EVALUATION OF SOIL HEALTH IN THE INDIGENOUS LEARNING GARDEN AT WINONA STATE UNIVERSITY

Winona State University’s (WSU) Indigenous Learning Garden (ILG) is a space for all to acknowledge and respect the culture, traditions, and history of Indigenous peoples. During its construction soil was brought from an outside source and a variety of native Minnesota plant species were installed. During 2020 plants in multiple garden beds failed to establish, potentially because of poor soil quality due to limited nutrient availability or deficiency, sub-optimal pH, poor soil texture or a combination of these factors. The purpose of this research was to evaluate soil health in the ILG and to make soil amendment recommendations as needed. Soil samples up to about a 10-inch depth were collected using trowels. In addition, two cores down to about 25 inches from one of the beds were collected using a soil auger. Color was evaluated using a Munsell soil color book and texture was evaluated following the USDA texture protocol. Percent organic matter was determined using a loss-on-ignition technique. Soil pH was evaluated following standard laboratory protocol. Splits of samples were sent to Minnesota Valley Testing Laboratories, Inc. for analysis of plant nutrient availability, including potassium, nitrate nitrogen, phosphorus, magnesium, sulfur, calcium, manganese, boron, copper, zinc, and iron. Texture was inconsistent across the samples and varied from sandy clay, sandy loam, to clay loams. Soil color was black to reddish black. All samples were within optimal pH range (6.2-7.3) and organic matter fell within or exceeded the recommended range of 3.1-4.5%. Primary nutrients (potassium, nitrate nitrogen, phosphorus) exhibited the greatest deficiencies, with all beds deficient in potassium (< 161 ppm) and nitrogen (< 25.5 ppm), while phosphorus was deficient (< 26 ppm) in most of the beds. Calcium and magnesium were present in excess amounts for all samples (> 2500 ppm and >150 ppm, respectively), while all samples were sulfur deficient (< 7 ppm). Micronutrients were in excess in all beds. It is recommended that a chemical fertilizer or natural amendments such as compost or composted manure be added to the beds to increase concentrations of nitrogen, phosphorous and potassium in the soil. Additional amendments, including coffee grounds, bone char, and kelp meal can add nitrogen, phosphorous, and potassium respectively.