An Evaluation of Interplanted / Mulched Orchard Rows

PROJECT BACKGROUND
Sliwa Meadow Farm is a 40 acre renewable energy homestead. We are off the grid and have generated our own electricity, using photovoltaics and an electric wind generator since we moved onto the place in 1980. Using a farm windmill, water is pumped into a holding tank and flows by gravity to points of use. Our passive solar home was self-designed and built. Our farming is small scale and horticulturally diverse. We are organic market gardeners selling primarily at the Winneshiek Farmers Market, the Oneota Food Co-op, and local restaurants. Our primary crops are: tomatoes, sweet peppers, garlic, onions, winter squash, lettuce, cut flowers, pears, plums, apples, honey, and hand-dipped beeswax candles, strawberries, raspberries, jam, jelly, and fruit butters. A new project for us involves more intensive use of our fenced orchard site, which already includes young grape vines planted so they can be trained on the fence. Interplanting the orchard rows takes site usage to a higher level and will greatly diversify the orchard environment.

PROJECT DESCRIPTION AND RESULTS
Our project goals were to fully utilize the orchard site and to increase farm profitability. To meet these goals, we proposed interplanting young orchard rows with small fruits, vegetables, and flowers. We chose some crops, such as lettuce, strawberries, and gladiolas, which would be readily marketable and would grow non-competitively with fruit trees. Other crops were grown, which would provide habitat and food for beneficial parasites and predators as well as being a nectar source for our honeybees. Especially useful in this category were: Korean mint (Agastache rugosa), hyssop, New England aster and the buckwheat cover crop. The project area is a two-acre orchard of trapezoidal shape enclosed by an eight-foot-high woven wire fence. The fruit trees are a mix of pears, plums, and apples spaced 20 feet by 20 feet in ten North-South rows. The soil type of the orchard is a Fayette Silt Loam.

The project was initiated a year prior to sowing, by tilling the sod in the orchard rows with walk behind garden tillers, creating beds approximately four feet wide between each tree in the row. All the beds were sown to a cover crop of buckwheat, which set seeds and grew until frost killed.

The main market crops from these plantings were lettuce, gladiolas, and day-neutral strawberries, which produced a crop the first year. The June-bearing berry plants grew vigorously, filling the beds and hold promise of bountiful future harvests. Five succession crops of eight varieties of lettuce were grown either in full beds or interplanted in flower beds. Three plantings of gladiolas included in this project were part of five staggered date plantings around Meadow Farm.

Along with the stated goals, this project emanated from a premise that a polyculture is preferred to a monoculture from the standpoint of ecological and agricultural stability. Orchards can be sterile environments, especially when competitive ground cover is, for good reason, removed. However, I believe having a non-competitive ground cover using both mulch and plants, has benefits. Biologically, such a cover provides for and enhances beneficial soil microbes in the tree root zone, which is fundamental to the functioning of the soil food web and tree health. The cover also protects the surface soil from erosion, and can be desirable habitat for beneficial parasites and predators. When marketable crops are used as part of the ground cover, there is the opportunity to increase farm profitability using the same land base. Additionally, orchards with interplanting are aesthetically enhanced and are more interesting places in which to work. Polyculture cropping systems are often characterized by lower pest pressure and enhanced soil vitality.

This project was set up as a demonstration of interplanting young orchard rows with small fruits, vegetables, flowers, and cover crops. Establishing and managing such a cropping system has led us to the following observations:

1. Tilling around established trees and breaking sod with walk-behind garden tillers is difficult and time consuming. It would have been easier and more efficiently done with tillage field equipment prior to establishing an orchard.

2. We plan to manage the established beds without additional tillage by keeping them in permanent mulch and/or cover crops and planting into small areas cleared of mulch. This practice will allow cropping without soil erosion, and the continued mulching should increase soil organic matter content over time.

3. The diversity of crops in the orchard and color of the flowers all season long is esthetically very pleasing, enhancing the beauty and interest of the site. We certainly experienced an uplifting feeling when working in the interplanted orchard over and above the joy we get from watching a developing fruit crop throughout the season.

4. Large numbers and many species of butterflies were present thoughout the season. Insects generally were present in large numbers, and although no sampling was done, we assume some were beneficial predators and parasites of fruit pests. However, pests may also find the cover crops and/or mulch to be favorable habitat. This possibility underscores the need to sample arthropod (including insect, mite, and spider) populations in the various habitats to quantify the beneficial/pest levels. This knowledge will allow informed management decisions, which favor beneficial arthropod habitat and eliminate pest arthropod habitat. Other considerations of beneficial and pest arthropods are discussed by Bugg and Waddington in a 1993 University of California Sustainable Agriculture Research and Education Program review article titled, “Managing cover crops to manage arthropod pests of orchards.” [See: http://www.sarep.ucdavis.edu/newsltr/v5n4/sa-12.htm]

They conclude, that ample documentation shows various cover crops are home to distinct groups of beneficial and pest arthropods existing in diverse nutritional relationships. They point to the need for replicated trails to evaluate how cover cropping and crop species composition and management affect orchard microclimate and tree nutritional status, and in turn, how those conditions influence pest dynamics. Awareness of these ideas encourages us to a least be very observant of arthropod activity, to identify species and to document population levels.

