A beautiful black walnut tree
Agroforestry is playing a role in the early days of a new black walnut industry developing in western Oregon. Among the first private landowners who have planted black walnut on their farms for timber are several
innovators experimenting with intercropping as a means of improving the growth and economics of the tree crop. Those involved in the new industry are optimistic that the Northwest can develop a market niche based on the unique properties of their home-grown black walnut. The oldest business in Oregon specializing in walnut wood is Goby Walnut Products. The business was started in 1975 by Gary Goby, who is also President of the Oregon Chapter of the national Walnut Council.
Agroforestry Trials:
A member of the Oregon Chapter, Peter Kenagy, is experimenting with a variety of trees, forages and crops for interplanting in black walnut plantations on his 420 acre Willamette Valley farm. In one of his first plantings of black walnut four years ago, Kenagy interplanted a wildlife forage mix between rows of trees planted at 10 X 20 ft. spacing. The 10 ft. wide forage
Lines up on the black walnut trees.
strips, which include sorghum, sudan grass, buckwheat and sunflower, are intended to attract birds and other wildlife. Plastic tree guards (political signs creatively recycled) protect the walnut trees both from herbicides sprayed along the tree row to reduce moisture competition, and also against rodent damage. Kenagy plans to maintain the wildlife forage for 6 to 7 years until the trees achieve canopy closure.
In a recently cleared area, Peter Kenagy has tried intercropping black walnut with sweet corn. He planted pregerminated nuts in rows 20 ft apart, sprayed once for weed control, and then drilled corn seed between the tree rows. The same traveling boom spray gun was used to irrigate the walnut/corn trial as for crops in the adjacent fields. Kenagy said that the corn produced about the same yield as in his other fields and provided the economic justification for irrigating the new black walnut plantation.
Kenagy is also testing several fast-growing, short-rotation tree crops for interplanting with black walnut. Hybrid poplar and paulownia act as a nurse crop to force straighter growth of the black walnut and also provide a source of income early in the walnut rotation. Poplar has proved to be too competitive when planted at the same time as walnut in Kenagy’s trials, so he now plans to plant black walnut at double the final density two or three years prior to planting poplar or paulownia.
Another Northwest innovator is J.T. Lowe who intercrops black walnut with Douglas fir that are managed for Christmas trees on his farm near Portland. The firs are planted at 5 X 5 ft. spacing, within walnuts planted at 15 X 15 ft. spacing, and harvested for Christmas trees at after 7 years. However, in older stands of healthy walnuts, Gary Goby has seen evidence of juglone induced growth inhibition of young interplanted fir trees when their roots intertwine with the black walnut.
Fir trees are growing on the crops.
