Agroforestry has been an interest of mine for many years. Just what is agroforestry? It is the combining of trees and crops or livestock on the same area. The trees can be for timber production, nut production, or fruit production.
Timber production alone is difficult to justify economically, due to the long rotations involved. By using a type of agroforestry, the understory crop can produce income early in the rotation, with the trees providing income at the end of their rotational age.
As with any agricultural system, there are pros and cons to the system. As trees grow, the ground shade increases, which can reduce the yield on some crops. Additionally, the trees themselves can interfere with equipment use unless the spacing between rows is carefully decided at the beginning of the rotation.
Choosing your potential end market for the trees is important as well. Veneer black walnut logs, pulpwood, sawlogs, or simply fruit and nut production are all potential final uses for the trees. Many current crops are sensitive to shade, so as the trees grow, yields drop. In many cases, the final use after canopy closure is some form of grazing or silvopasture.
Black walnut has been used in many studies of the potential for agroforestry. However, do you grow for veneer logs or nuts? The best veneer log trees are not necessarily great nut producers, and high nut production trees generally don’t have the tall straight shape you need for a good log.
At the Kerr Center we have two agroforestry plantings, both used for silvopasture, as well as a grazed native pecan grove. The two agroforestry plantings are different in that one uses pine trees and the other is strictly hardwood.
The Between the Lakes Agroforestry Project is planted to pine trees. The trees are planted on contour. We thinned the planting several years ago. The trees were planted in single rows, and as a result the trees had many lower limbs. This resulted in many trees going to pulpwood and short logs, which are lower value products.
The harvest resulted in many tops and limbs between the rows, requiring me to hire a dozer to push the brush up so we could continue grazing the area. It was essentially a break-even cut. I would now recommend planting triple rows of pine trees, allowing the outer rows to be harvested for pulp around 12-15 years. The remaining trees would be saw logs.
The Bottomland Agroforestry Project is planted to willow oak, pin oak and green ash. Most of these trees would go to pulp wood or pallet wood.
I would not plant green ash again. When the trees were old enough to produce seed, we began to fight seedling green ash everywhere. As a grazing pasture it is great. The livestock love the shade and graze that particular pasture more evenly than any other field in the rotation.
The lesson to be learned is that agroforestry requires long-term planning. You should carefully select the trees, determine the spacing, and evaluate all long-term income streams, and manage accordingly. Agroforestry has great potential, but requires careful management from the beginning to the end of the rotation.