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

Final 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
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Project Information

Summary:

This 3.5 year project included two primary objectives. First we conducted research in field production nurseries where the major goal was to demonstrate the effects of cover crop use on pest management, soil quality and plant health. We consulted heavily with nursery producers to identify issues that served as barriers for the adoption of cover crops in nurseries. We identified four major areas of nurseries where cover crop use could be feasible, identified cover crop species that performed relatively well in the nursery, and information growers would need to know to implement cover crop practices. The best performing cover crops in the bare zone and fallow row studies include: forage radish (Raphanus sativus), crimson clover (Trifolium incarnatum ‘Dixie’), buckwheat (Fagopyrum esculentum), Austrian winter pea (Pisum arvense), and cowpea (bigna unguiculata ‘Iron and Clay’. In the open field studies, forage radish was the best but sunn hemp (Croralaria juncea ‘Tropic Sun’) and sudex (Sudan x Sorgham hybrid) also did well. We also conducted research that related to the issue of soil loss during ball and burlap harvesting, specifically a best practice for estimating lost. The magnitude of root weight compared to soil weight in the root ball was trivial.

Second, we conducted educational programs that focused on cover crop use that included field demonstrations, and information on other sustainable practices. We educated ~ 400 individuals on these topics at four field day demonstrations, in addition to a few hundred through presentations at state and regional conferences.

A final post survey was given to attendees of all of the field days in March 2012. Of the ~220 attendees to the three field days, 129 were sent and asked to complete the post survey, and 21 (16%) of those responded. Unfortunately the response rate was low. This was a three part survey: Part 1targeted practitioners such as growers or landscapes (13 responses); Part 2 targeted extension educators, consultants (three responses); and Part 3 was a catch all – other (likely government personnel) (five responses). The objective of the survey was to evaluate changes in use of cover crops (new user, expanded area) and other sustainable practices. Other factors evaluated include changes in knowledge and potential benefits gained (ex. reduced pesticide or fertilizer). The final objective of this survey was to verify that the project reached its performance target.

Unfortunately the response to this post survey was so low (only 13 practitioners responded) there is no way to estimate if 25 practitioners who have never used cover crops, are now using them. The survey does indicate that people are / will be adopting new sustainable practices in their nurseries, and more than one practice. This suggests the project has reached part of its performance target of “five nurseries adopting one new sustainable pest or soil management practice”. Several of these practices were evaluated in our project such as: cover crops in various nursery areas (8), filling holes following ball and burlap harvest (3), top dressing (3), and rotating new tree/shrub planting into previous grass alleys (6). When those implementing some type of sustainability practice were asked if they see an increase in benefits, responses ranked from highest (combined response of somewhat and a lot, vs not at all) to lowest were: reduced soil erosion (92%); improved soil quality (85%); improved plant health (77%); economic benefit (77%); reduced need for fertilizer (69%); increased natural enemy activity (60%); and reduced need for herbicides, insecticides and miticides (55%).

Other types of people that responded to this survey include Extension Educators and other trainers (3). In this group knowledge was increased (66%) following a field day, and 100% plan on training on the use of sustainable practices and cover crops. Others included government, park, and retail garden center personnel (5). 80% felt they were more knowledgeable on sustainable practices following a field day, and 40% felt the training would benefit them in their job.

Introduction:

The use of cover crops and other sustainable practices has become increasingly popular in traditional agriculture. However, even with the wide selection of cover crops available, their known benefits, and the ongoing efforts of SARE, Cooperative Extension, NRCS, and others to promote their adoption, the use of cover crops and sustainable practices in general, by nursery growers has been limited. In a survey of NE region nursery professionals, 48% said they would adopt sustainable practices if they had more knowledge on “how to”, and 33% needed evidence of feasibility of practices in nurseries (Ashley 1991). When asked what support they needed answers were written materials, workshops, and consultation. We conducted a Pre-proposal Survey (2007) of MD nursery growers that found similar results – less than 18% had tried cover crops. During phone interviews, when growers were asked what they need to know for them to use cover crops, the consensus was: 1) What cover crops species to use, and 2) How to plant and manage the cover crops in terms of planting methods, formation, and timing. Clearly, there is a need and desire by growers to be informed and have demonstrated in nurseries which cover crop species to use and methods to integrate them, and other sustainable practices into nurseries.

