Historic, archived document

Do not assume content reflects current scientific knowledge, policies, or practices.

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N MANY FARMS there are small tracts on

which only brush or inferior timber is grow-

ing which would be more productive if cleared and

devoted to the growing of cultivated crops. Also

many cultivated fields still contain large stumps

which impede farm operations and add to the cost. of crop production.

The removal of brush, trees, and stumps and the preparation of the ground for crops are at best laborious tasks, but the labor in many cases can be greatly reduced if proper tools and methods are employed. The method which succeeds best under one set of conditions may be wholly unsuited to other conditions. This bulletin describes the meth- ods followed in different localities and points out the conditions under. which their use is warranted. It does not attempt to advocate one method as superior to any other, for each has been found satisfactory under the conditions to which it is adapted.

This bulletin supersedes Farmers’ Bulletin 974.

Issued May, 1927

Washington, D. C. Revised June, 1929 Slightly revised February, 1933

ae - 1


By GEorGE R. Boyp, Engineer Assistant to Chief of Bureau, Bureau of Agri- cultural Engineering


Page Page IntPoduculon- aceeeses. ae oe 1.) Stump removal.o2es-5.5- see es. 13 Need for clearing Jland______-__--__~_ ae Grupbing je a-= ee eee sec ous 13 Disposal of the brush____________-~~-- 3 Burming 2s shes lee sese sae 14 Grazing oso eee 3 UW i a pee ee 19 Cutting and burning--_________- 5 Blasting {223252 See esos ces 26 PiOW Me 22 eee ae eee 11 VCC nese ea hy ete 26 Disposal of the stump______~______ 29 Selection of land clearing method___. 33


S FAR BACK as history goes some part of the world’s popu-

lation has been engaged in clearing up new land and putting it into cultivation. It has been said that it takes three generations to make a self-sustaining farm out of cut-over land. Moreover, cleared lands are sometimes abandoned, and must be recleared when again needed for crop production; so that land clearing is a problem in our oldest farming regions as well as in the newest settlements. The stumps left by the original or virgin growth still remain in many sections, and the stumps of the second and even third growth make the land-clearing problem a continuing one in almost all agricul- tural regions. Clearing up land for the plow is a matter requiring hard work, patience, experience, and usually the expenditure of a considerable amount of money.

It is impossible to give any figures of value as to the comparative cost of removing stumps by the various methods described, or any figures of the average or usual cost of stump removal. There are so many different things which affect the cost of stump removal, that costs vary between wide limits. Even when the comparison is made with the stump as the unit, rather than the acre, so many variations are encountered as to render the comparative figures valueless for other lands, or for the same lands at other times. It has been thought that the volume of wood removed would be a good basis of comparison but experiments show that there is so much variation in root shapes and holding power, even among stumps of the same size and species, that the comparative figures are almost valueless. Furthermore, any cost figures are apt to be grossly misleading for the reason that the most profitable kind of land clearing is that which is done with farm labor and equipment at odd times when no other productive work can be done, and the value of this labor is



hard to determine. In general the value of anything is what it will bring upon the market at the time it is available. Generally, the labor and equipment used in crop production on the farm are avail- able for land clearing for only short periods, possibly a few hours at odd intervals, and there is very little outside demand or market for such intermittent labor. It is unfair to charge the land-clearing operation with $1 per hour for the use of a tractor when the tractor is used only for short periods when there is nothing else for it to do on the farm and when it would otherwisc be idle. The same reasoning applies to the use of labor, whether it be that of the owner himself, or labor hired by the month or day.


It is axiomatic that no farmer, either landlord or tenant, can make all the money he should make until he gets his fields in the best possible condition to produce crops at a low cost. No one who has held the handles of a plow in a stump field will deny that the


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I's. 1.—The cultivation of such land is expensive

cultivation of a crop among stumps is an expensive undertaking. A stump and its roots cause a great deal of lost time and broken equipment, occupy valuable space which should be yielding profitable crops instead of producing weeds to foul the entire field, and har- boring injurious Insects. Raising a crop on lands such as shown in Figure 1 is very cxpensive on account of the area lost to production and the high cost of cultivating the crop. Experiments carried on in Georgia show that, under the same conditions, it takes as long to plow 7 acres of stump field as it does to plow 9 acres of clearcd land, so that the cost of plowing stump land is about one-fourth more than the cost of plowing cleared land. Fourteen plow points were found in and around the roots of a lightwood stump in Mississippi. These plow points cost about $1 each, and the stump was blasted out at a cost of 30 cents. Under favorable conditions a field can be more cheaply cultivated by plowing two rows at a time instead of one, and motor-drawn implements do economical work, but the most enthusiastic advocate of these modern, cost-saving, devices has never called a stump field a favorable condition for their operation.


