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Comprehensive Integrated Agroforestry

(Multi-Level Forest Farming at Red Fern Farm, Created 2003)

Comprehensive Integrated Agroforestry is a project funded in part by grants from NCR SARE and Practical Farmers of Iowa. It is a highly flexible, intensively managed system of sustainable agriculture. The system combines several different Agroforestry practices including forest farming, alley cropping, riparian buffer strips, shelterbelts, silvopasture, and a few others which have not been named or even considered by the world of academia.

The system uses a mosaic of fruit/nut bearing trees and shrubs planted in 1/10th acre blocks, one species to a block. Adjacent blocks contain different and preferably unrelated species.

The species blocks contain a tree population sufficient to supply the cross pollenization required for fruit and nut set, and each block is large enough to manage as a unit. At the same time the blocks are small enough to allow the planting of up to ten different species of trees per acre. This high biodiversity prevents the pest and disease problems which would have been invited by a larger monoculture.

Species blocks consist of one-hundred foot long lengths of a pair of rows spaced 20 feet apart. Tree spacing within rows is dependent on the species, and ranges from five to twenty feet. As the trees grow larger, they will be thinned to maintain high fruit/nut production. Most of the tree species will be pruned to a clear trunk up to a height of eight to twelve feet above ground to allow for production of high quality timber for lumber, veneer, or fuel.

Between and underneath the trees high value medicinal herbaceous perennials such as ginseng, goldenseal, and Echinacea are interplanted into the existing vegetation. The herbaceous ground cover protects the soil from erosion while the trees provide the shade required by the ginseng and goldenseal. The Echinacea is not dependent on shade and is planted between tree rows.

During the early life of the planting, vegetation is controlled by mulching immediately around each tree, and by mowing two to three times per year between trees. Once trees become large enough to withstand browsing, livestock grazing may be used. The ground cover may provide forage while the livestock crop the vegetation low enough to make nut harvesting easier.

In his classic book Tree Crops, J. Russel Smith describes what he called two story agriculture (now called "alley cropping") in which crops were planted between rows of nut bearing trees. Comprehensive Integrated Agroforestry takes this idea a few steps further, to what I call "four story agriculture". Intensive management is applied and crops are harvested at four levels: medicinal roots from underground, livestock forage and/or medicinal plants at ground level, wood from the tree trunks up to about twelve feet, and at the fourth level the fruit, nuts, and leaves are produced.

The species blocks are grouped together in units of one to four acres on fairly level ridgetops between drainages. The steep slopes of the drainages are heavily wooded with native forest, and serve multiple purposes, including shelterbelts for protection of the tree plantings, riparian buffer strips, and travel corridors for wildlife.

The Agroforestry planting itself is excellent habitat for wild plants and animals, including a wide variety of woodland and savanna wildflowers, and wildlife ranging from red bats and treefrogs to deer, turkeys, and coyotes.

The exact combination of species used in the CIA system must be matched to the specific site, and no two will be exactly alike. The species I used on my farm in Southeast Iowa include:

Black Walnut (Juglans nigra) - Named cultivars of black walnut were used, and whenever possible, were grafted onto saplings which already existed on the site. The cultivars tend to produce annual heavy crops of high quality nuts, i.e. large, thin-shelled nuts with a percent kernel two to four times higher than ordinary walnuts, and which crack out kernels in quarters or halves. In well-managed orchards, the cultivars average about one thousand pounds per acre. A few individuals may be capable of bearing up to five thousand pounds per acre. Black walnuts may wholesale for 10ข - 25ข per pound. Kernels retail for $8 per pound or more. A well-managed black walnut log harvested at fifty years old may be worth more than all the nuts harvested in the interim.

Chinese Chestnuts (Castenea mollisima) - this is the blight resistant relative of the American chestnut. Chestnuts may begin bearing as early as three years after planting. At maturity, they may produce up to two to four thousand pounds per acre, and wholesale for $1 - $3 per pound. Chestnuts are in very high demand worldwide and in the United States.

Hybrid Hazels (Corylus americana x avellana) - This strain was originally bred by Carl Wescke and developed by Philip Rutter. These shrubs tend to bear very heavy crops of medium sized, thin-shelled nuts. Philip Rutter had yields reaching five thousand pounds per acre in 1996, and production is still increasing. Hazelnuts wholesale for 40ข to $1.00 per pound.

Pecans ( Carya illinoensis) - These are northern pecan varieties, smaller and better tasting than southern pecans, and capable of ripening nuts in a shorter growing season. I have no data on northern pecan productivity, but I believe it is rather low.

Shellbark and Shagbark Hickories (Carya laciniosa and Carya ovata) - As with the black walnuts, grafted varieties with larger, thinner-shelled, better cracking nuts were topworked onto existing saplings whenever possible. These hickories bear even less than pecans, but many people believe they are the best tasting nuts in the world.