Therefore, the target of this project was to increase the adoption of cover crop and other sustainable practices in nurseries. Through on-farm research we evaluated effects of cover crop species and methods of implementation in field production woody plant nurseries on pest (insect and weed) suppression, soil quality, and plant health. In addition, grower education focused on the results of the on-farm studies and training on other ecologically-based pest, soil and plant management practices.

Selection of cover crop species and methods of their integration into nursery systems examined in this on-farm research and demonstration were based on extensive discussions with our nursery growers / beneficiaries, our Pre-proposal Survey, empirical data from agricultural systems, and the experience of project investigators and collaborators. A typical tree and shrub field production nursery differs from traditional annual agricultural systems. Woody plants are perennial crops (3 -12 years in field), grown in rows from 200 to 500’, between every two to five rows of plants are “grass alleys” (usually tall fescue) to drive equipment on and to reduce soil erosion, and weed free or “bare zones” of soil ranging from 2 – 5’ in width are maintained (via herbicide) adjacent to the rows of plants. Plants within a field are harvested over time (3-5 yrs) leaving fallow areas within the rows. Trees and shrubs are grown as pot-in-pot, in root bags, or they are ball and burlap at harvest. At times equipment activity on the fields is high. Plants are usually on drip irrigation. Under these conventional practices, growers are challenged by numerous problems. These include among others, soil compaction and erosion, reduced organic matter content; a unique complex of pests; high inputs of pesticides and nutrients and thereby risk of pollution of watersheds; and reduced biodiversity of arthropod and soil fauna resulting in more frequent pest problems.

Nursery growers need to implement sustainable production practices to address these and other problems. Production of nursery crops differs from other agricultural systems resulting in unique concerns by growers. Concerns include: competition of cover crops with the perennial nursery crop for moisture and nutrients slowing down “time to sale”; equipment needs and methods of planting, maintaining and killing cover crops have to be adapted to the unique layout (bare zones, alleyways, rows of plants) of nurseries vs annual crops; and nurseries frequently combat a complex of pests not common to annual crops. In addition, the aesthetic appearance of the nursery is an important marketing tool for many growers because buyers and landscape architects come to the nursery to select trees and shrubs. Research-based information is needed addressing these concerns.

The strongest justification for this project was: if nursery growers are going to adopt cover crop practices, we need to provide growers with cover crop information specific to nursery production and demonstrate their use and benefits, including cost effectiveness and feasibility, in field production nurseries. The research and demonstration component of this proposal combined with the educational component targets to accomplish this. Furthermore, we predict that once nursery growers see the benefits of cover crops in nurseries, they will be stimulated to try other sustainable practices. As such, this project addressed important issues relating to pest suppression and improved soil quality, in addition to other issues such as soil loss during the harvest of ball and burlap plants.

Therefore, the target of this project was to increase the adoption of cover crop and other sustainable practices in nurseries. We proposed through on-farm research to evaluate effects of cover crop species and methods of implementation in field production woody plant nurseries on pest (insect and weed) suppression, soil quality, and plant health. In addition grower education will focus on the results of the on-farm studies and training on other ecologically-based pest and soil management practices.

Performance Target:

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.

Three hundred and ninety growers, extension and government agency personnel, and consultants attended four on-farm field days, two of these were held at project cooperator nurseries, the 3rd and 4th were held in conjunction with the MD Nursery and Landscape Association Annual Summer Field Days (2010 and 2011). All field days provided demonstration of cover crops and their use. Surveys were conducted at the end of two of the field days, and a survey regarding adoption of sustainable practices and changes in knowledge was conducted in March 2012.

Unfortunately the response to this post survey was so low (only 13 practitioners responded) there is mathematically no way to estimate if 25 practitioners who have never used cover crops, are now using them. The survey does indicate that people are / will be adopting new sustainable practices in their nurseries, and more than one practice. This suggests the project has reached part of its performance target of “five nurseries adopting one new sustainable pest or soil management practice”. Several of these practices were evaluated in our project such as: cover crops in various nursery areas (8), filling holes following ball and burlap harvest (3), top dressing (3), and rotating new tree/shrub planting into previous grass alleys (6). When those implementing some type of sustainability practice were asked if they see an increase in benefits, responses ranked from highest (combined response of somewhat and a lot, vs not at all) to lowest were: reduced soil erosion (92%); improved soil quality (85%); improved plant health (77%); economic benefit (77%); reduced need for fertilizer (69%); increased natural enemy activity (60%); and reduced need for herbicides, insecticides and miticides (55%).