There is a surprisingly large number of farmers in cfit-over areas who have little or no chance to make money farming. These farmers are not confined to any one section or to any group of States. They should be interested in clearing land; in fact, they must clear land before their farms can become profitable, for until'a farm is largely self-sustaining it can not be profitable. Until the farmer has the minimum acreage of cleared land necessary for his particular farm, he must bend every energy toward increasing his cleared acres so that his farm will become a self-sustaining, economical unit.

Although the disadvantages pertaining to the stump field and to the underdeveloped farm are always present, they are especially disastrous during hard times” when the prices of farm products are low. At such times it is necessary, in order to make a profit, that every cultivated acre, and the farm as a whole, be in a condition to produce the largest possible crop at small cost. Clearing opera- tions take considerable time for their completion, so that the land- owner can not wait until a time of high prices arrives in order to get his land in shape to produce a maximum crop to sell at a high price. It follows, then, that land-clearing work, during times ‘of depression, should be carried forward to completion as rapidly as can be done economically.

On most farms there are too many days when no productive labor is possible, and this is particularly true on underdeveloped and under- stocked farms. Wherever such a condition exists, land clearing gives employment for labor which would otherwise be lost, for it can be economically and effectively done at odd times during intervals when farm labor is not required for crop production. "The landowner does not have to wait until he sells his farm to obtain a valuable return from this labor, as he will receive a yearly return in increased crops and in decreased cost of production.

Farmers will realize, of course, that there is some land which should not be cleared, because it will be more profitable if used for other purposes than agriculture.


The first step in the preparation of cut-over land for cultivation is the removal of the fallen logs and brush. The fallen logs may be piled and burned, or they may ; be hauled off, while the undergr owth may be disposed of by grazing, by cutting and bur ning, or by plowing under. The principal factor in determining which method should be used is the length of time the owner is willing to wait before putting the land in cultivation.


Grazing is theoretically an economical way to clear land of brush, ‘and undoubtedly close grazing has a great effect in reducing the cost of removing the stumps at the end of the pasturing period. Goats, sheep, and cattle are the animals most frequently used for this pur- pose. Goats are natural browsers, aud there is no vegetation they will eat in preference to leaves and twigs, but in practice it has been found better to pasture cattle on the tract to eat up the grass, if it has been seeded, before turning the goats into it. Sheep are the next best browsers, but must be more closely pastured than


goats so that they will be forced to eat the bushes. In the cut-over lands of the upper peninsula of Michigan one ewe and one lamb will thrive on 1 acre of cut-over land during the open months and will keep down most of the sprouts. With either sheep or goats on large areas it 1s necessary to fence the land into small sections, con- centrating the animals on each section for a short time until it has been browsed clean, then moving them to another section, then back to the first one, and so on. |

Where grazing is depended upon to remove the underbrush it is usually necessary to cut such of the brush as is too high for the ani- mals to reach. Such work should be done as early in the stage of the operation as possible. The cut brush and trees may be piled with the fallen logs and burned, or they may be left to decay, but when this is done they should be left as they fall and not piled up, as brush in piles generally does not rot as readily as when scattered on the ground. A growth of grass aids greatly in keeping down the suckers and sprouts and hastens the decay of fallen brush, but affords more feed for the stock, so that the standing brush is not eaten so quickly. It is advisable to go over the land at frequent intervals and cut down the growth which may be avoided or neglected by the stock in grazing.

