Covering Ground: Assessing Effectiveness of Interseeding Cover Crops in Late Season Vegetable Crops to Enhance Soil Health in the Northeast

Project Overview

Project Type: Research Only
Funds awarded in 2022: $184,013.00
Projected End Date: 02/28/2025
Grant Recipient: University of Maine Cooperative Extension
Region: Northeast
State: Maine
Project Leader:
Jason Lilley
University of Maine Cooperative Extension

Information Products


  • Vegetables: cabbages, sweet corn


  • Crop Production: continuous cropping, cover crops, intercropping
  • Education and Training: demonstration, extension, farmer to farmer, technical assistance, workshop
  • Soil Management: green manures, soil quality/health

    Proposal abstract:

    This project will investigate best management practices associated with planting cover crops into standing, late season vegetables. Based on our findings, we will educate farmer audiences and promote ecologically, and economically sound practices to improve soil health in crop and vegetable operations in Maine and the Northeast. This three year project will include two years of replicated field trials, along with farmer outreach in years 2 and 3 of the project. 

    Jason Lilley from the University of Maine Cooperative Extension will provide overall leadership for research and outreach aspects of the project. Dr. Rachel Schattman of the University of Maine School of Food and Agriculture will provide leadership on hiring and advising a Master’s level graduate student. She will also be responsible for data analysis. Both Lilley and Schattman will share final results for farmers, ag service providers, and academic audiences. A grower advisory committee will provide project input and guidance based on past experiences with cover crop species selection, timing of seeding, and planting methods in various vegetable crops. The input of the advisory committee will also be used to ensure that research findings are applied to real-world contexts in a way that is meaningful for the farming community. 

    Results from a survey about cover cropping practices on Maine farms (n= 27), showed that 77.8% of respondents (n=21) are limited in their ability to plant cover crops due to “late season cash crops coming out too late”. 74.1% of respondents (n= 20) stated that research- based data about interseeding in the Northeast would help them with decision making about late season cover cropping. 

    We hypothesize that 1) Interseeding at an appropriate growth stage of sweet corn and fall cabbage will result in high cover crop biomass and with no negative effects to the crops;  2) incorporation of cover crop seed into the soil at interseeding will result in the best cover crop germination, biomass, and weed control; and 3) that utilizing lower biomass cover crops such as annual ryegrass and crimson clover will minimize nutrient and water competition. 

    Findings from this research will be shared at four regional grower meetings/ conferences including the Northeast Regional Cover Crop Conference, the Maine Fruit and Vegetable School, the Vermont Vegetable and Berry Association Annual Conference, and the Maine Organic Farmers and Gardeners Association’s Farmer to Farmer conference. Project outcomes will include a graduate thesis, one or more peer-reviewed publications, and Extension publications. Anticipated benefits include that farmers will be able to identify equipment and strategies for interseeding that will fit their existing production systems. This will result in the total vegetable acreage planted to overwintered cover crops being significantly increased by the use of interseeding.

    Project objectives from proposal:

    This project will develop recommendations for interseeding cover crops into late season vegetables in the Northeast to improve overwintered soil coverage. The goals of the proposed research are to investigate key management considerations including: timing of planting the cover crop in relation to the cash crop, methods of seeding, and how these factors affect crop nutrient availability, pests, and yields. We will also investigate cover crop species performance. By sharing these research results with conventional and organic vegetable farmers, we will support farmers with the information they need to protect more acres overwinter with cover crops.

    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.