Cooperators

Click linked name(s) to expand
  • Stanton Gill
  • Charles Schuster
  • Raymond Weil

Research

Materials and methods:

This 3.5 year project consisted of three major components: 1) on-farm research to demonstrate cover crop species and benefits to pest management and soil quality in field production (tree and shrub) nurseries, 2) outreach in the form of field days at nurseries, presentations at local and regional re-certification and nursery association conferences, and printed / web-based publications to extend information to beneficiaries (nursery growers, consultants, and extension personnel), and 3) impact assessment to verify changes in: practice (integration of cover crops), knowledge (informed on what cover crops to use, their benefits, and how to integrate them), interest in sustainable practices; and assess value of the research based information to nursery growers using surveys, visits to nurseries, phone calls, and records kept by nursery collaborators. Methods for each of these major components are described below.

Research and Demonstration:

Cover crop studies were conducted at three MD field production nurseries from fall 2008 through spring 2011. Treatments were implemented in fields of established plants. Cover crops were evaluated in four types of areas common to most field nurseries: 1) bare zones, 2) fallow areas, 3) open fields, and 4) grass alleyways. Bare zone and fallow area studies were conducted at all 3 nurseries, whereas open field and grass alley studies were conducted at one nursery. Treatments were cover crops species (varied species and time of planting based on cover crop cultural requirements). Comparisons were made of the same crop plant (tree species) under conventional practices (control). Therefore, cover crop treatments were planted in the fall and spring / summer of each year of the study (ex. fall 2008, spring 2009, fall 2009, spring 2010, and fall 2010; final soil evaluations were taken in spring 2011). Sampling was conducted to measure treatment effects on: 1) pest suppression via measurement of pest activity, natural enemy abundance and diversity; 2) soil quality via measurements on active organic carbon, N mineralization rate, soil organic matter content, water infiltration rate, soil aggregate stability, compaction, and pH; and 3) plant health via growth measurements (internodal growth, caliper size). In addition, cover crops were evaluated for establishment (cover crop and weed coverage and biomass), herbivory by arthropods, damage by mammals (deer, rodents), aesthetics, and phenology.

Two additional soil studies were implemented in 2010 and 2011. One evaluated soil loss estimation from ball and burlap harvesting (conducted at two nurseries). The second evaluated the potential benefits of rotating grass alleys and previous tree rows at the time new fields are replanted. The prediction is that grass alleys would have higher quality soils than previously used tree rows.

Cover crop – Bare zones. Weed free or “bare zones” of soil ranging from 4 – 5’ in width are maintained (herbicides) adjacent to trees in the rows. The experimental design was a randomized complete block design (RCB) with three nurseries (blocks) where each nursery had two replicates of two different tree species (blocks) (four replicates / nursery) = 12 replicates total. There were four treatments per replicate. Cover crops evaluated included Forage radish, Raphanus sativus (Brassica), Crimson clover, Trifolium incarnatum L., alyssum, and buckwheat. Crops were planted in the “bare zone” while still maintaining a 1’ circle of bare soil around tree trunks. Forage radish is a winter or spring annual. Its known benefits include root penetration to alleviate soil compaction, weed suppression, and organic matter for soil improvement. It alters N cycling by taking up N in the fall (likely reducing N leaching) and releases it in the spring (when trees and shrubs need N). Forage radish has, to date, not been evaluated for its benefits to pest insect suppression. Crimson clover is a winter annual legume cover crop (seeded in fall and blooms in spring). Its known benefits include a source of slow-release N when it dies in summer, makes soil P available, suppresses weeds, and is attractive to natural enemies. Alyssum is a cool season low growing (~6”) annual flowering plant. Buckwheat is a warm season, tall (~2’) annual flowering plant. Alyssum and buckwheat have been shown in other studies to be attractive to natural enemies. Treatments included: 1) fall seeded forage radish and spring seeded alyssum; fall seeded crimson clover and spring seeded buckwheat; fall seeded forage radish and spring seeded forage radish; and no cover crop (conventional control).