The following method of pasturing is followed with considerable success in southeastern Missouri: In the summer or early fall all of the small trees, brush, and undergrowth are cut down and left where they fall. In December a 4-part mixture of grass seed, made up of timothy, orchard grass, red top, and alsike, is sown by hand. The next spring, after the grass has a good start, cattle are turned into the field. One acre will furnish pasture for two head of cattle, but for short periods or in exceptional seasons five head per acre can be pastured. The remaining timber is cut at convenient times, the merchantable timber and firewood hauled off, and the remainder left to decay. The cattle in feeding will break down the dead tops and the thickly growing grasses hasten the decay of all of the wood on the ground as well as of the stumps. In the early fall of the fourth year the cattle are taken out of the field and the grass is allowed to grow as high as it will before frost. In the winter, after frost has killed the grass, and during a dry time, the grass is set on fire. This fire is usually hot enough to burn completely all of the brush and down logs and partially consume the stumps. The stumps are then removed and the field is ready for plowing.

The pasturing of cut-over lands not only keeps the brush down but it reduces very materially the cost of stump removal. The trampling of the earth around the stumps as the cattle graze about them com- pacts and solidifies the soil and seems to work it away from the lat- eral roots of the stump, so that where land has been heavily pastured for some years the lateral-rooted stumps appear to be sitting on top © of the ground. The 18-acre field of the experiment station farm at Chatham, Mich., which was originally cut-over land, was burned over, then seeded to grass and heavily pastured with sheep for seven years, and finally cleared of stumps and prepared for plowing at .a cost of $19.98 per acre, while an adjoining tract of land, similar in all respects to the 18-acre field except that it was never burned, seeded, or pastured, was prepared for plowing at the same time as


the first field at a cost of from $115 to $125 per acre. This large saving is due in part to the burning and in part to the seeding and pasturing.

_ The practical advantages of pasturing with the main purpose of removing the brush are somewhat questionable. It requires that a considerable sum be invested in stock, and this investment is sub-: ject to all the ordinary vicissitudes of the livestock business with its possibilities of loss as well as of gain, and it is necessary in order that the brush shall be consumed to underfeed the stock, which in- creases the risk of losing on them. Considered as a'means of keep- ing down the brush and also making easier the stump removal, seed- ing and modcrately heavy pasturing is to be recommended when it is not required to cultivate the land for some three or four years.


The most common method of brush disposal is to cut, pile, and burn it. This method gets rid of the brush quickly, so that it will

Fic, 2.—A log pile should be conrpact and narrow. with the logs lying parallel and should be of good height

not interfere with the immediate cultivation of the land. Down logs, dead tops, and unmerchantable timber are worked up and removed or piled and burned as a part of the brushing operation.

It is a common belief that brush cut in the summer or early fall is not apt to sprout again, but investigations have demonstrated that there will always be some second and even third growth, regard- less of when the brush is cut. To insure killing the growth it is necessary generally to go over the field at intervals and cut down the new growth. A good deal of brush is cut in the winter, because other farm work is not so pressing at that time and more labor js available.

The tools needed are few, but they should be in good working order. An ax, a brush scythe, or bush hook are about all that is needed for cutting the brush. For handling the logs a team, a chain about 15 feet long, a 30-foot length of one-half inch cable, and a crosscut saw are required.

The best piles of brush and logs are high and rather narrow, as shown in Figure 2. Piling in small piles, fairly high, with the logs


lying parallel is cheaper and better than making large piles, since the latter require additional labor and if the pile is too large, the fire may become so intense as to injure the fertility of the underlying soil. Logs and stumps should be burned in separate piles, as much more compact piles can be made in this way. In piling logs which can not be readily handled, a team, cable, and two timber skids may be used to advantage. The pile is started by passing a cable end under the log to be moved and hooking it to the log which is to be the center piece of the pile; the team, hitched to the other end of the cable, rolls the log up to the pile by means of this rolling hitch. It is good practice to put two or more crosspieces under log piles to provide air circulation when the pile is drying out and a draft when it is burning. Sometimes the brush is piled in wind- rows, which saves moving it through any considerable distance, but the windrows do not always burn up completely. Such windrows should extend in the direction of the prevailing wind in order to get a good burn. Very large logs are most easily burned in place after splitting their ends with explosives.

