The Kerr Center for Sustainable Agriculture has developed a large-scale method of tree establishment for agroforestry plantings that integrates a timber production component into a cattle grazing operation. The method is site adaptable, environmentally safe, cost efficient, and can be implemented with tools already present in the agricultural operation. Maximum use is made of on-farm inputs. There are synergistic biological interactions between the trees, cattle, and productive capacity of the site.
The key to the tree establishment method is the formation of mulched contour tree rows at spacings which facilitate future management, maintenance, and production objectives. The mulched contour tree rows control forage competition; cycle and supply nutrients; improve soil moisture, air, and biological levels; reduce erosion; increase diversity; and provide wildlife habitat. The wood products provide a long-term, income-generating opportunity, and the tree component increases and sustains pasture productivity.
The Kerr Center has obtained good tree survival and a good rate of tree growth on the 65 acres planted with this method of tree establishment. The method has widespread application for timber and cattle agroforestry systems. It remains unlikely, however, that such strategies will be adopted widely by farmers until demonstration proves that they can be integrated profitably into working farms and ranches.
Like many other southern region cattle producers, the Kerr Center has large pastures cleared of trees and maintained in that condition for hay and forage production. Producers with treeless pastures find that during heat stress, cattle do not graze well in unshaded areas. Establishing trees in these pastures provides shade for cattle and allows for more even grazing. It also helps to remove excess water, which can be a limiting factor for high-quality forage.
Agroforestry Research Projects
In 1991 a multi-disciplinary team, with livestock, forestry, agricultural economics, and environmental expertise, designed and implemented two large-scale timber and cattle agroforestry projects on the Kerr Center ranch. The emphasis thus far has centered on developing a cattle compatible tree establishment method which uses on-farm inputs and only equipment presently available on most farms. This tree establishment method can be easily modified to suit soil and water conditions and the needs and desires of landowners.
The two projects have the same objectives:
- to develop profitable agroforestry systems that fit easily into established farming systems
- to maintain records of capital investments and variable costs for establishment and maintenance
- to track production from timber, cattle, and other enterprises
- to monitor the effects of timber and cattle management on soil conditions and farm productivity
- to provide a working agroforestry demonstration for regional farmers, and
- to increase, enhance, and diversify the wildlife population and habitat
A unique feature of these projects is the establishment and maintenance method of the timber component. We mowed the forage present at the sites using a sickle bar mower and windrowed the forage to tree contour lines from both sides with a side delivery rake. The mowing and windrowing built up a thick matt of mulch on the tree contours into which the tree seedlings were planted during the winter. The mowing also removed the overburden of summer grasses allowing the more palatable cool-season legumes and grasses to grow better.
Between the Lakes Agroforestry Project
The project area is a steep, 34-acre, north-facing, improved grass pasture. It is situated between two lakes (Beaver Lake and New Lake) having elevations of 448 ft. and 500 ft. It has rounded dry knolls and some flats with excessive moisture. Soil erosion was a problem on this site.
In September 1991, we cut the forage in the pasture with a sickle bar mower and windrowed the cut forage into tree contour lines with a side delivery rake. In some areas of the pasture, we were unable to create a thick mat of mulch, so we unrolled 28 round hay bales (1300 lb) in sections of the rows.
In January 1992, we divided the pasture into three management areas based on topography, soil type, and moisture regime gradients. on the higher, more marginal slopes, we planted 1171 improved loblolly pines (Pinus taeda). on the two lower, more productive areas, we planted 344 sycamore (Platanus occidentalis) and 620 green ash (Fraxinus pennsylvanica) in separate contour rows. We planted 2896 black locust (Robinia pseudoacacia) around them as a barrier to limit cattle damage. The black locusts also serve as training trees to improve the form of the sycamore and green ash and provide nitrogen through nodule fixation.
Loblolly pines are used for paper and lumber. Sycamore is used for furniture and butcher blocks. Green ash is used for furniture and sporting goods. Black locust is rot resistant and is used for posts and fencing wood. We planted locally-collected rooted willows (Salix nigra) along the lake margins, hoping to satisfy the beavers' appetites before they reached the hardwood planting. We hand planted seedlings with dibble bars. Each winter from 1993 to 1995 we replaced any dead trees with seedlings of the appropriate species.
