Manure and Soil Health: Understanding and Advancing the State of the Science

Manure and Soil Health: Understanding and Advancing the State of the Science


Farmers and ranchers are becoming increasingly aware of the importance of soil quality/health to the productivity and sustainability of their agricultural system. Research and field observations have demonstrated that carefully managed manure applications can contribute to improved soil quality with limited environmental and social risks. However, a comprehensive assemblage of outputs and conclusions from research studies, field trials, soil labs databases, and other sources has never been developed as a basis for identifying knowledge gaps and directing future activities. Therefore, the purpose of the proposed initiative, Manure & Soil Health: Understanding and Advancing the State of the Science, is to assemble current knowledge on this topic, make it available to those influencing manure and land management decisions, and use it to plan and facilitate future research and programming activities.


This planning project is designed to facilitate: 1) assembly of data to summarize the current state of knowledge on the role of manure in soil health improvement; 2) distribution of this knowledge to those influencing manure management decisions; and 3) identification of future programming needs related to soil health management and funding opportunities to support such programming. The goals of the project will be achieved through four endeavors: 1) distribution of mini-grants (4-5) to support a comprehensive review of literature on the relationship between manure utilization and soil health by undergraduate or graduate students; 2) web-based roundtable discussions among manure and soil health management professionals; 3) a blog focused on manure and soil health; and 4) a face-to-face meeting of the working group to identify research needs to fill gaps in the current knowledge of the role of manure in soil health, subject-related programming needs, and relevant external funding opportunities that can support these long-term efforts.

Significant existing science based literature and data bases could provide a foundation for our understanding of manure’s impact on soil health. Examples include:

  • Scientific literature focused on land application of manure on water quality including that used to establish and verify phosphorus index tools. Such literature often reports changes in soil organic matter, total runoff volume (indicator of soil infiltration rate and bulk density), soil pH (impacting soil nutrient availability), and other soil metrics that may provide indicators of soil health.
  • Private and public sector soil test data bases used commonly for fertility recommendations provide substantial source of data on soil organic matter, pH, and nutrient availability. By sorting these databases based upon indicators of history of manure application such as high vs. low soil phosphorus levels, these soil test databases may reveal several common indicators of soil health based upon high manure vs. low or no manure application history.
  • Multi-decade university field studies of impacts of manure application to cropland are available. For example, University of Nebraska-Lincoln has maintained a comparison of manure vs fertilizer application plots since 1942 with the plots split in 1953 to evaluate 4 manure application rates. In 1928, plans were developed for establishing 10 soil conservation experiment stations and later expanded to include 35 sites (Wischmeier, 1955). Research programs were initiated at each of these locations to investigate effective methods for controlling soil and water losses including use of manure at several site. This data may have value for our examination of manure’s impact on indicators of soil health.

Alignment with Regional Priorities. This proposed effort aligns with the goals of The Network to increase connectivity and learning among professionals and partners focused on water-related issues, utilizes existing soil health-related research outputs among cooperating universities to build capacity among all partners, and addresses nutrient and manure management, soil health, and land use and development practices through improving our understanding of multiple manure and soil management practices that positively impact soil health and productivity.

The Mississippi River/Gulf of Mexico Hypoxia Task Force outlined in their 2008 Action Plan several key actions designed to promote best management practices and conservation practices for nutrient management at the local and regional level and maximize results of these efforts by continuously assessing the state of the science and engaging relevant stakeholders. This project will address several action items related to advancing science and improving awareness by supporting our effort to identify existing scientific uncertainties related to the role of manure in soil health improvement, promote effective communication about existing strategies, anddetermine appropriate actions to address scientific uncertainties through targeted research efforts while improving knowledge of soil health and the role of manure in soil health improvement. By assembling the current state of knowledge on manure and soil health, previous applied research projects can be leveraged to assist stakeholder with decision-making. The manure and soil health blog will improve stakeholder awareness of land and water issues related to manure and non-manure management practices. This planning project will also increase soil conservation efforts within the Basin by targeting research relating manure management with soil health.

The Association of Public and Land-grant Universities (APLU) identifies six priority areas in Natural Resources Road Map (2014). This project will help achieve goals identified in the following priority areas: 1) sustainability, 2) water, 3) agriculture and 4) education. The literature review component of this project will provide a comprehensive overview of the existing knowledge of the link between manure and soil health.

Intended Impacts

Several key components of this project will facilitate the creation of programming activities related to manure and soil health. These activities will: 1) increase connectivity and learning between university professionals and partners across a diversity of water-related disciplines and roles and 2) generate measurable economic, environmental, and social impacts in the short and long-term, with a focus on nutrient and manure management and soil health. Connectivity and learning between university professionals and partners across a diversity of water-related disciplines and roles will be increased by bringing together experts to evaluate the current state of knowledge and identify critical issues in manure management related to soil health. This knowledge will then guide decision makers about how manure management can be leveraged to increase soil health within a watershed.


Rick Koelsch
Livestock Environmental Engineer, University of Nebraska-Lincoln