Influence of soil amendment and crop species on nutrient cycling in a St. Paul urban garden

An experiment was conducted from 2017-2021 at the University of St. Thomas research garden (Saint Paul, MN) to determine rates of nutrient recycling and loss from compost applied to urban gardens. Thirty-two 4 square-meter study plots received one of six different soil amendment treatments, with four different crops growing on each plot. Meteorological data includes hourly measurements of rainfall, solar radiation, temperature and relative humidity, and wind speed and direction, from June 2017-August 2021. Hourly soil moisture measurements were recorded at depths of 10 cm, 20 cm, and 30 cm, from June-December 2021. Annual crop harvest totals from each subplot are reported for 2017-2021. Leachate was collected from lysimeters installed in each of the 132 subplots weekly from June-October of each year (2017-2021), recording total volume. Leachate subsamples were analyzed for NO 3 -N, NH 4 -N, and PO 4 -P. Soil samples were collected at the beginning and end of the growing season in 2017, and every two weeks during the growing season from 2018-2021, and analyzed for pH, organic matter, Bray-1 extractable P, available K, nitrate, and ammonium, at the University of Minnesota Analytical Research Laboratory.