5. The lettuce crop was especially productive, likely benefiting from the shade and protection of the fruit trees and flowers. This effect seems especially important in the high heat of summer.

6. A slight drawback in areas where fruit trees were sprayed with the kaolin clay product, Surround, was the interplanted crops were obstacles in walking around the trees with a hand held sprayer, and were subject to some spray drift and drip. In the future, we plan to make trapping our primary insect control technique thereby reducing or eliminating sprays. Cover crops will be sown around plum trees where sulfur will continue to be used in controlling brown rot.

7. All fruit trees have two-foot-high ¼-inch-hardware-cloth trunk protection and are mulched with wood chips. This along with hay and/or straw mulch in the interplanted beds has significantly reduced weed competition and the mowing which was done previously. Although no measurements of competition were taken, we feel that the crops grown had less negative impact on the fruit trees than the highly competitive sod grass present prior to tilling and cropping. Certainly an essential next step in evaluating an intercropping system would be a quantitative measurement of crop and fruit tree compatibility.

In an Ohio State University study report in "Fruit Growers News," May 2002, of interplanting various berries beneath apple trees; lingon berries, and honeyberries as well as the apples produced good crops. Raspberries and jostaberries produced well, but the apples failed to set a good crop. Apparently, certain interplanted crops may have a negative impact on the fruit trees and therefore caution needs to be advised in choosing crops for interplanting in an orchard. [Editors note: The article about the Ohio State University study on interplanting berries is included at the end of this report.]

8. Although not envisioned at the start of the project, we now view the project site as a garden in which the fruit trees are one of the crops vs. an orchard where other crops are grown. This concept has led us to consider expanding the cultivated area, i.e. alternate alleys could be cropped thereby increasing production of the site still further and also improving the diversity of crops to yet a higher level. The alleys don’t necessarily need to be sown with market crops entirely, but could be partially in a cover crop such as a legume, which while in bloom, could be a good nectar source for the bees as well as for beneficials; and in the long term, would add nitrogen to the site and also would reduce mowing of the competitive grasses. Possible cover crops could be a low cover such as Dutch white clover or field peas and/or hairy vetch, or a mix of all of these. The uncultivated alleys would allow vehicle access to all trees and beds.

An additional observation was made because the project area is within a fence. Fence posts can serve an important function in pest control. We have noticed, perched on the tops of the orchard fence posts, red tailed hawks, which likely were hunting the abundant gophers plaguing the orchard trees and crops. We do have bird houses on some fence posts and have seen blue birds and swallows catching insects in flight. We intend to encourage birds by installing more bird houses and plan to put up bat homes as well.

We were fortunate to have key individuals assist us with this project. Beginning with the application process, Andrew Johnson, coordinator of the Resource Conservation and Development for Northeast Iowa, provided helpful suggestions and submitted a letter of support for our proposal. The Winneshiek County Extension office helped advertise our field day, primarily through the Master Gardeners Network.

Ketel Paulsen, a local gardener, contributed to the project by cropping fifteen beds in the youngest part of the orchard with vegetables in various combinations. His plots were a great example of highly productive intensive gardening.

Matthew Blom, a student gardener, cropped two beds using a method of minimal maintenance after broadcasting “seed balls,” clumps of assorted vegetable seeds and soil. This technique had limited success, but had low disruption of soil structures and soil biota. The experiment encouraged Matthew to study how this technique was successfully employed by Masanobu Fukuoka and his followers as described initially in One Straw Revolution, published in 1975. Matthew described some of these ideas at the field day.

Our field day was greatly enhanced by the presence of two veteran organic orchardists: Keith Kozub of River Falls, Wisconsin and Maury Wills of Adel, Iowa. Keith gave a demonstration of apple maggot fly control using sticky real apple traps. His techniques used the proven red sphere coated with a sticky substance to catch apple maggot flies. By using real apples punctured through by a wire hanger, the apple essence is emitted, which attracts the flies. Keith’s presentation included in-depth information on the biology and behavior of the apple maggot. This prompted us to ask what role the interplanted flowers, vegetables, and berries might play in affecting, ether positively or negatively, the population dynamics and behavior of this insect. Subsequent to the field day, Keith informed us that recent research indicates that black spheres about 2 ½ inches in diameter may improve apple maggot catch by as much as 20 percent.

Maury, who is also the organic program coordinator for the Iowa Department of Agriculture and Land Stewardship (IDALS), concluded the field day with an evaluation of interplanting. (Editor’s Note, September 2005: Maury Wills is currently the Bureau Chief of the Agricultural Diversification and Market Development Bureau at IDALS.) He noted the compatibility of the wide tree spacings, which provided for excellent sun and drying air penetration of each tree with cropping of the open space between trees, especially in a young orchard. He stressed the need to carefully select interplanted crops, which would not compete adversely with fruit trees crops; wondering particularly if certain crops might change soil chemistry, which would be either beneficial or detrimental to fruit trees. He suggested soil testing might be insightful in this regard. He also suggested that in the future, we might want to do some insect sampling and identification to know what insects are present. Has our diverse environment attracted beneficial insects? These issues are addressed in our list of observations in this report, as well as in our future plans for managing the interplanted beds.

