Deer browsing and inadequate soil moisture are most often the major constraints to a successful agroforestry planting in Central Wisconsin. Practical methods to address these constraints are being demonstrated on a 2 acre planting established in April 2007 on an abandoned field. The project used agroforestry principles to plan a multi-layered planting of trees, shrubs, and perennial plants that fully uses the light, water, and nutrient resources of the site. Species were planted in a modified alleyway design to demonstrate growth and yield potential for a variety of potential crops in an area of low rainfall, sandy soils, and high deer populations. A unique aspect of the project is the watering system. Natural field runoff is distributed through a system of terraces and supplemented with a drip irrigation system fed by stored barn roof runoff. The project demonstrates a diverse, profitable, and sustainable system that can be replicated at the specialty crop or commercial scale by farmers and forest woodlot owners. The demonstration project is partially funded by the U.S. Department of Agriculture National Agroforestry Center with support from the Golden Sands Resource Conservation and Development Council, Inc.
Agroforestry combines agricultural and forestry practices to create a profitable and sustainable land use system for production of food and fiber. Erosion and water quality impacts are minimized. Tilling is reduced and harvesting is spread over the growing season for a diversity of crops. Presentations at workshops and discussions with the local Resource Conservation and Development Council, Inc. and University of Wisconsin Stevens Point College of Natural Resources staff prompted the landowners to explore the opportunities for an agroforestry planting on their tree farm in Portage County, Wisconsin.
Studies suggest that agroforestry systems can realize substantial per acre profits by capturing niche and/or local markets. Landowners will be able to sell a greater diversity of products over a longer period of time, and at the same time protecting soil, air and water resources. Although there are many resources describing the potential for nut and berry crops (Finn 1999, Josiah & Lackey 2001, Josiah 2001a, Josiah 2001b, Vollmers, C. & E. Streed 1999), estimates of establishment costs and potential yields vary greatly. Based on estimates for several berry crops, establishing the crop may be $2-3000/acre and, once established, profits may be in the range of $1-4,000/acre. Using the system described below, the crop would be planted on approximately 20-30% of an area; therefore costs and profits would be proportional. The objective of this project is to have a diversity of edible crops that also provides wildlife food and cover. The project will help to quantify the costs and potential revenues from such a system.
Goals of this project are to:
- Stimulate the use of sustainable agriculture methods, including: adopting modified alley cropping systems, enhancing windbreaks, utilizing non-irrigated field corners, and using marginal uplands;
- Demonstrate ways to conserve moisture and reduce weed competition, including: terracing seed beds, mulching, and using drip irrigation systems with stored roof runoff and gravity flow;
- Document the survival, growth and yield of potential nut and fruit species for this area; and
- Expand the production of nut and berry crops by traditional farm operations as either small-scale specialty crops or larger-scale operations.
The site is ideal to demonstrate ways to maximize water and light use. Previous attempts to establish an orchard of American Chestnuts failed do to lack of moisture and damage from deer and rodents. The demonstration will especially address the need for adequate site preparation and deer damage control. The 2 acre field is primarily a Rosholt sandy loam soil with 1-6% slope. Runoff from an uphill area is funneled down a swale in the middle of the field, allowing water to be diverted along contours throughout the field. Ten-foot wide terraces were laid out along contour lines with a minimum of 10 feet between terraces. There are 5 planting beds each about 400 ft in length with 6 additional shorter beds for a total of 2,400 linear feet of beds (25% of the area). The alleyways were left in native grass cover.
The planting includes a mix of trees and shrubs arranged to maximize the use of light, water, nutrient and water resources. Nut trees were planted on prepared seed beds with an under story of nut and berry shrubs, with herbaceous perennials included along the edge of the terraces. Each terrace has 2-3 rows of plants arranged according to their individual needs. Trees have about 20-ft spacing with 5-8 foot spacing for shrubs. Tall trees were planted on the uphill / northerly side to reduce shading of the intermediate and shorter shrubs. The arrangement of plants was mapped out on paper and surveyor flags used to locate each plant in the planting beds. Aluminum tags were wired to each tree and shrub with unique identification numbers for record keeping. The plants were inspected approximately two months after planting to determine status and measure diameter and height. A necessary part of the inspection was to correct the planting map to reflect the final location of each plant.
