Soil Health and Cropping Systems

Dr. Ashley Keiser and others labeling Miscanthus giganteus (Freedom) with 13C-enriched CO2.
Nutrient Management

Title:  How does soil health differ between perennial and annual cropping systems across contrasting nitrogen fertilization treatments?

Location:  Boone and Newell

Time Period:  2017-2020

Research Team:  Ashley Keiser, Emily Heaton, Andy VanLoocke, and Marshall D. McDaniel

Project Description:  Building soil health increases agroecosystem resilience, but soil health is controlled by complex interactions between land management, climate, existing site fertility, and plant-soil feedbacks. While soil health can be assessed by many indicators from soil carbon (C) and nitrogen (N) content to crop yield, soil organic matter (SOM) content is the metric with extensive control over a wide range of ecosystem properties. For example, increased SOM content indicates greater soil C stocks, increased nutrient availability to plants, and, consequently, greater positive feedbacks between plants and soil. Many factors contribute to maintaining or building SOM, including fertilization (e.g., nitrogen retention) and crop type (e.g., perennial versus annual). When an annual cropping system is switched to perennials with greater root systems, such as grassland, soil carbon stocks increase. There is then potential for a concomitant increase in SOM, thereby shifting towards an increasingly resilient ecosystem. This has direct implications for sustainable agriculture because internal C and N cycling and retention, and thus soil health, may be improved through plant-soil C exchanges. Our research examines plant-soil feedbacks on soil C, and thus soil health, by determining the allocation of plant-derived C to plant, soil and microbial pools across cropping systems, N fertilization inputs, and site fertility. Our results will be used to: inform stakeholders through multiple outlets and extant programming; and improve agroecosystem models used by the scientific community to understand ecosystem function.

Specifically, we ask:

  1. How is C allocated in perennial versus annual plants and their associated belowground networks, and does this differ by site?
  2. How does soil microbial biomass and function, the engineers of soil health, differ between soils and crop type?
  3. Do additional N inputs (fertilizer application) affect C allocation both within the plant (above- versus belowground) and in the soil (microbial biomass and SOM)?


Funders:  Leopold Center for Sustainable Agriculture - Iowa Nutrient Research Center

Disclaimer:  This is an active research site, please contact the research team prior to planning any site visits.