The planting was made in 1989. He planted black walnut and green ash in rows 12 feet apart and 12 feet within the row. The walnuts were planted solid in every third row. He put herbicide on the rows during the first three years and a couple more times since then. The trees (all of them) have grown well as the soil is deep and well drained. The walnuts are now about 15 feet tall and average about 4 inches in diameter. The ash are slightly larger and are beginning to shade each other and the walnut rows.
He would like to remove the ash trees and save as many walnuts as possible for nut production and eventual timber production. He is considering using the alleys between the rows for hay production and maybe even grazing eventually.
The alternative is to re-bid the field into the CRP for another seven years for about $60 an acre.
This farm has been in the family for four generations and most likely will stay in the family for another generation or two. He asks what I would suggest.
Committing yourself to an agroforestry system, even one
with immediate cash flow such as from hay or grazing,
requires long-range planning. Economics are a major part of
that planning, of course, but some personal plans must be
made, too. For instance, how old are you? That may seem an
impertinent question, but with a long-term investment some
thought must be given to who will continue to take care of
the trees, at least until they reach an age that they have
market value as a nut-producing plantation or as timber.
In this case the decision is easier because of the continuity provided by the intention to keep the farm within the family for at least another generation or two.
Assuming that the decision has been made to make the conversion to an agroforestry system with black walnut nut production, forage between the rows and eventual salvage of the mature trees as timber, we can make some observations.
The first is: if you are going to do it, do it now.
You have nearly 300 stems growing per acre and you need to remove nearly 250 of them. The job won't get any easier the longer you wait. One of the standards that has been established over the years is that 50 trees per acre in a 40- by 20-foot configuration is sustainable for up to 25 years. They will then have to be thinned to about 25 trees per acre because they will begin to crowd each other and nut production will be diminished.
With the 12 by 12-foot spacing and walnuts every third row, you have the potential for an initial 36- by 24-foot spacing which will give you right at 50 trees per acre. At or before the 25th year, you will remove half the trees for a 36- by 48-foot pattern.
The first thing to do is eliminate the ash. Chainsawing is a possibility. So is a hydraulic shear on the front of a Bobcat or a shearing blade on a dozer or tractor. A critical part of this operation is treating the stumps with herbicide (Tordon RTU) or disking the ground to make sure the stumps do not resprout. Disking may be necessary anyway because grass and legumes likely will need to be overseeded. Orchardgrass, lespedeza and red clover are preferred. If fescue was originally seeded in the field, it may be necessary to kill it with Roundup and reseed with a more desirable mixture. Fescue is not compatible with black walnut trees.
The next move is to go through each walnut row and pick out
the best trees. Selection will be done on the merits of
growth and stem form or straightness. You are looking for a
good tree that will grow a good top for nut production and
have the potential of making a quality lumber log, even a
veneer log. If you have to skip a tree in sequence to get
the best tree, do it. Fast growing, healthy trees are more
important than perfect geometry in the plantation.
Cut the cull walnut trees with a chainsaw and treat the
stumps with Tordon RTU. Now you have the makings of a black
walnut nut production plantation. But not quite.
Native black walnut trees grown from randomly selected seeds will not come into nut production early enough to be economically practical in most cases. Some native trees produce almost no nuts. Nut quality also is questionable.
So, the next step is to assure the production of the quantity and quality of nuts that will make the whole effort financially worthwhile. That means grafting each of the 50 trees per acre (350 total) to a variety of known nut production value. These varieties or cultivars have the potential of producing 2,000 pounds or more of nuts per acre (under top management) when the trees reach maturity or about 30 years of age. They also have high percentages of kernels, up to 35%, which makes them more valuable to the processor.
During the first three weeks of May next year, it will be necessary to graft the remaining trees. It is possible for one person to graft up to 350 trees during the three-week grafting season, but it may be necessary to hire or beg some help from experienced grafters. The varieties to be grafted could be the three most recommended by the Missouri Nut Growers Association (Sparrow, Emma-K, Kwik-Krop). These could be grafted on two acres each, leaving one acre for experimentation with at least a dozen other cultivars that are less proven.
Grafts should be made as high as possible, especially if area is to be grazed. Eventually, over a period of years, the tree would be pruned up to a 9-foot clear trunk to accommodate machinery and to provide a more valuable sawlog or veneer log. From that point, a full crown is necessary to promote good nut production. There is some concern that grafting these larger trees will result in flawed logs which would keep them from becoming veneer quality. One possibility is to graft at the 9-foot height which requires working from a ladder.
Follow up the next spring, and every spring thereafter, with a herbicide band (Roundup and Princep) 4 feet wide on each side of the row or a sprayed circle with a 4-foot radius. Fertilize the field for top hay production according to regular soil tests. Splitting the applications between April and August 1 may benefit the trees the most.
Fertility recommendations likely will change once the trees begin to bear commercial crops of nuts which should be in about six years.
- Larry Harper