In 1999, Larry Harper received a grant from the North Central Sustainable Agriculture Research and Education program in cooperation with researchers from the University of Missouri Center for Agroforestry. The primary objective of the project was to determine the amount and type of damage that cattle would inflict on a black walnut plantation. Two secondary objectives were whether soil compaction would be an issue and to demonstrate the potential profitability of a silvopastoral practice when compared with production of hay between the tree rows.
The demonstration took place at HarperHill Farms located near Butler. The site selected for the demonstration was 15 acres, with trees from 12 to 15 years of age. The trees were planted 40 feet between the rows and 20 feet between the trees within the rows. Nearly all are grafted to improved varieties. However, a few trees had not been grafted in order to compare production characteristics. All trees received 60 pounds of nitrogen in the form of ammonium nitrate in April of each year prior to grazing.
In April of 1999 and 2000, 25 steer calves weighing an average of 585 pounds were purchased and placed on the grass. The acreage had been divided into paddocks of 1 to 2 acres, using single-strand electric polywire, which could be moved by rolling it on reels so that only a limited amount of fencing was necessary. The electric fence was powered by a low-impedance charger commonly referred to as the New Zealand system of electric fencing. All 25 steers grazed a single paddock for about one day and then rotated to the next paddock. With 18 paddocks, they would be grazing each paddock every 18 to 24 days, depending on the forage regrowth. The management-intensive grazing system was chosen for its potential of reducing animal traffic and exposure of trees to damage as well as its other potential benefits to both trees and forage.
Steers were short-grazed for only 100 days and sold the first week of August. They received only forage, salt and mineral. A pour-on treatment was applied before they entered the grazing system to discourage external parasites and corresponding tree rubbing. Flies were controlled with insecticide ear tags.
In the third year of the study, 2001, the forage between the rows was harvested for hay and sold to compare profitability of grazing versus harvesting. The forage between the tree rows consisted mostly of smooth bromegrass with some legumes.
The results are in! At most, it was found that the grazed trees may have diameter growth suppressed by only 20 percent to 25 percent. It appears that in a management-intensive grazing practice, height growth is not affected by cattle grazing. Miscellaneous physical damage to trees was noted. A few trees (seven out of 116) were killed by the cattle. All were less than 4 feet tall when the cattle entered the grazing area. The most prevalent cause of damage was rubbing, especially to alleviate the effects of face flies. Cattle browsed branches from the trees, which seemed to be more mischief than hunger. This browsing did cause damage by ripping off strips of bark with the small branches, although most of the wounds have healed. An overall browse line was noted at about the 5-foot height.
From these observations, it can be concluded that trees must be 10 to 12 feet tall and have a diameter of at least 3 inches if they are to be safely grazed with cattle of this size. To overcome the browsing effects and stripping of bark, it might be wise to prune the trees to at least the 5-foot height. That would leave half or more of the crown in place as is generally recommended by most foresters. Other trials have shown that when a single strand of electric polywire is placed 4 feet on either side of the tree row, grazing can begin immediately after planting. Cost of the electric fencing is reasonable, especially when rolled on reels and moved with the cattle from paddock to paddock.
In terms of profitability, cattle will be more profitable than selling the hay crop, in most years. During the two years of experience with this project, HarperHill Farms recorded a gross profit per steer of between $50 and $75.
Since less than 1 acre (.84 acre) was required per steer for the grazing season, this figure can be translated into a $60 to $89 gross profit per acre. This profit figure does not include costs of land, labor or fertilizer. Land and fertilizer costs are charged to the primary enterprise of growing trees for nuts. Labor was not charged because the same labor used for 25 steers could suffice for a herd of 100 (even 300) head under a management-intensive grazing system.
Short-grazing steers can be a most complimentary enterprise with a black walnut or other nut production agroforestry system. By removing the cattle the first of August, the grass has ample time to recover before nut harvest in September. The manure has time to dry and disappear so it will not affect nut quality. And, the cattle price trends for the past 20 years show that selling 750- to 800-pound steers the first week of August avoids a traditional late summer price slump. It also is advantageous because the cattle are not carried through the August gain slump, or even reversal. Plus, at $12 per acre (continued on page 5) per mowing, there is a considerable contribution to the bottom line.
In 2001, the forage was baled for hay and sold. The hay yielded 2 tons per acre. Half the hay was given to the custom hay operator to pay for harvesting. The other half was sold for $45 per ton. This was a gross profit of $45 per acre without land or fertilizer charges.
This research demonstrates that it is practical to combine steer grazing with a black walnut agroforestry practice. Potential damage to the trees by the animals can be overcome by management techniques. Slight decreases in growth of the trees are more than offset by the income potential of the cattle operation, especially in the early years when there is no income from the nut crop. Hay can be harvested during years when cattle aren't the most profitable option.
For more information on this study, contact Larry Harper at HarperHill Farms, Inc., 908 Danforth Dr., Columbia, MO 65201; (573) 442-5326; or e-mail: lharper@tranquility.net
Cattle graze between rows of walnut trees at HarperHill Farm in Butler. Larry Harper just completed a two-year study on the feasibility of grazing cows in walnut plantings.