Abstract: Healthy soil is vital for ecosystem health. Soil provides plants with structural support, water, nutrients, and microbial relationships needed for creating the amount of biomass critical for trophic interactions and carbon capture. Conventional agriculture practices degrade soil health; however, even small plots of natives within agricultural settings provide disproportionally large benefits to both ecological and agricultural landscapes, meaning even small plots of native plants can greatly impact large-scale soil health. Small plots of mixed native plant species improve soil health but offer little in the way of income opportunities for producers. Native monoculture plots, however, may offer producers an opportunity to harvest and sell seeds, taking advantage of the increasing demands of the native seed market while also increasing soil health. Therefore, the goal of this study is to quantify the effects of small plots of native monocultures on soil health indicators and compare them to the soil from conventional crop plots. We investigated biological indicators of soil health such as organic matter fractions, organic carbon, and microbial communities as well as abiotic soil health indicators such as nutrient composition. We hypothesize that, compared to crop plots, native monoculture plots will have higher microbial diversity and higher amounts of soil nutrients. To test our hypothesis, we compared soil health characteristics from plots containing five established native monocultures: Dalea candida, Agastache nepetoides, Glycyrrhiza lepidota, Liatris ligulistylis, and Tradescantia occidentalis; and one crop plot planted with a corn and soybean rotation. During the second season of growth, monthly soil samples were taken from each plot and soil indicator values were compared using Tukey’s HSD post hoc tests after performing an analysis of variance (ANOVA).
Results suggest that native plant species influenced soil health differently than crop rotations after two seasons of growth. Compared to crop plots, soil samples from two species of native plants, Agastache nepetoides and Tradescantia occidentalis, had higher fungi-to-bacteria ratios (p = 0.0160 and p < 0.0001, respectively), and higher amounts of saprophyte biomass (p = 0.0040 and p = 0.0484, respectively). Soils from the Agastache nepetoides plots also had higher amounts of Pre18 cyclo fatty acids (p = 0.0022) and potassium (p = 0.0159). These two species of native plants show potential for improving soil health after two years of establishment and adding these two native monocultures to marginal, conventional croplands may add soil health benefits during early establishment periods while providing a marketable crop for producers.
