FIG. 248.—By chipping lightly and with a small-sized hack and by following good woods practice the life of a turpentining operation can be extended several years
TURPENTINE Pine Chipping to Get Highest Yields
Keen competition makes it necessary for the successful turpentine operator to keep down his costs, get the highest possible yield from his long-leaf pine and slash-pine timber, and maintain the vigor of his trees by proper working. Also the approaching shortage of suitable turpentine timber, with the consequent heavier charge for leases, is a powerful argument for avoiding all possible waste.
The first and most obvious step is to eliminate poor-yielding trees or those likely to die or dry face shortly after the cups have been hung. In old-growth timber, stag-topped trees and trees with dead limbs and very thin sapwood are apt to dry face. In young stands, trees crowded on all sides and with poor tops, thin foliage, and no taper should be marked out. Leaning trees and those with very crooked stems should not be worked. Trees less than 9 inches in diameter, 2 feet above the ground, give such small yields that only in times of very high prices is there any money in working them.
These smaller trees lower the average yield of a crop of faces surprisingly. For example, on a tract under lease by the Southern Forest Experiment Station near Starke, Fla., there are 3,330 faces on trees over 7 inches in diameter. These faces yielded 11.6 barrels of spirits for the 1925 season, or at the rate of 34.8 barrels per crop of 10,000 faces. If trees below 9 inches had been excluded the yield would have been 43.5 barrels per crop. The small trees alone yielded at the rate of only 24 barrels per crop. On the basis of average prices for the five-year period 1921-1925, the returns from trees 9 inches and over were $3,156 per crop. Operating costs, including leasing, working, stilling, and overhead, were estimated to be $1,814. The net profit was $1,342. Operating the 7 and 8 inch trees cost $1,619 per crop, the returns were only $1,709, and the net profit but $90. Had 1924 prices prevailed there would have been an actual loss of $76.
Experience indicates that two-face trees should be at least 14 inches in diameter, 2 feet above ground, and three-face trees at least 18 inches.
In general, faces should be on the south rather than the north side and below the heaviest branches. Faces placed above old “cat faces ” or fire scars are apt to dry out and become nonproductive.
In facing trees no wood should be exposed below the point where the tins are inserted, because fires can not readily ignite faces with no exposed wood close to the ground. The tins should be no further from the ground than is actually necessary for placing the cup. The oblong cup is not so deep as other kinds and permits the tins to be placed lower. Tins should be inserted lightly, so as not to interfere with the circulation of the sap behind the face.
Faces should be so placed that at least 4 inches of uncut bark will always remain between them. Where only one face is put on a tree not more than a third of the bark should be cut away. Though wider faces may yield more for a year or two they do not keep up high yield, and are not best over a long period. Tests have resulted in exactly the same rate of yield from narrow faces and from faces twice as wide, by the middle of the fourth working season. Meanwhile other trees with two faces aggregating a total width three times as great as the narrow ones were actually yielding less than the narrow faces because of the large percentage of the trees unproductive or dead as a result of overwork.
Sharp tools are essential. Dull ones are reputed to bruise the resin duct cells, causing gum to stop running sooner than it otherwise would, although no records bearing on this point have been kept. For best results the edge or shoulder of the face should be kept even and regular. The angle of the peak should not be very sharp since a long peak has a tendency to dry out. But a moderate slope to the streak makes a cleaner cut possible, with the same effect on yield as the use of sharp hacks and pullers.
A strong opinion prevails among operators that a first or “advance ” streak should be made at the time the cups are hung, following which four to six weeks should elapse before the regular weekly chipping starts. Thenceforth regularity of work is insisted upon by the best operators.
The season of work depends, of course, upon the weather. If the best trees give only small yields in the cool weather at the beginning and end of the season, the little trees will fail t® do even fairly well at such times. Therefore, the wise operator will, so far as possible, start chipping in his drifts of large trees, and will continue working them later in the fall than drifts of small timber. The small trees should be handled on a short season, when the weather is most favorable for heavy gum production.
In the light of present knowledge weekly chipping seems most satisfactory. Fortnightly streaks, at half the chipping cost, netted 70 per cent as much gum as weekly work in one of the Southern Forest Experiment Station tests. However, a rough comparison of costs showed less profit for the fortnightly chipping, since chipping costs, in which the largest saving was made, are only a small part of the total cost. Twice-a-week chipping of virgin long-leaf pine in Mississippi some few years ago proved unsatisfactory because so many trees died during the second year as to offset the large yield of the first year.
Experience with various styles of chipping shows conclusively that it is unnecessary to take off more than half an inch of wood up the tree at each chipping; even less than this is recommended on the basis of experiments under way since 1923. When the width of streak was not over three-eighths of an inch the yield over a four- year period was greater than when it was three-quarters of an inch. The advantage of being able to work the face for a longer period is obvious.
The use of small hacks and pullers is increasing among successful operators, because this automatically limits the amount of wood cut away. With small tools a face can be worked for one or two years longer than with large tools. A No. 0 hack and a No. 1 puller are large enough except where the bark is extremely thick. An open-throated small hack is now on the market that does away with the objection, sometimes raised, that No. 0 hacks choke up badly. This modified hack has all the advantages of the regular No. 0 hack and plenty of room for chips and bark to fall through without choking.
The wise operator will vary the depth of chipping according to the character of the timber. %'oung long-leaf pine may stand chipping up to 1 inch deep without serious injury, but the yield is not what it should be during the third and fourth years. Young slash pine, if not too crowded, will stand three-quarters of an inch without much dry face, at least in wet seasons. Old thin sap trees require very light work, and crowded young slash is very susceptible to injury from deep chipping. All timber should be chipped lightly during periods of drought. One-half inch for slash pine and five-eighths for long-leaf pine are conservative depths, if faces are to be worked over a four or five year period.
In scraping it is advisable to avoid taking off wood with the scrape, as this has a tendency to dry face the less vigorous trees.
Deep cuts for inserting tins when cups are raised often result in dry facing. The use of saw-tooth aprons is suggested, since they will hold solidly even when the cut is very shallow.