After planting, the total tree row acreage was 5, and the total pasture acreage was 28. In May 1992, we cut the forage in the wide alleys (56 ft) and windrowed the cut forage from 9 ft on each side into the tree rows. From 1992 to 1995 we hayed the project each spring and brush-hogged the edges of the tree rows. Each fall we brush-hogged the pasture.
Grazing tests with mature cows were conducted each year to observe the cows' behavior and compatibility with the trees. Beginning in winter 1996 we began the maintenance and use phase of the project. We "flash" grazed the pasture for two days with 100+ cows and their calves as they hit the area in their normal rotation pattern.
Establishment costs from 1992-95 were about $2240 or $66/acre. This includes site preparation, seedlings, and labor. Survival of trees thus far has been good (70%+) with green ash at almost 100%. Average 5-year heights for species planted: pine - 6 ft, sycamore - 9 ft. green ash - 9 ft, and black locust - 16 ft. The beavers cut one green ash tree and one sycamore tree. The willows planted along the edge of the project to satisfy the beavers' appetite were heavily grazed several times during each summer and winter.
We are getting good diversity in the tree rows from wild (free) trees becoming established naturally, mostly as root sprouts. Wild trees established in rows so far include green ash, persimmon (Diospyros virginiana), willow oak (Quercus phellos), winged elm (Ulmus alata), sweetgum (Liquidambar styraciflua), sycamore (Platanus occidentalis), thornless honey locust (Gleditsia triacanthos var. inermis), honey locust (Gleditsia triacanthos), and a few pecans (Carya illinoensis).
We are on a long-term program of soil testing in tree rows, the areas between tree rows, and control areas for plots representing distinct soil types. Soil sample report information has been prepared by the Kerr Center Soil and Plant Analysis Laboratory.
The green ash were not damaged by the cattle but have received considerable damage from deer. They immediately send out new shoots and recover nicely. The improved loblolly pines were attacked by pine needle rust, girdling beetles, tip moths, and sawflies during the summer of 1994.
These attacks were severe enough to limit height and mass growth and resulted in the death of 21 trees. In 1995 we had some disease and problems but not as severe as in 1994. In 1996 there was very little bug damage. Large numbers of beneficial insects are now present including parasitic wasps, spiders, ladybugs, praying mantis, and lacewings. We lost some of our sycamores to blackberry virus. The black locust have received very little damage.
Cattle grazed the project, as follows: 120 ADU's (animal daily units) in 1993 and 231 ADU's in 1994, 700 ADU's in 1995, and 1820 ADU's in 1996. With the "flash" grazing maintenance and use strategy there has been little tree damage to the hardwoods or pines.
We are observing an increase in the native grass component with Big Bluestem (Andropogon gerardi) and Eastern Gamagrass (Tripsacum dactyloides) becoming established in the least grazed areas. Orchard grass (Dactylis glomerata) and Broomsedge Bluestem (Andropogon virginicus) are increasing in the most heavily grazed areas. An erosion scar which was a precipitating factor in the project's location has grassed in and healed over nicely. We planted bald cypress in the pools of the erosion scar that didn't grow grass because of shallow water table conditions. No overflow from New Lake has occurred since a new spillway was constructed.
Interest in this tree establishment method continues to increase. Talks have been presented at multiple events including the Forest Trust Confabration and The Society of American Foresters Annual National Convention. Several tours were also given to landowners. This project was featured on the Kerr Center's 1995 Farm Field Day which had 105 interested persons in attendance including farmers, ranchers, scientists and other agriculture professionals. This project received international exposure as part of a presentation at the Russian Academy of Sciences and has been toured by farmers from Russia and extension agents from Haiti. This project formed the basis of a method paper in proceedings published by the Society of American Foresters.
The project site attracts wild turkeys because of its species diversity and its position between their safe roosting areas and the wildlife food plots where they feed. Flocks of more than 50 turkeys have been observed here. Snakes, bobcats, eagles, and hawks keep the rodents at acceptable levels. Coyotes, deer, possums armadillos and raccoons use the area at night.