Cover crop – Fallow areas. Plants within a field are harvested over time (3-5y rs) leaving fallow areas within the rows that are maintained as bare (herbicides) or become weedy. The experimental design was a RCB design with three blocks (nursery) and two replicates at each nursery (= six replicates total). There were eight treatments consisting of various combinations of cover crop species and time of seeding (spring or fall) and conventional control. Cover crop treatments included: 1) conventional control; 2) fall forage radish, spring buckwheat/sunflower mix; 3) fall forage radish / buckwheat mix, spring cowpea; 4) fall crimson clover, spring forage radish / coriander mix; 5) fall Austrian winter pea (spring blooms), spring forage radish / cowpea mix; 6) fall and spring New Zealand white clover / strawberry clover mix; 7) fall and spring forage radish / ‘Good Bug Blend’ mix; and 8) fall and spring hard fescue mix.

Cover crop – Open fields. Open fields exist in nurseries as fields yet to be planted into a tree crop or fields that are fallow for a period of time between tree harvest and replant of new trees. This provides an optimal time to implement cover crops. This study took place at one nursery and was set up as RCB design with four blocks (location within the nursery) and 3 treatments per block. Treatments included: 1) conventional control; 2) fall forage radish and spring Sudex; and 3) fall forage radish and spring Sunn hemp.

Cover crop – Grass alleys. Grass alleys are planted between every 2-5 rows of trees or shrubs to drive equipment on and to reduce soil erosion. These alleys are typically planted with tall fescue and are labor intensive in that they need to be mowed. This study was conducted at one nursery using a split plot design where the plot level treatment was grass species [(three grass treatments = tall fescue mix; fine fescue mix (chewings, hard, and red); No mow lawn mix (Prairie Nursery, mix of hard and red fescues)] and the treatments split between each grass plot treatment was cover crop (three treatments = white clover; birds foot trefoil; no cover crop). This design resulted in 9 treatment combinations. A legume winter perennial cover crop, white Dutch clover (Trifolium repens), will be over-seeded into grass alleys. Benefits include: reduced soil erosion, added source of N from legume cover crops, increase biodiversity and floral resources that should attract beneficial arthropods. Fine fescues and No mow mix should require fewer mowings per season than tall fescue. Benefits should be reduced costs of labor, fuel inputs, and mechanical wear and tear on mowers.

Soil loss from ball and burlap harvesting. The most common method of harvesting field grown trees and shrubs is to use a mechanical spade to dig the tree, and then ball and burlap the root ball for shipping. The issue with this method is that soil is being removed from the field which indicates this is a not a sustainable practice, especially over the long term. The objective of this study conducted in 2010 was to determine the amount (mass and volume) of soil removed during ball and burlap tree and shrub harvest. It was hypothesized that the amount of soil removed with ball and burlap tree and shrub harvest is largely predictable from tree spade geometry (volume of hole) and soil bulk density with little effect of tree root mass. To test this hypothesis the study was conducted at a nursery in Montgomery County MD that used two tree spade types (conical and hemispherical) for ball and burlap harvesting for two tree species (Norway maple and Emerald green arborvitae). A treeless ball was also dug with each spade (control). Hole volume and soil bulk density core measurements were recorded. Roots were washed, removed, and weighed (fresh and dry weight).

Comparison of soil quality between grass alleys and tree rows for tree replant. Field grown trees and shrubs are grown in rows with grass alleys between every two to four rows. Historically, farmers usually replant young trees into the same tree rows that have recently been harvested. In that case, they usually incorporate or top dress with organic matter. Some innovative farmers are trying a new approach of replanting into previous grassed alleys, with the idea that the grasses build soil quality. Therefore, the objective of this study conducted in 2011 was to evaluate and compare identified soil quality properties between grass alleys and tree rows under 5 years of management to identify the optimal zone to plant a new tree crop. The study was conducted at two of our cooperating nurseries. A RCB design was implemented with two nurseries (blocks) each with two blocks, and two treatment levels (bare and grass zones) (= eight replicates). Several physical, chemical, and biological properties were measured that serve as indicators of the soils ability to perform functions that support ecosystem services.

