Effect of Cover and Green Manure Crops on Soil Health, Plant Health and Tuber Yield in Organic Sweet Potato Production

Project Overview

Project Type: Graduate Student
Funds awarded in 2016: $11,956.00
Projected End Date: 10/31/2017
Grant Recipient: University of Missouri
Region: North Central
State: Missouri
Graduate Student:
Faculty Advisor:
Dr. Xi Xiong
University of Missouri


  • Vegetables: sweet potatoes


  • Crop Production: cover crops
  • Education and Training: demonstration, extension, farmer to farmer, on-farm/ranch research
  • Production Systems: general crop production
  • Soil Management: green manures, soil quality/health
  • Sustainable Communities: sustainability measures


    Organic sweet potato growers are challenged by sustainable soil management, which impacts the occurrence of soilborne disease, weed competition, and other pest issues that consequently reduce the tuber yield and/or quality. Being organic, their options are limited for pest control, especially fungal disease that affects the roots and/or tubers. The proposed research aims to develop a strategy of using cover and/or green manure crops, and to evaluate their effects on soil and plant health, as well as disease and weed suppression. The proposed experiment was conducted at a Certified Organic producer’s field based in central Missouri. Effects of rapeseed and cereal rye, both as cover or green manure crop, were assessed in a randomized complete block design for a one-year period. Soil samples were collected for soil organic matter, pH, nutrients, and microbial analysis by using phospholipid fatty acid (PLFA) analysis three times over the course of the study. The PLFA assessed various groups of fungi and bacteria for their diversity and density. Evaluations also included weed coverage, sweet potato plant vigor, disease occurrence (Fusarium root and stem rot), and sweet potato yield. Results from this experiment would increase our knowledge on how to best incorporate cover crops into organic sweet potato production by improving soil health as well as suppressing weed and disease. The expected outcome included development of a strategy for improving sustainability and productivity of organic sweet potato. The project was also evaluated by survey at field days which sampled the farming community for their opinions and acceptance towards this project.

    Project objectives:

    The proposed research would result in an increased knowledge and understanding of:

    • the effect of cover and/or green manure crops on soil properties
    • the effect of cover and/or green manure crops on soil microbial population/activity;
    • The effect of cover and/or green manure crops on sweet potato quality and yield,

    Specifically, the learning outcomes included increased awareness for both farmers and agriculture professionals on the use of cover crops in organic production systems, as well as enhanced skills and motivation to adopt such a practice.

    The action outcomes would include implementation of such a principle and practice in production from farmers who were exposed to and influenced by this project. Agriculture professionals who were involved or aware of this experiment could also be stimulated for performing further research in this area which would consequently facilitate productions of extension publications and field production guides. Additionally, farmers who subsequently benefit from reduced losses and improved economic wellbeing in organic sweet potato production will most likely support research in this nature and consequently enhance the partnership between researchers and stakeholders. This will ultimately result in the sustainable use of resources and hence, improved environmental stewardship and quality.

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.