Equipment for Oil Crops

by I. F. REED THE DEVELOPING war situation in 1939-40 indicated that the United States should get in position to produce many of the vegetable oils normally imported, as supplies might be cut off. The program that was started to prepare for such an emergency called for the production of substitute oils to replace coconut oil, olive oil, and others that could not be produced readily in this country.

The need for equipment to handle many of the jobs encountered in producing and harvesting the oil crops soon became evident. Many of the operations were being done by hand methods because of the surplus of labor in the area where they formerly were produced. Under war conditions it was impossible to obtain labor to do the jobs except at prohibitive costs. Efforts of the staff of the Tillage Machinery Laboratory at Auburn, Ala., were directed toward the development of equipment to aid in producing castor beans, peanuts, and tung nuts, which yield oils important in their applications in medicines, foods, paints, and so forth.

The acres in peanuts increased from about 2 million before the war to more than 3 million in 1945 despite the shortage of farm labor and machinery. The increase was made possible by making the use of all available equipment that would reduce man hours required to produce and harvest the crop. Seedbed preparation, planting, and cultivating could be handled effectively with the available equipment. The bottleneck was in harvesting.

Before 1940 most of the peanuts grown in the Southeast were loosened with a plow arrangement and lifted out of the ground, shaken, piled, and stacked by hand; harvesting and picking in that way took about 32 man-hours per acre. Farmers began using tractor-mounted bean harvesters or peanut blades on the cultivators to plow two rows of peanuts loose at a time, after which they were lifted out of the ground and windrowed with heavy-duty side-delivery rakes. In that way the man-hours required for the two operations were reduced from 13 to 1.25. Repair costs were high, vines in the windrows were tangled, and too many peanuts were knocked off the vines, but the rake helped get the job done, and no doubt made possible the increased production despite the reduced manpower on farms.

A tractor-mounted peanut shaker is one of the machines developed especially for harvesting peanuts. With it one man lifts, shakes, and windrows two rows of peanuts that have been loosened by blades on the tractor cultivator frame. The windrow is loose and can be stacked as easily as hand-piled peanuts or, if left, dries out rapidly so that in favorable weather the peanuts can be picked from the windrow in 5 to 8 days. A combine equipped for picking peanuts from the windrow or a picker arranged to do it will do this job in 3 man-hours per acre. As the stacking operation is eliminated, the man-hours required for harvesting an acre of peanuts can be reduced from 32.0 to 3.75.

Several of the USDA-type peanut shakers have been built and have proved effective. Manufacturers are developing other types of shakers.

Peanuts may be planted with or without shelling, but most farmers prefer to plant shelled seed. It is much easier to handle, requires less time and moisture for germination, and usually produces a more uniform stand. Getting seed shelled by hand is tedious and costly and most shelling plants split or otherwise damage a relatively high proportion of the nuts. In either case, the farmer often gets back only 50 to 55 pounds of shelled seed per 100 pounds of unshelled stock, whereas his peanuts may grade 65 to 70 percent sound kernels. This led to the development of a sheller for seed peanuts.

The USDA sheller, as it is called, for seed peanuts is only a little larger than the well-known one-hole hand-operated corn sheller and requires about 1 1/2 horsepower for its operation. It will turn out in 1 hour 300 pounds of shelled nuts, the amount a man can shell by hand in 30 days of 10 hours each. The sheller is simple in its construction, operation, and adjustments. Tests show that seed shelled in this machine and disinfected as recommended to control disease organisms will germinate about as well as hand-shelled seed, even if stored as long as 9 weeks before planting.

Since this country was not in a position to grow enough castor beans to meet its needs, a program to increase the seed supply was started in 1941; in 1942 about 10,000 acres were grown in the lower Mississippi Valley and Texas. A 700,000-acre production program was planned for 1943. However, Mexico and other countries furnishing us castor beans and castor oil joined the Allies. We were assured of a source of supply, so the production program was abandoned.