Outreach / educational activities:

Four field days were conducted as part of this project. Two took place at a collaborating nursery (2008 Raemelton Farm; 2009 Snell Nursery) and the two were conducted (summer 2010 and 2011) in conjunction with the Maryland Nursery and Landscape Association Annual Summer Field Day. Three of these field days demonstrated cover crops. Throughout this project, PD’s presented sustainable topics at state and regional conferences that targeted green industry professionals and extension and government personnel.

Impact assessment:

A written survey was given to field day participants at the conclusion of the 2008 and 2009 Field Days to assess their current production practices and their use of cover crops, and the effectiveness of the training in increasing their knowledge on and the likelihood they would implement sustainable practices. A final survey was given to attendees of the field days in March 2012 to evaluate their adoption of cover crop and other sustainable practices. Discussions were ongoing throughout the project (via phone, nursery visits, field days) with nursery cooperators and beneficiaries relating to the potential costs and benefits of the project.

Research results and discussion:

Milestones (from original proposal):
1. Four nursery growers commit to conduct the research / demonstration on their nurseries and be part of the Project Beneficiary Committee (PBC). Two other growers commit to be members of the PBC. Committee meets to finalize research protocol.
2. Three growers conduct and implement the research / demonstration protocols on their nurseries for year one.
3. The PBC examines results from first year of project and provide feedback and modify, if necessary the 2nd year research protocol.
4. Three growers conduct and implement the research and demonstration protocols on their nurseries for year two.
5. PBC identifies cover crop species and implementation strategies that reduce pest pressure, improve soil quality, and are feasible to implement in nurseries.
6. Each of the 3 demonstration nurseries will host a field day for ~75 growers and extension personnel.
7. 300 growers in the NE region will attend training on the species, benefits, and methods of implementation demonstrated in this project; additional cover crops and their management, pest suppression, soil quality, and broader benefits; and previously demonstrated (SARE funded) ecologically-based pest and soil management practices.

Milestones 1, 2, and 6:
In the first year (2008) of the proposed project the project leaders net worked with nursery growers through phone discussions and nursery visits to discuss the project and obtain input on the research protocol. Three MD nursery growers (nursery collaborators) committed to conduct the research / demonstration on their nurseries and be part of the Project Beneficiary Committee (PBC). Nurseries were Raemelton Farm, Ruppert Nursery, and Snell Nursery. In addition, one other MD grower committed to be a member of the PBC. The project leaders and PBC further developed and finalized the research / demonstration protocol, and to identify field plots to be used for research at each of the nurseries. In the fall (2008) project leaders and nursery collaborators set-up and implemented the cover crop studies (research / demonstration) at the cooperating nurseries for the bare zone, fallow row, and open field studies. Sampling was conducted and data were collected in each of the nursery study areas (except grass alleys) and for each cover crop treatment to determine: 1) arthropod abundance and taxa; 2) coverage / establishment of cover crop treatments relative to weeds and bare ground; 3) arthropods in on trees (bare zone study only); 4) cover crop and weed biomass; 4) soil quality characteristics, and 5) plant growth (caliber, shoot length).

In fall 2008, Raemelton Farm hosted a nursery field day entitled ”Staying Profitable Through Sustainable Field Nursery Production Practices”. Approximately 70 growers, consultants, and extension and government personnel attended. A survey was presented to the attendees at the end of the day to assess the change in knowledge and usefulness of the sustainability topics presented. See below for results.

Milestones 3, 4, 6, and 7:
In the 2nd year (2009, 1st full field season) project leaders interacted with the PBC via phone discussions, emails, and nursery visits to discuss the first field season and obtain feedback. Research in the fall of 2008 went relatively well with good cover crop establishment in the bare zone and open field studies. Cover crop treatments in the fallow row study varied in their establishment. Only minor changes were made. In winter 2009 Raemelton Farm planted new grass alleys with the appropriate species and design as described in the protocol. As grass established sampling and data collection included: 1) number of mowings per year; 2) arthropod abundance and taxa; and 3) establishment / coverage of grass and cover crop treatments. Results on mowing indicated that the use of the fine fescue mix or No mow mix compared to a tall fescue mix resulted in a reduction of four mow cycles in years 1 and 2 post –seeding (more frequent mowing helps to suppress weeds), and a reduction of eight mow cycles in the following years. Based on this data, time to mow, hourly wage, and a 7 year production cycle we estimate a savings of $115 / acre / production cycle or $6,912 / 7 year production cycle for the 60 acres in production at Raemelton Farm.