Heartnuts (Juglans ailantifolia var. cordiformis) - The heartnut is a sport of the Japanese walnut producing a flattened, valentine heart-shaped nut with a fine, delicate flavor. The kernel cracks out easily whole or in halves. The tree is very fast growing and heavy bearing. Trees are reported to bear one hundred pounds by the age of seven or eight years. Heartnuts are eagerly purchased by consumers even at $3 per pound. Hardiness and disease problems limit the viable growing regions for heartnut.

American Persimmon (Diospiros virginiana) - Most American persimmons are small and seedy, but the grafted varieties I used bear larger and higher quality fruit. The scientific name for persimmon means "food for the gods". Ripe persimmons are among the sweetest fruits in the world. There are a few companies which buy persimmon fruit and market persimmon pulp to gourmet restaurants.

Pawpaw (Asimina triloba) - For some reason, this native fruit is not well known, even in areas where it is plentiful. This small tree produces a green-skinned fruit about the size and shape of a small potato. It tastes like a cross between banana and cantaloupe, hence the nickname "prairie banana". The few growers of this fruit report demand always exceeds supply. A market for pawpaw fruit in the near future may include the pharmaceutical industry. A researcher recently discovered a powerful anticarcinogenic chemical which is concentrated in the unripe fruit.

Nut Pines (Pinus koraiensis and Pinus siberica) - These pines are closely related to the North American white pines, but they produce a large edible nut similar to the pinion pine of the southwestern U.S.. The delicately flavored pine nuts are considered gourmet food and retail for $15 per pound or more.

Ginkgo (Ginkgo biloba) - The Ginkgo tree is slow to come into bearing (20 years or more) but makes up for it by producing two crops at the same time. The fruit kind of resembles a wild plum but has a foul odor. Inside the fruit is a one-inch long nut, which is highly valued in oriental communities. Well-cleaned nuts may sell for three or four dollars per pound. The leaves are another potentially lucrative crop from the ginkgo tree. Demand for ginkgo extract is increasing rapidly worldwide, and dried leaf will wholesale for over $5.00 per pound.

Herbaceous Perennials:

Ginseng (Panax quinquefolia) - This is one of the most highly valued medicinal plants in the world. In the fall of 1996 local collectors received $550 per pound for wild ginseng root (dry weight). The price for wild roots has since dropped to about $200 per pound due to the Asian financial crisis, but it is still a potentially lucrative crop. Ginseng requires about 70% shade, such as that produced by forest trees. Ginseng plantings may produce anywhere from three hundred to three thousand pounds per acre of marketable root in three to ten years, depending on the growing method used. The value per pound of the root may range from about $50 to about $200, again depending on the growing method.

Goldenseal (Hydrastis canadensis) - This is another forest medicinal plant requiring the same shade and soil conditions as ginseng. They are often found growing together in the wild. Goldenseal may produce anywhere from five hundred to two thousand pounds of marketable root per acre in three to five years, depending on intensity of cultivation. The value of the root is between $20 to $30 per pound regardless of the method used to grow it. The tops of the plant are worth $8 - $10 per pound, and may account for one third of the value of the crop.

Purple Coneflower (Echinacea purpurea) - A very adaptable medicinal plant. It may grow under forest shade or in full sun, but thrives best in partial shade. This plant is ideal for ally cropping between rows of trees. This plant grows much faster than ginseng and goldenseal, and may mature in two to three years. The yield of dry root may be one thousand pounds per acre or more, with a value of around $24 per pound.

Some other plants which may be incorporated into the system in the future are: Kiwis (Actinidia sp.), Maypop Passionflower (Passiflora incarnata), Grapes (Vitis sp.), Medlar (Mespilus germanica), St. Johnswort (Hypericum pyramidatum).

Some of the advantages this Agroforestry system has over conventional agriculture include:

• Negligible soil erosion, less than 0.02 tons per acre, compared to eleven tons per acre for nearby corn and soybean fields.

• Increased water infiltration and reduced runoff due to well-maintained soil structure.

• Low or no need for chemical fertilizer and pesticide inputs.

• No need for expensive, high tech. equipment.

• Very low fossil fuel consumption compared to conventional row crop production.

• Energy balance, i.e. the system will "produce" more energy than it consumes in inputs, compared to conventional corn production which consumes 12 - 20 calories of energy for every calorie produced.

• More efficient use of solar energy. The perennial plants in this system will leaf out and begin converting solar energy to useful plant material at least six weeks earlier in the spring as compared to corn and soybeans. The Agroforestry system will continue converting solar energy for another four to six weeks in the fall after the corn and soybean plants have died.

• Carbon sink, i.e. the woody perennials in the system take carbon dioxide (the most important "greenhouse gas") out of the atmosphere and put it into long term storage.

• High biodiversity, with up to ten species of trees per acre as well as hundreds of species of wild plants and animals will prevent the build up of serious pest and disease populations.

• Excellent habitat for wild plants and animals is found year round in the Agroforestry system.

