Joint 56th Annual North-Central/ 71st Annual Southeastern Section Meeting - 2022

Paper No. 9-21
Presentation Time: 8:00 AM-12:00 PM


LARSON, Mary1, KAIRIES-BEATTY, Candace1, BENSON, Sydney1 and FRANZ, Jeanne2, (1)Winona State University Department of Geoscience, PO Box 5838, Winona, MN 55987-0838, (2)Winona State University Department of Chemistry, Winona, MN 55987

The Sustainable, Edible, Education, Discovery (SEED) Garden, a vegetable garden owned by Winona State University (WSU) and maintained by students, is intended to give students access to locally grown foods and to educate on sustainable gardening methods. Soil was brought in from an outside, unknown source and all plants are grown within six raised garden beds. During the 2020 and 2021 growing seasons, several areas of the garden exhibited issues with poor (or no) plant growth. Poor plant growth can result from limited nutrient availability or nutrient deficiency, pH outside of the range of optimal growth, or because of the physical properties of the soil itself (texture, compacted soil, etc.). The goal of this research was to identify reasons for a lack of growth in the garden and to provide recommendations for soil amendments for future years. Soil samples were collected in November 2020. Soil pH was evaluated using standard methods for soil pH. Color was determined using a Munsell Soil Color book and texture was evaluated following the USDA soil texture chart. To evaluate percent organic matter, a loss on ignition procedure was conducted following Konen et al., 2002. Splits of samples were sent to Minnesota Valley Testing Laboratories for analysis of cation exchange capacity (CEC) and plant available nitrogen, potassium, phosphorus, magnesium, calcium, sulfur, iron, manganese, zinc, copper, and boron. Sample pH ranged from 7.31-7.98, all falling within an optimal pH range (6.00-8.00) for plant growth. Organic matter content ranged from 1.74-22.06%; with 2 samples below the 3.1% optimal threshold. CEC was between 20.8-40.4 meq/100g. Phosphorus was between 28-350 ppm, with 12 samples below the optimal concentration of 200 ppm. Nitrogen concentrations ranged from 32-259 ppm; most crops planted prefer nitrogen levels >100 ppm. One major issue in the garden was poor water retention caused by shallow garden beds, rocky soil, and low organic matter content. The soil did not have the proper water holding capacity to maintain healthy plant growth. Based on the results of this work, recommended amendments to increase nitrogen, phosphorus, and organic matter content and methods to increase the soil’s water retention included the addition of compost to the soil, a redesign of the garden beds and the removal of the gravel from the soil beds