The three nursery collaborators worked with project leaders implementing the proposed research in the 2009 field season. Spring cover crop treatments were planted and monitored as above; and fall cover crop treatments were planted and monitored. In late summer 2009 sampling was also conduct on plant damage. As the season progressed there was a lot of variation in establishment, and poor establishment in some cases, within cover crop treatments. Weed management / competition was a major issue. The project participants further developed the research / demonstration protocol as issues arose during the field season, and based on discussions with the nursery collaborators, tried to improve cover crop establishment. Preliminary analysis of the data was initiated but challenging do to the variation in establishment of cover crops within treatments. Because of variation in cover crop establishment the project leaders decided to conduct an additional 3rd (2010) field season of research than was originally planned in the project proposal.

In the fall (2009) a nursery field day was conducted at one of the cooperating nurseries (Snell Nursery) demonstrating the proposed project and other sustainable practice relevant to nursery production. The field day was entitled “Sustainable Nursery Practices that Improve your Profitability”. A survey was presented to the attendees at the end of the day to assess the change in knowledge and usefulness of the sustainability topics presented. See below for results. Presentations on sustainable practices also were given at green industry conferences reaching MD and regional stakeholders.

Milestones 3, 4, 5, and 7:
The 3rd year (2010, 2nd full field season) of research was very similar to 2009. The additional time will provide two full years and one fall season of data on the cover crop studies and should give more rigorous data to address the proposal objectives. Three nursery cooperators worked with project leaders implementing the proposed research in 2010. Methods of seeding cover crops were altered from broadcast seeding to, while still broad casting seed, we ran a mechanical seeder over the ground to better incorporate cover crop seed into the soil. We tried to reduce weed competition by applying a contact herbicide to the plots just prior to seeding cover crops. Sampling was conducted as described above. Again the establishment of cover crops within treatments was inconsistent. Given this inconsistency there are still patterns of differences in establishment between cover crop species and/or combinations. The best performing cover crops in the bare zone and fallow row studies include: forage radish (Raphanus sativus), crimson clover (Trifolium incarnatum ‘Dixie’), buckwheat (Fagopyrum esculentum), Austrian winter pea (Pisum arvense), and cowpea (bigna unguiculata ‘Iron and Clay’. In the open field studies, forage radish was the best but sunn hemp (Croralaria juncea ‘Tropic Sun’) and sudex (Sudan x Sorgham hybrid) also did well. Analysis of arthropod data is somewhat variable. In comparing the abundance of feeding guilds (herbivores, predators, and parasitoids) between cover crops in bare zone studies, we found patterns but the only significant difference was higher parasitoid abundance on forage radish compared to a bare ground control. Similar patterns were seen between cover crops in open field studies, except there were significantly fewer predators in forage radish than bare ground (in the fall).

As part of the cover crop bare zone tree row study a predation experiment was implemented. Black cutworms eggs (a sentinel prey item) were placed on the foliage of trees in each of the four cover crop treatments (replicated among nurseries and tree species). Our prediction was that treatments with cover crops would support a greater and/or more diverse population of predators compared to the conventional / no cover crop control treatments, and therefore egg survival should be lower in the cover crop treatments. To our surprise this is not what was found. Egg survival was lowest on trees with no cover crops on the ground below the trees, and there were no differences in egg predation between cover crop species. This would suggest that the cover crops may be acting as sink for natural enemies drawing them away from the trees resulting in greater survival in those non-cover crop treatments.

An additional soil quality experiment was added to address the question of soil loss during ball and burlap harvesting of trees in the fall of 2010. Analysis of the data on soil loss from ball and burlap harvesting study found the average amount of soil removed with a 81-cm spade was 199 kg dry wt (SE 5.12a). Measured soil rate readings were more variable using the conical spade compared to the hemispherical, especially for maple. Root weight differed between tree species (arborvitae 1.13 kg dry wt (SE 0.119); maple 2.99 kg dry wt (SE 1.78). The magnitude of root weight compared to soil weight in the root ball was trivial even though it varied by species. Results from this study should allow for the development of a simplified indirect method to quantify soil removal in nursery soils.