As countries furnishing castor beans before the war used hand methods for harvesting and hulling, no effective equipment was available. Harvesting was complicated by lack of uniformity in ripening of the seed. Often ripe beans, green beans, and blooms could be found on the same plant, and the early spikes would drop their seed before the later ones were ripe. Some castor beans were harvested experimentally with a modified grain combine, but the method was not considered satisfactory. Observations indicated that plant breeders could in time produce plants adapted to mechanical harvesting.

Although the small acreage of castor-beans grown in this country could be harvested by hand methods, success of even the seed-increase program required development of an effective huller. A huller, developed in 1942 and improved in 1943 and 1944 by the Department at the Tillage Machinery Laboratory, consists of a simple rubber-covered cylinder operating a definite distance from a rubber-covered concave. The beans are fed between these units at a fixed rate and the rubbing, rolling action loosens the hulls. The beans are then cleaned by use of a suction arrangement for removing the loosened hulls and other light material and screens for removing small heavy material. Efforts spent in developing this machine were not wasted, as 20 hullers manufactured and shipped to Mexico and 6 to South America were used in producing castor beans for this country's needs.

In another huller, developed at the University of Tennessee, the hulls are loosened by passing the beans between stationary and rotating rubber-faced plates spaced a definite distance apart. All separation of hulls and dirt from the hulled beans is by means of air. Five hullers of each type described were built and used for hulling the 1942 crop.

The production of tung nuts has increased slowly in the United States since 1932. The production for 1945 was estimated at about 9,000,000 pounds which, however, is less than 10 percent of normal consumption, based on imports from 1935 to 1939.

More than 80 percent of the tung oil used in American industries is utilized by paint and varnish manufacturers, who prefer American oil, because it is generally superior to that produced in China. Tung oil is used also in the linoleum industry, in the manufacture of certain insulating materials, in the electrical industry, as an ingredient in some automobile brake linings, and in other products.

Tung fruit fall from the trees as they ripen over a period of 6 weeks or 2 months. The common practice is to allow them to lie on the ground until dry enough to store without heating, and then to gather by hand and store them in ventilated bins or sheds until dry enough for milling. Much labor is required in both gathering and handling. Equipment is needed to reduce the labor in these operations and the amount of storage space required for handling the crop. The problems thus fall into two phases-gathering and hulling, handling and storage. Attempts have been made to develop gathering equipment. Several projects look promising, however, and tung growers are changing tillage methods in their orchards so as to have the ground surface relatively smooth at harvesttime to enable them to use gathering equipment that might be developed.

The only tung nut hullers heretofore available on the market are adaptations of heavy-duty plate-type grinders. They are not effective when the hulls are relatively wet, which means that the fruit must be stored 4 to 8 weeks before hulling.

The USDA portable tung nut huller perfected in 1945 consists essentially of a perforated basket surrounding a rotor that causes the tung fruit to be broken up and the hulls removed from the nuts. The nuts and hulls fall onto a shaker screen and are carried under a suction nozzle. The action of these units removes all the debris. It will handle wet fruit as gathered in the orchard so that only the nuts have to be stored and these require less than half the space for whole fruit. Since the hull normally contains more moisture than the nuts, it is possible to gather and handle wetter fruit than under the normal arrangement.

The huller is especially effective if used with a drier as the nuts from wet fruit can be readily dried for milling. With the machine, the hulls are removed and scattered in the orchard; that saves handling, hauling, and storage space and leaves them where their fertilizer value may be utilized. Moist fruit can be hulled and the nuts dried rapidly for milling, thus making it possible to start oil mills earlier in the fall. Fruit containing too much moisture to store safely can be hulled, so that gathering crews can start sooner after rains.

Stationary tung nut hullers using the hulling principle developed in the portable unit are being installed at tung oil mills and have proved to be very satisfactory.

THE AUTHOR I. F. Reed is a senior agricultural engineer in the Bureau of Plant Industry, Soils: and Agricultural Engineering.