As a rule standing trees should be cut down before the brush is cut. It is generally better, especially where the trees are thick, to cut the trees and later remove the stump than it is to remove both tree and stump in one operation. Although it is somewhat easier to

Fic. 3.—Splitting gun

pull a tree with a stump puller than it is to pull the green stump on account of the greater leverage which may be obtained by fastening the pulling cable higher on the tree than is possible on the stump, and though it takes but little more explosive to blast a tree than a green stump, in thick woods the fallen trees occupy so much ground space as to greatly increase the difficulty and cost of the operation. |

In this brushing operation, any wood which is valuable for fire- wood or other use, should be removed from the field. In splitting logs a splitting gun can be used to good advantage, especially for the large logs of the West. It consists of a pointed steel cylinder, hollow for half of its leneth, about 114 inches in diameter and 18 inches long. Figure 3 is a detailed drawing of this patented device. A small charge of black powder is loaded into the pointed end of the eun, the latter is driven into the end of the log, and the powder ignited. A very smal] charge of powder will split a large log into ce which can be easily handled by one man. The gun should be

riven into the center of the log, or into solid wood, and knots, rotten spots, and cracks should be avoided. The same results may be ob-

1 See ‘“ Measuring and Marketing Farm Timber,” Farmers’ Bul. 1210, U. S. Dept. Agr., also Utilizing Poles and Timber in Farm Building,’ Ext. Bul. 24, Mich. Agr. Col., East Lansing, Mich.


tained by placing a small charge of explosive in a hole bored in the end of the log, tamping the charge in place and firing it.

In some of the hardwood sections of the South the general custom is to cut and burn the brush, deaden the trees, and put the land in cultivation, allowing the deadened trees to remain until they become so weakened by decay that they are blown down, and later are piled and burned. The stump is not removed until it becomes so rotten _ that it can be easily grubbed out. As it may take anywhere from

6 to 10 years for the stump to decay, and as the farming operations during all of this time are carried on under great difficulties, it is doubtful whether this method is truly economical, although it requires less expenditure of labor and money than would be the case if the trees were removed. Unless the dead standing trunks can be burned in place, as is sometimes done, it costs almost as much to remove them after they decay and fall as when they are green. Leaving the deadened trunk in place will not hasten the decay of the stump or make its removal cheaper.

Burning standing and live brush is of great value in destroying © the brush and also in reducing the cost of stump removal. Fire in a cut-over country is always dangerous, and such a fire should be started only after complete and detailed arrangements for con- trolling it have been made. In many States it is necessary to pro- cure a permit from the local authorities before a woods fire can be started, and there are certain seasons when such permits can not be obtained. A large percentage of the devastating forest fires in cut-over sections originate in land-clearing fires, so that the necessity for great care and watchfulness and of strict compliance with the law should .be appreciated by everyone.

Tables 1, 2, and 3 give the comparative amounts of work required

er acre in brushing, piling, and burning on two tracts of land in

innesota, one having been burned over and the other unburned, also the labor required to remove the brush and the explosives required for blasting the stumps.’

TaBLeE 1—wWork required per acre for brushing, piling, and burning brush on burned and unburned land in Minnesota

Saving in Operation Green timber Burned timber er ae


Man Horse Man Horse hours hours hours hours Per cent PUG obec es eee ee oa ee eee Odeo obo S eee BO, Pebe eau 40

Felling, trimming timber____.-.._..--..------------- 80.5 |... _-_ Os Na cleus 2 16.1 Burning brush-______- peti aa dais tial oe ianre aie ed aaah Oi) eis ia eae ee ee 41.4 Miscellaneous operations, skidding logs, poles, etc__- 65 37.5 35. 6 37.8 45.2 PE OUR ibe) ost cy Set oe Neco eZ tS So 218. 7 37.5 155. 1 Sle Bhusc tee,

2From Bul, 220, Agr. Exp. Sta., Univ. of Minn., ‘‘ The Effects of Forest Fires on Land Clearing and Crop Production.”



