Cover Crops for Sustainable Pest Management and Soil Quality in Production Nurseries

2011 Annual Report for LNE08-274

Project Type: Research and Education
Funds awarded in 2008: $175,920.00
Projected End Date: 12/31/2011
Region: Northeast
State: Maryland
Project Leader:
Dr. Paula Shrewsbury
University of Maryland

Cover Crops for Sustainable Pest Management and Soil Quality in Production Nurseries


In 2011 research related to soil quality continued. This included final soil samples to evaluate the cumulative effect of two plus years of cover crop use in tree bare zones and open fields in nurseries. Interaction with grower participants (on-farm visits and email) led to further study to determine impacts of additional management practices on soil quality and to elucidate more sustainable nursery practices in two of the three cooperating nurseries. This study evaluated the rotation of grass allies and tree rows between new field plantings. Data that were collected from the various studies from 2008 – 2011 were processed and analyzed to assist in identifying effective cover crop species and management practices that lead to more sustainable production of woody trees and shrubs. Project PD’s presented talks at stakeholder conferences on sustainable practices and their use in production nurseries.

Objectives/Performance Targets

Of the 150 MD growers trained at field days and other events, a minimum of 25 that have never used cover crops in their nursery will use cover crops in at least one production field, and five nurseries will adopt one new ecologically based pest or soil management practice to reduce pest pressure or improve soil quality.


In the 4th year (2011, 3rd full year) of the proposed project milestones 4, 5, 6, and 7 were addressed. The PD’s implemented a change in the original proposal in that we decided to conduct an additional field study to address the benefits of rotating grass allies and tree rows at time of field replant (continuation of milestone 4). Two nursery growers worked with PD’s implementing this research in 2011. PD’s and project beneficiary members are in the process of evaluating research results to identify sustainable practices in nurseries (milestone 5). Data continue to be analyzed. A field demonstration on cover crops with an associated presentation by PD’s in collaboration with the Maryland Nursery and Landscape Summer Field Day trained ~ 75 green industry professionals and extension personnel on cover crops (milestone 7, performance target 8).

Impacts and Contributions/Outcomes

Research from fall 2008 and two full years (2009, 2010), including sampling into 2011 has been completed and data were (and continue to be) processed and analyzed. At this time preliminary results have been summarized for the cover crop selection and establishment, and the soil quality and pest management components of the project. Including preliminary analysis of the two additional field research components incorporated into the project in 2010 and 2011.

Cover crop treatments for both the spring/summer and fall plantings overall did not consistently establish as well as hoped. This was the case in the open field, tree row zone, and fallow row studies. Although data on establishment is still being evaluated, preliminary observations suggest that forage radish, crimson clover, cowpea, and Austrian winter pea have promise. Arthropod specimen identification has begun to determine arthropod composition and abundance in the different cover crop species. Data from the predation study in tree rows with and without cover crops have been analyzed. Data from the grass alley studies has been through a first stage of analysis to compare 3 grass mixes with and without cover crops for their benefits.

To determine the cumulative effect of two plus years of management using cover crops on soil quality analysis in 2011 included falling head saturated infiltration rate using a single ring. Surface aggregates were collected in the field, air dried, and tested for stability by slaking. Lab analyses included a measurement of labile carbon by permanganate oxidation, and seven-day nitrogen mineralization under controlled incubation conditions.

A further soil quality comparison was initiated in May 2011 between two divergent zones common in Maryland nurseries and managed consistently for five years: the bare or weedy zones within tree rows, and the grassed alleyways between tree rows. The relative soil quality in these areas could predict which zone is more suitable for replanting, and turf is known to quickly build soil organic matter, a cornerstone of soil health. This comparison is for evaluating the occasional farmer practice of rotating new plantings into the strips that had been in grass in the previous rotation to compare soil quality in the two management zones. Soil quality indicators tested in the two treatment zones were earthworm counts, dry understory plant mass, root mass per volume soil, single ring falling head saturated infiltration rate, penetration resistance, aggregate stability by slaking, depth to A horizon, total C and N, permanganate oxidizable carbon, seven-day N mineralization, three-day CO2 evolution, and microbial biomass carbon. These measurements will be compared and a recommendation made as to the potential benefit of rotating tree plantings into grassed aisles.

Soil removal resulting from excavation of balled and burlaped trees was further evaluated in November 2011 to assess the accuracy of approximating soil removal by measuring hole volume and soil bulk density.

Project PD’s presented on sustainable practices at multiple conferences. Approximately 75 green industry stakeholders were informed on the use of cover crops and sustainable practices via presentations and a demonstration field planting of the more successful cover crops from this study. There was a high level of interest in the cover crops by nursery growers and green industry professionals (landscapers, crop consultants).


Raymond Weil
University of Maryland
Department of Environmental Science and Technology
1109 H.J. Patterson Hall
College Park, MD 20742
Office Phone: 3014051314
Stanton Gill
University of Maryland
11975-A Homewood Road
Ellicott City, MD 21042
Office Phone: 3015969413
Charles Schuster
University of Maryland
Montgomery County Extension
18410 Muncaster Road
Derwood, MD 20855
Office Phone: 3015902807