By Malinda Geisler, content specialist, Ag Marketing Resource Center, Iowa State University.
Revised April 2008.
Overview
The black walnut tree, also known as the American walnut, is native to North America. According to the National Resources Conservation Service, black walnut thrives in deeper, well-drained, neutral soils. It must have direct sunlight and requires about 35 inches of annual precipitation. The tree usually matures in about 150 years. An average tree will grow to 70 to 80 feet in height and a diameter of two to four feet. In addition to producing nuts, the tree produces wood that is used for furniture veneer.
No USDA statistics are kept on black walnut production. Black walnut hulls need to be removed as soon as the nuts fall from the trees. For small amounts, walnuts can be spread out on a gravel driveway and driven over for about one week. A hand-operated corn sheller can be used to remove walnut hulls. In larger operations, mechanical devices are used. After the hull/husk is removed, the nuts need to be dried for at least two months in a place with good air circulation.
Sources
Black Walnut, Virginia Tech, 2001 - This online document provides a review of the harvesting, processing, marketing and usage of black walnuts.
Walnuts: Second Biggest Nut Crop Produced in the United States, Fruit and Tree Nuts Outlook, ERS, USDA, 2005.
Other Links
- Black Walnut Financial Model (Version 2.0), University of Missouri Center for Agroforestry - This Excel spreadsheet was developed to assist potential growers with decisions on tree spacing, nut harvest and whether to use improved or unimproved trees.
- Black Walnut Plantation Management, Purdue University Cooperative Extension Service, 1994 - This online manual outlines black walnut plantation establishment and management.
- Center for Agroforestry, Universty of Missouri.
- Growing Black Walnut, University of Minnesota Extension Service - This bulletin offers sound research with practical applications for black walnut tree growers.
- Growing Black Walnuts for Nut Production, Center for Agroforestry, University of Missouri.
- Growing & Processing Black Walnuts, Tom Clothier's Garden Walk & Talk - This site offers instructions for harvesting and extracting nutmeats for home consumption.
- Northern Nut Growers Association, Inc. Experts on Black Walnuts - Experts on black walnuts may be located by selecting the black walnut box on this link.
- Nut Production Handbook for Eastern Black Walnuts, USDA Forest Service, 1998.
- Tree Crops for Marginal Farmland-Black Walnuts, Virginia Cooperative Extension, 1998 - This publication describes the most effective practices used to grow black walnuts in the southern United States and the cost of these practices. It includes an economic analysis that uses usual costs and expected returns to determine outcomes of representative investments.
- Walnut, Integrated Pest Management guidelines, University of California, Davis.
- Walnut Council - This association helps build markets for wood products and nut crops.
- Walnut Index, University of California-Davis - This site provides links to other walnut resources.
- The Walnut Tree: Allelopathic Effects and Tolerant Plants, Virginia Cooperative Extension - This online document reviews unique characteristics of black walnut trees.
Links checked February 2008.