A field day was conducted in collaboration with the MD Nursery and Landscape Association and preliminary results of the cover crop research were presented to 96 attendees. Presentations on sustainable practices were given at green industry conferences by project leaders.

Milestones 4, 5, 6, and 7:
In the 4th year (2011) of the proposed project, discussions between the project leaders and the PBC members (via phone, nursery visits, and emails) raised questions on another practice of interest to stakeholders. The project leaders in collaboration with nursery cooperators implemented a change in the original proposal in that we decided to conduct an additional field study to evaluate the potential benefits of rotating grass allies and tree rows at time of field replant compared to replanting into original tree rows. Two nursery growers worked with project leaders implementing this research in 2011. Comparison of soil quality between grass alleys and tree rows to assess the sustainability of the two methods basically found the grass alley was superior to bare/weedy tree row after 5 years in a cluster of chemical and microbial indicators associated with higher soil organic matter, but was not consistently better in the grosser physical measures and macro-organism (earthworm) counts. Further studies are needed to better answer this question.

In 2011 a field demonstration on cover crops with an associated presentation by project leaders were presented at a field day held in collaboration with the Maryland Nursery and Landscape Summer Field Day. Eighty nine green industry professionals and extension and government personnel attended the field day. Presentations on sustainable practices also were given at green industry conferences reaching MD and regional stakeholders.

A final survey was given to attendees of the field days in March 2012 to evaluate their adoption of cover crop and other sustainable practices.

Participation Summary

Education

Educational approach:

Outreach activities:

One Nursery Field Day, “Staying Profitable Through Sustainable Field Nursery Production Practice”, was held in the fall at one of the cooperating nurseries and was attended by approximately 70 stakeholders representing nursery growers, IPM consultants, government agencies, Extension, University administration, and green industry associations. A survey was given to grower participants on their current production practices and their use of cover crops.

The second Nursery Field Day, “Sustainable Nursery Practices that Improve Your Profitability”, was held in the fall 2009 at one of the cooperating nurseries and was attended by approximately 64 stakeholders representing nursery growers, IPM consultants, government agencies, Extension, University administration, and green industry associations. A survey was given to field day participants to determine if the information presented was informative and if they were likely to implement practices / methods they had learned about that day. Five presentations on the projects progress and results, and other sustainable practices were presented.

A third and fourth field day demonstrating cover crops was conducted in summer 2010 and 2011 in conjunction with the Maryland Nursery and Landscape Association Annual Summer Field Days. There were 167 attendees to the 2010 field day and 89 at the 2011 field day.

Color handouts were created for each of the above field days that demonstrated the benefits of cover crops and other sustainable practices.

Presentations at state and regional meetings targeting green industry professionals, and extension and government personnel have been given (~350 reached)

Additional Project Outcomes

Project outcomes:

Impacts of Results/Outcomes

The verification process for this target consists of three major steps. First, there was continuous communication and interaction with nursery collaborators. Second, surveys were initiated immediately following field days. The final process consisted of a survey that was sent to participants of the 2008, 2009, and 2011 field days.

Through communication (pre and post project) with nursery collaborators it was possible to determine their satisfaction with the project, the information they learned, and their suggestions for improvement. Grower 1 was very satisfied with the project; felt he had learned a lot and made suggestions of measures to improve the project and sustainable practices (he is the one who came up with the idea of grass alley’s having higher quality soil then tree rows as a sustainable practice). Grower 2, from a larger nursery, was happy with the project, and learned some level of information on sustainable practices. Grower 3 was relatively unsatisfied with the project because in many plots within his nursery there were significant weeds – in the conventional control plots and also in the cover crop treatment plots.