Berry, fruit, and nut plants were selected to demonstrate a variety of potential agroforestry crops for Central Wisconsin. Over 40 species and varieties were planted on the site in the spring of 2007, including 240 trees, 480 shrubs, and 250 perennial plants. Nut trees included white oak, bur oak, shagbark hickory, American chestnut, black walnut, and butternut. Fruit trees included apple, crab apple, cherry, Nanking cherry, apricot, pear, and plum. Berry shrubs included blueberry, lingonberry, June berry, elderberry, buffaloberry, currant, highbush cranberry, raspberry, and blackberry. Hybrid hazel nut shrubs were also included. Herbaceous plants included strawberry, asparagus, rhubarb, and perennial herbs. False indigo plants were scattered throughout the site to promote nitrogen fixation with seeds of lupines, lead plant, and prairie clover planted representing other legumes.
Plants were grouped according to growth requirements; for example: two beds contained the fruit trees and shrubs; herbaceous plants were planted in a low area with heavier soils and more moisture; acid-loving blueberries and lingonberries were planted in a bed with sulfur supplements; black walnuts and butternuts were planted in a separate area to minimize impacts allelopatic effects on other plants; and a small planting of hybrid poplar and willow was established to demonstrate the potential for a high yielding, short rotation crops for either fiber for pulp wood or biomass for energy.
Weeds severely limit the survival and growth of new plantings. Beds were plowed the previous year to reduce weeds. Fabric mulch and over 90 cubic yards of wood chips were used in the beds. Analysis of soil samples showed an average pH of 6.8 (6.4 - 7.4), organic matter content of 1.8% (1.5-2.5%), and relatively good nutrient status. Fertilizer supplements are planned in the future.
Deer browse relentlessly; however, many birds and other wildlife will benefit from the plantings without destroying them. An 8-foot high, 10-strand, high tension solar-powered electric fence was installed to control deer damage with a useful lifespan of up to 20 years for the fence. Tree shelter tubes were used to minimize rodent damage. Raptor control of rodents is also being encouraged by mowing alleyways to reduce cover and by installing a 20-ft raptor perch.
Plants require an inch of rain or gallon of water per week for optimal growth in the sandy-loam soils at the site; however, the mulch reduces this requirement by reducing evapotranspiration and weed competition. The contour beds also provide an efficient way to catch surface runoff. To insure adequate soil moisture during dry periods, water runoff from a nearby barn roof is being stored and used in a drip irrigation system. Gravity flow is used to distribute the water. The water flows to the field in a buried 1 - inch line and then distributed to the plants using 1 inch line with a single emitter supplying 1 gallon per hour to each tree or shrub. In addition, soaker hose is used for plants growing close together.
The water storage capacity requirement is based on climate data from the nearby Hancock Experimental Station for the past 25 years (1971-2004) for the critical April through September growing season. The average total rainfall for these six months is 23 inches or about an inch per week. Monthly average totals for April to September are 2.94, 3.65, 4.30, 4.00, 4.12, 3.56 inches, respectively. There are about 7 rainfalls per month of greater than 0.10 inches. Rainfall events averaged about 0.50 inches (excluding the rains less than 0.10 inches) with a maximum daily rainfall event of 9.43 inches.
Based on the past 10 years (1995-2004), the longest string of dry days (<0.10 inches) during April through September are 22, 24, and 28 days which all occurred in late summer. In May and April there were typically six-seven 7-day periods with no rain, often two-three 10-day dry periods, and sometimes periods of 16-18 dry days. Therefore, it was determined that adequate storage for a 2 week dry period would be required.
Rain water runoff from the barn roof is stored in two 1,100 gallon tanks inside the barn about 500 feet from the site. Gutters collect rainwater from 2,400 square foot of barn roof with the potential to collect over 1,100 gallons of water in a 1-inch rainfall event. The system was designed to capture all rainfall in typical rains but to prevent tank overflow in heavy downpours or when the tank was full. Downspouts from three sections of gutters were directed into a screened gutter manifold and then into the tanks. The tanks were located inside the barn loft to reduce sun damage with additional floor bracing required to support the tanks. The downspouts will be manually redirected to divert the water during the winter.
