especially important as ammonium-based fertilizers account for about 5% of overall production costs and surface water runoff from cranberry beds may carry nitrogen inputs to adjacent rivers, lakes, and reservoirs. Participating growers will provide information on bed history and activity. They will receive data and results periodically throughout the project. Information from this study will be disseminated to a larger grower audience through the annual Wisconsin Cranberry School and submissions to the UW-Extension Bulletin.
Project objectives from proposal:
The short-term outcome from this agroecosystem study will provide a characterization of the spatial and temporal variability of nitrogen in both peat and sand based cranberry beds. This study will also provide information on the relationship between ericoid mycorrhizal fungi and their ability to access dissolved organic forms of nitrogen in the field. The intermediate-term outcome is to discuss results with growers and review current nitrogen management plans. Over the long-term, a better understanding of the patterns of nitrogen use by cranberries will increase production profitability and sustainability. Knowledge of the fluctuation in nitrogen availability within a bed and the differences between sand and peat based beds may increase yield. Additionally, if plants are able to use ericoid mycorrhizal fungi to obtain organic nitrogen, then growers may find it more efficient to encourage fungal colonization rather than applying inorganic nitrogen fertilizers.