In 2008, approximately 70 stakeholders attended a nursery field day, “Staying Profitable Through Sustainable Field Nursery Production Practice”, at one of the cooperating nurseries and were informed on the use of cover crops and their benefits to pest management and soil quality and other sustainable nursery production practices. Nursery growers were surveyed at the end of the event. This survey determined that participant awareness on cover crops and their benefits was considerably increased. Out of 19 stakeholders responding to the survey, 13 (68%) obtained “considerable” new information, three obtained “some” new information, and three had information they knew reinforced. Project presenters provided “excellent” to “satisfactory” information and were able to “create interest” on the topic [17 of 17 (100%) respondents rated satisfactory to excellent].

Approximately 64 stakeholders attended the fall 2009 nursery field day, “Sustainable Nursery Practices that Improve Your Profitability”, held at one of the cooperating nurseries and were informed on the use of cover crops and their benefits to pest management and soil quality, and other sustainable nursery production practices. Nursery growers were surveyed at the end of the event. This survey determined that participant awareness on cover crops and their benefits was considerably increased. Out of 11 stakeholders responding to the survey, 11 (100%) found the presentations to be highly informative, and nine (82%) stated they anticipate using the information presented. Project presenters effectively presented the material (11 of 11 respondents rated satisfactory to excellent). Presentations on other sustainable practices (ex. using sensor technology to improve water use efficiency; biodegradable pots; alternatives to glyphosate) were ranked similarly by field day participants, including two presentations by nursery growers.

A final post survey was given to attendees of all of the field days in March 2012. Surveys were sent to people as hard copies to complete or they could be completed on-line. Of the ~220 attendees to the three field days, 129 were sent and asked to complete the post survey, and 21 (16%) of those responded. Unfortunately the response rate was low. This was a three part survey: Part 1targeted practitioners such as growers or landscapes (13 responses); Part 2 targeted extension educators, consultants (three responses); and Part 3 was a catch all – other (likely government personnel) (five responses). The objective of the survey was to evaluate changes in use of cover crops (new user, expanded area) and other sustainable practices. Other factors evaluated include changes in knowledge and potential benefits gained (ex. reduced pesticide or fertilizer). The final objective of this survey was to verify that the project reached its performance target.

Unfortunately the response to this post survey was so low (only 13 practitioners responded) there is mathematically no way to estimate if 25 practitioners who have never used cover crops, are now using them. The survey does indicate that people are / will be adopting new sustainable practices in their nurseries, and more than one practice. This suggests the project has reached part of its performance target of “5 nurseries adopting one new sustainable pest or soil management practice”. Several of these practices were evaluated in our project such as: cover crops in various nursery areas (8), filling holes following ball and burlap harvest (3), top dressing (3), and rotating new tree/shrub planting into previous grass alleys (6). When those implementing some type of sustainability practice were asked if they see an increase in benefits, responses ranked from highest (combined response of somewhat and a lot, vs not at all) to lowest were: reduced soil erosion (92%); improved soil quality (85%); improved plant health (77%); economic benefit (77%); reduced need for fertilizer (69%); increased natural enemy activity (60%); and reduced need for herbicides, insecticides and miticides (55%).

Other types of people that responded to this survey include Extension Educators and other trainers (3). In this group knowledge was increased (66%) following a field day, and 100% plan on training on the use of sustainable practices and cover crops. Others included government, park, and retail garden center personnel (5). 80% felt they were more knowledgeable on sustainable practices following a field day, and 40% felt the training would benefit them in their job.

Farmer Adoption

One nursery cooperator is adopting the use of cover crops in open fields, fallow tree rows, and in bare zone tree rows in his nursery. One other nursery grower has adopted the use of cover crops. Two other nursery growers that I have communicated with were using cover crops, and now plan on expanding their use.

Assessment of Project Approach and Areas of Further Study:

Areas needing additional study

Methods towards improved establishment of cover crops in production nurseries (ex. seeding methods, weed management, irrigation).

Methods towards increasing response to post surveys.

Additional studies are needed in the comparison of grass alley to tree row for replant zone selection to determine which of these are the most sustainable practice. Studies should examine a different soil type such as a coastal plain soil, to compare grass alley soil to bare tree zone soil after normal pre-planting organic matter amendment. Measures of tree growth and health in the conventional and rotational replanting regime should be taken. A cost-benefit analysis of the two replanting options needs to be done.

A systems level, on farm approach is needed where a grower can implement multiple sustainable practices and researchers can evaluate their effectiveness.

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.