The most important things we have learned, besides the overall effectiveness of mulched contour tree rows were:
1. Single rows of trees fit into the mechanical management of the forage-mulch operation much better than multiple tree rows or more complicated tree configurations. If configurations other than the single row method are desired, a single row can be established the first year and additional rows can be added on either or both sides the next year.
2. Leaving tree rows in a rough, natural condition provides habitat for mice and rats which allows them to harvest cocklebur seeds and other weed seeds in the field. Mice and rats have eliminated cockleburs in this previously infested field.
3. The trees that were most compatible with cattle during the early years of growth were the green ash and black locust.
New Fescue Agroforestry Project
The project site is a wet, 39-acre, flat bottom next to the Poteau River, which occasionally floods. The soil is a silt loam. The elevation ranges from 460 to 462 ft above sea level. The wetness of this pasture limits the use of machinery until late in the growing season and controls the type and amount of forage produced. A ditch around the pasture and several cross ditches provide adequate surface drainage unless they are overloaded by excess water from river flooding or beaver dams. We want the trees to dry up the pasture and improve the forage and usability of the site.
The alleys between the tree rows are 90 ft wide to make mechanical maintenance and haying easier. In September 1992, we mowed the pasture and baled the hay into 96 round bales (1300 lb). Then we unrolled the bales in the tree rows.
In January 1993, we hand planted 2000 willow oak (Quercus phellos), 1000 pin oak (Quercus palustris), 1000 green ash, 250 bald cypress (Taxodium distichum), and 100 each of Shumard (Quercus shumardii) and Nuttall (Quercus nuttalli) oaks. In 1994 we hand planted 2000 pin oak, 1000 shumard oak, 1000 green ash, and 100 bald cypress trees to form a second row in our configuration and to replace any dead trees. In 1995 we hand planted 500 green ash to increase tree numbers and fill any gaps we found in the tree rows. Most green ash were along the sides of the drainage ditch to give beavers something to eat before they reached the other trees.
We have planted 9150 trees on this project. All of the trees except the green ash and bald cypress are considered red oaks by the timber industry and thus could be sold as a single uniform unit. Red oaks are used for furniture and always in high demand from a marketing position. Bald cypress is used for decorative paneling and has some rot resistance properties.
After planting in 1995, the total tree row acreage was 4, and the pasture acreage was 35. We hayed the alleys and brush-hogged the edges of the tree rows each spring. Round hay bales were moved to a storage yard and fed to the cattle herd in the winter. In the fall of 1994 and 1995, we mowed the alleys and left the forage lying in the pasture.
From 1992 to 1995 cattle grazed the pasture during the fall and winter months when the trees were leafless and dormant. Beginning in winter 1996 we began the maintenance phase of the project. We didn't graze this project in 1996 because we wanted to encourage height growth which had been limited by yearly grazing of the terminal buds.
Results to Date
Except for the willow oaks, which were not dormant when planted, tree survival has been good. The 1996 average heights of trees in this project are; willow oaks - 6 ft., pin oaks - 6 ft., Nuttall oaks - 5 ft., Shumard oaks - 5 ft., green ash - 6 ft., bald cypress - 6 ft. Beavers damaged only the green ash along the drainage ditch as expected. No insect problems were observed. Free wild trees establishing in the rows thus far are mainly persimmon and green ash.
Establishment costs from 1993-95 were about $3500 or $90/acre. This includes site preparation, seedlings, and labor.
The mulched tree rows catch and hold a tremendous amount of eroded soil (humus, clay, and silt). The cumulative effect of this ongoing process should be an increase in the comparative elevation of the tree rows. A rise in the elevation would benefit tree growth. The project site was a favorite of the woodcocks because of an increased worm population in the soil. Flocks of more than 150 ducks used the pasture for food and cover. Snakes, bobcats, eagles, and hawks kept the rodents at acceptable levels. Coyotes, deer, possums, armadillos and raccoons use the area at night.
The most important thing we have learned is that considerable grazing can take place even while trees are being established providing it takes place after trees (hardwoods only) have lost their leaves for winter.