PROJECT IMPACT
As a result of our field day, we were able to identify a group of regional growers, who were interested in trying orchard interplanting and/or were intrigued with this project, with whom we are in the process of establishing a network and organization for sharing ideas and management techniques for organic and sustainable tree fruit production. This newly emerging group is dedicated to promoting ecologically responsible and sustainable orchard management through workshops, field days, and publications.

OUTREACH
Our primary outreach activity was hosting a field day highlighting the interplanting project. We were able to combine this event with the annual summer meeting of the Upper Midwest Organic Orcharding Association and a monthly gathering of the local Winneshiek Farmers Market farm tour and potluck on the same date. This dovetailing of events resulted in a fairly large turnout of over seventy individuals. By coincidence, a local and regional newspaper ran stories about us and our farming just prior to the field day, which brought out many attendees. We will continue to experiment with interplanting in the orchard rows and will seek out opportunities to share the results of this project with other growers at meetings and field days.

[Editors note: The following article by Bill McNutt was published in "Fruit Growers News" on May 2002. For more information, visit the "Fruit Grower News" website at: http://www.fruitgrowersnews.com/]

The Fruit Growers News
May 2002

By Bill McNutt
Ohio Correspondent &
Dr. Martin Quigley
Ohio State University

If apples and berries are grown together, would this be of greater value per land unit compared to when each crop is grown alone. Can fruit trees and berries be part of landscaping design. Ohio State University (OSU) research aims to find out.

Both commercial fruit growers and landscape architects may soon be benefiting from this recently completed research at the Ohio Agricultural Research and Development Center (OARDC). This “best of both world’s” research scenario was devised by Drs. Martin Quigley and Joe Scheerens, OSU/OARDC Department of Horticulture and Crop Science, and carried out by PhD candidate Tina Rivera at the Wooster location of OARDC from 1998 through last year.

Various berry crop combinations were planted under stand alone apple trees - in this experiment the semi-dwarf Goldrush variety. Two spacings, one grower recommended, the other slightly more compact, were used for the berry plantings.

During the three-year trial period, the outdoor berry plantings were duplicated in pots under greenhouse conditions, and shrub root growth measured through windows in the pots. In both locations, root growth averaged about seven inches, while tree roots went down about 40 inches or more, limiting competition for nutrients to the soil surface. In addition, ground cover provided by small fruit growth did provide considerable weed control, while overhead shade provided by the trees did not hamper production of two of the four berry species that were selected in part for their shade tolerance.

Two combinations were used as the ground crop planted under the apple trees: a mix of blackberries and josta berries (a cross between black currants and gooseberry), the other combination included lingonberries and honeyberries. While the blackberry/apple and josta/apple mixture produced copious quantities of berries, they did so at the expense of the apple trees, which did not set or develop any fruit. According to Quigley, these fruits are suited to full sun, which will grow better by themselves. They are also more competitive at both the root and nutrition level with the trees,

The real champion of this two-pronged cultural approach was the lingonberry/apple and honeyberry/apple grouping which grew and produced well under tree shading, while the trees yielded a slightly lower than normal apple harvest. Lingonberries are of Scandinavian origin, and prefer less sun, even growing better in the more confined spacing,

Honey berries meet the same criteria, and are native to Siberia, at approximately the same latitude as that of North Dakota and Nebraska. Shading is not a problem with either crop. Successful double cropping is feasible, in Quigley’s opinion, though a successful enterprise probably depends on labor availability, since machine harvesting would be almost impossible.

Quigley feels such a growing system would lend itself to any u-pick operation, since all the crops involved follow in a natural pattern. Honeyberries are first to bloom in the spring, followed by lingonberries and of course apples in late summer and early fall. He doubts that blackberries will work as part of a double crop system, since they require so much maintenance and grow higher into the apples. Josta berries, on the other hand, are much easier to work with and make a nice shrub for both flowering and fruiting effect. He recommends growing them as a bearing ornamental and using for landscaping.
While this research project has concentrated on commercial plantings, the implications for landscape architecture are obvious. Quigley is also promoting the American native black choke - cherry as one possibility to combine with lingonberry culture. Ligonberry is recommended for both juice and medicinal purposes, given recent OSU horticultural/medical research on the cancer inhibiting properties of certain small fruits. Brazilian passion fruit has become a major ingredient in the increasingly popular tropical drinks. Using lingonberries or choke-cherries as an additional ingredient could expand marketing opportunities. All these provide green ground cover and need shade which trees would offer, while also providing an attractive landscape.

Quigley pointed out that honeyberries are related to honeysuckle, with the possibility of densely rooting shrubs becoming ornamental and fruiting erosion control plantings. Grown in a standard manner, the soft sweet blueberry-like fruit of the honeyberry could also become part of u-pick, as well as a component of an “edible landscape.”

Midwest homeowners would have the option of using trees and shrubs in combination with small fruit that make great landscaping, but would taste good when harvested - just like Southern residents who can pick oranges and grapefruit out of their backyards.