• The system is relatively stable and durable. Once established, the system could maintain and regulate itself for many years without annual plowing, planting, fertilizing, cultivation, or any other human interference.

• The system has high profit potential from a small area of land (more than $20,000 per acre per year at maturity), making possible more, smaller, yet more prosperous farms on a given area of land.


The Comprehensive Integrated Agroforestry system does have some serious disadvantages:

• Establishing the system is very labor intensive and time consuming.

• It may take several years investment in labor and capital before the first returns are seen.

• The break-even point may not be reached for seven to ten years.

• The mature level of production may not be achieved for as long as twenty years.

• Markets for some of the products are not as well established. You can't just take a load of chestnuts down to the local elevator and sell them.

• The biggest problem seems to be overcoming the paradigm of agriculture in most people's minds in which large monocultures of annuals must be planted in the spring and harvested that fall.

My Comprehensive Integrated Agroforestry project is still in the early stages of establishment. It will take years to develop and mature. It will take even more years to prove it is a viable alternative to conventional row crop agriculture. Some of the disadvantages of the system will prevent it from ever being accepted by some people. In spite of all this, I am confident Comprehensive Integrated Agroforestry will prove to be at least an important part of the solution to the problems with conventional agriculture.

Tom Wahl
Red Fern Farm
Wapello, Iowa


Financial Projections

The following are first year cost per acre projections for establishing a mixture of fruit/nut trees. They assume no brush/tree clearing or ground cover seeding costs. They also assume each tree will be protected with 3-foot tall open mesh tree shelter and bamboo stake, and with a woven polypropylene landscape cloth mat 3’ x 3’ square. Each mat would be staked down at all four corners with 6" ground staples.

In the case of direct seeding, two seeds would be planted at each site and if both germinated only the better of the two would be retained. Each seeding site would be protected from rodents with at 1’ x 1’ square piece of standard poultry netting ("chicken wire") staked down at all four corners with 6" ground staples. This is in addition to mats and tree shelters.

Tree spacing would be 10’ x 20’ for seed or seedling (except for hazels) and 20’ x 20’ for grafted trees. Hazels are spaced 6’ apart and rows alternating 10’ and 15’ apart.

Annual maintenance costs for all but hazels and grafted trees are estimated at $100/acre per year for tree and material replacement, fuel, Tree Guardฎ deer repellant, and miscellaneous, plus 6 hours labor. Costs for grafted trees and hazels are estimated at $200 per acre per year. Labor would be 6 hours per acre for grafted trees and 12 hours for hazels. After 5 years, maintenance cost would be expected to be lower.

Costs per acre at 2003 Prices

Direct Seed    
400 seeds @ 10ข each

200 nets and staples @ 35ข per unit

200 poly mats & staples @ $1.25 each

200 stakes & shelters @ 30ข each

20 hours labor







$420/acre + 20 hours labor

Yearly maintenance = $100 + 6 hours labor


Bare-root Seedlings
200 seedlings @ $2.00 each 

200 poly mats & staples @ $1.25 each

200 stakes & shelters @ 30ข each

20 hours labor






$710/acre + 20 hours labor

Yearly maintenance = $100 + 6 hours/ labor


Container Seedlings
200 seedlings @ $3.00 each 

200 poly mats & staples @ $1.25 each

200 stakes & shelters @ 30ข each

20 hours labor






$910 /acre + 20 hours labor

Yearly maintenance = $100 + 6 hours labor


Grafted Trees
100 trees @ $20.00 each

100 poly mats & staples @ $1.25 each

100 stakes & shelters @ 30ข each

20 hours labor






$2,155 + 20 hours labor

Yearly maintenance = $200 + 6 hours labor


Hazels (Badgersett)
600 seedlings @ $4.00 each

600 poly mats & staples @ $1.25 each

600 stakes & shelters (18") @ 15ข each

60 hours labor






 $3,240 + 60 hours labor

Yearly maintenance = $200 + 12 hours labor


Income Projections at Maturity

Years to Wholesale Pounds/Acre/ Gross/Acre/
Variety Maturity Price/Pound Year Year
Black Walnut 25 nuts: 10 - 60 1,000 $100 - $600
50 Lumber/veneer 100 board feet $300
    $3/board foot   Total for Walnut
        $400 -$11,000
Chestnut 15 - 20 nuts: $2 - $4 2,000 $4,000 - $8,000
Hazelnut 6 - 7 nuts: 40ข - $1 2,000 $800 - $2,000
Heartnuts 8 - 10 nuts: $3.00 3,000 $9,000
Pawpaws 15 - 20 processed fruit 2,500 $10,000
  puree: $4.00    
 Persimmon 15 - 20 processed fruit 2,500 $10,000
  puree: $4.00    
 Ginseng (wild simulated) 10 - 15 root: $300 10 $3,000
 Goldenseal 5 - 9 root: $25 400 $10,000


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