Currently the irrigation system is under manual control based on rainfall and assessment of soil moisture. There are emitters for 330 plants and soaker hose for another 215 plants. Plants not irrigated include some in low areas that typically have adequate moisture and drought resistant plants such as buffaloberry and false indigo. The system was tested by collecting water in jars located along each of the irrigation lines. It was determined that to maintain uniform distribution, about 200 emitters/soakers is the maximum number to irrigate at one time. This was especially true when the backup well system was used that had more pressure but only a 1 inch hose connecting the well water to the system. Typically, two to three beds are watered for a 2-hour time, as needed.
Irrigation benefits will be demonstrated in the first two planting beds. An identical set of species was planted in each of eight 100-foot sections. Half of the sections are being irrigated with the drip system while plants in the other sections will depended on rainfall and surface runoff.
Harvesting berries will begin in the next few years with nut and fruit crops anticipated in 5 years for dwarf fruit trees and hazels, and 15 years for oaks and hickories. Yields will be measured and compared. Land-owners, neighbors, and friends will benefit from the harvests.
Maintaining the planting will require annual monitoring of plant survival, treating diseases, weeding, mowing the alleyways, pruning, and fertilizing. The measure of success will be the survival and growth rates of the selected species. Detailed growth measurements will be taken the first few years to evaluate potential of the species included.
Based on our initial experience, establishing the agroforestry planting can be a challenging experience. Our initial measure of success is a 90% survival rate for trees and shrubs after two months in an average rainfall year. Ordering plants was a difficult task because nurseries often do not give complete information as to species, seedling size, mature size, etc. Plants were acquired from nine separate sources resulting in mix-ups in species sent and dates received. Mortality from one nursery was twice as high as the other suppliers. Installing the deer fence and irrigation system had a steep learning curve. Perennial grasses and weeds were reduced by seed bed preparation and mulching; however, a full year of tilling and herbicides may be needed to adequately reduce the weeds. The use of tree shelters is problematic. Available tree shelters were used to minimize rodent damage with the expectation that deer damage would be eliminated by the deer fence. However, some mortality has been related to the tubes and concerns related to potential winter damage are well known.
The success of the demonstration project has benefited from the input and support of several institutions and individuals. The project is partially funded by the U.S. Department of Agriculture National Agroforestry Center Grant 68-3A75-6-194 with support from the Golden Sands Resource Conservation and Development Council, Inc. The unique aspects of the project have generated interest resulting in volunteers helping with planting; donations of mulch, tree shelters and plants; and lots of advice.
The proposed project provides many opportunities for demonstrating agroforestry approaches to other landowners, farmers, and natural resource students. Information and technology transfer will occur in a variety of ways, including:
- Lessons-learned report describing design process for other landowners;
- Brochures distributed to site visitors, media, government agencies, etc.;
- Sign at the site explaining the project;
- Outreach through tours and talks;
- Press releases and articles; and
- Utilization of the site by University of Wisconsin Stevens Point classes.
Finn, C. 1999. Temperate Berry Crops. p. 324-334. In: J. Janick (ed.), Perspectives on new crops and new uses. ASHS Press, Alexandria, VA.
Josiah, S. 2001a. Hybrid Hazelnuts: An Agroforestry Opportunity. U. of Nebraska, Lincoln School of Natural Resources Sciences and Cooperative Extension.
Josiah, S. 2001b. Marketing Specialty Forest Products. U. of Nebraska, Lincoln School of Natural Resources Sciences and Cooperative Extension.
Josiah, S. & J. Lackey. 2001. Edible Woody Landscapes for People and Wildlife. U. of Nebraska, Lincoln School of Natural Resources Sciences and Cooperative Extension.
Streed, E. 2000. Minnesota-Grown Opportunities: Hybrid Poplar. Center for Alternative Plant and Animal Products (CAPAP-U of MN). 352 Alderman Hall, St. Paul, MN 55108.
Thomas, Margaret G. and David R. Schumann. 1993. Income Opportunities in Special Forest Products--Self-Help Suggestions for Rural Entrepreneurs. Agriculture Information Bulletin AIB666, U.S. Department of Agriculture, Washington, DC.
Vollmers, C., E. Streed. 1999. Marketing Specialty Forest Products. FO-07278. University of Minnesota Extension Service, St. Paul, MN.