TABLE 2.—Comparative labor units per acre required in disposing of stumps in Minnesota

Item Green unburned; Green burned | Dry unburned Dry burned

mn | rr re |

Man | Horse | Man ! Horse | Man | Horse | Man | Horse hours | hours | hours | hours | hours | hours | hours | hours

(BIGSUING ceccscye econ ossceseeoeeek ase 30.8 |... TOR Nea het Te Noes ace 2s Ds AM sepals ce Piling refuse material__.._.._._.__.__- 13) escoueee 5. 2 6.3 14, 4 28. 8 1.7 1.9 Pulling, piling small stumps_-___.___- OF. ees 25.9 25. 8 17.4 34.8 22.1 21.8 Pulling, piling after blasting..________ - 35 69. 5 22. 2 22. 6 44,3 88. 5 18 16. 7 Burning..._.-.---------- Apustesecsne. 8:6 \sncecese Bed \eureces DD tices DEO ex occ

WOU AN cit re ete hea Ley a ane 82. 4 69. 5 63.3 54.7 85.3 | 152.1 47 40. 4

TABLE 3.—Eaplosives and materials used per acre in blasting out the stumps in

Minnesota Green Green Dry Dry Item unburned! burned |unburned| burned area area area area Dynamite, pounds._...__.----_------------------ eee - ee 171 62. 9 41 14.4 Caps, NUDGE: 2 cee. s ol Cosco hee ee a eee 211 86 57 a!) Use. 160bioe5 ete eres es een oa our 313 150 92 46

Very little detailed information is available as to the effects of forest and brush fires upon the fertility of the soils. It is known that such fires will add to the productivity of peat and muck soils, while it is likely that injurious effects are sometimes suffered by other soil types when used for certain crops. Minnesota Station Bulletin 220 says: .

Comparing crop production on the burned virgin sol (upland clay) with production on like soil unburned, sunflowers produced equally well or better ; hay about as good; oats and potatoes distinctly less. Clover catches remark- ably well in the ash.

In eastern North Carolina large areas of swamp land have been drained and are prepared for cultivation by burning the brush. All of the merchantable timber consisting of original growth of pine, cypress, gum, juniper, maple, and poplar has been cut out but the remaining unmerchantable timber and underbrush is very thick. The soils vary from heavy black loams to peat or muck and generally there is a layer, several inches in thickness, of turfy, vegetable mat- ter on top of the ground. For several years past, the approved method of getting this land into cultivation has been as follows: In the late summer or early fall all of the growth is cut down and allowed to lie where it falls. This growth is so thick and rank that when it is cut it often forms a continuous mat, sometimes 6 feet thick, over the entire field. With labor at $1.50 per day, the cost of cutting down the brush is from $8 to $10 per acre. During May of the following spring the brush is set on fire. A satisfactory burn is one which destroys all of the brush, a good portion of the logs and stumps, and all of the turf. While the ground is still hot from the fire, corn is planted by hand among the remaining logs and stumps. Figure 4 shows such a burned-over field. If a sufficiently good fire has been obtained, few weeds will appear and no cultivation will be


necessary. When the corn is ripe it is picked and carried in sacks to the edges of the field, or roads may be cut through the down logs so that the corn can be hauled out of the field. During the winter, the down logs and loose stumps are piled and burned. This prog- ram is repeated for four years before the field is plowed. Each year more weeds appear, more hoeing has to be done to keep them down but each year more logs, roots, and stumps are removed, thus giving more space for planting corn, and making harvesting easier. The fourth year finds the ground sufficiently free of débris to allow of rough plowing with a disk plow and the crop is then raised in the usual manner. For a number of years roots and pieces of stumps will be turned up after each plowing so that piling and burning or hauling wood out of the field is necessary until the field is entirely clean. It is claimed that under the conditions in this section, the crop raised each year during the four preparatory years before plowing will be from 30 to 40 bushels of corn per acre, and that the costs of preparing, planting, cultivating, and harvesting the crop will be between $15 and $30 per acre per year. Such a method of ‘land clearing can be economically followed: only where there is an abundance of cheap labor. The success of the method is also largely dependent upon the thoroughness of the initial burn and it is not always possible to secure a good burn.

Some people who have tried the above method advocate the fol- lowing variation of the plan: The timber is cut and burned as above, but the land is allowed to grow up to weeds for four years. In the fall of the fourth year, the weeds and new brush are cut, the stumps and down logs piled so that all can be burned off and the field plowed the next spring. It is claimed that the rank growth of | weeds keeps the sunlight from drying out the logs, brush, and stumps and so hasten their decay; that this method preserves more of the fertility of the soil; and that the cost of the entire operation will be less than the net cost where a crop is raised among the partially burned logs and stumps. However, this method has not been given a thorough trial as yet so that it is not definitely known that it has any advantages over the older method.

In the Delta section of Mississippi where the growth is largely gum with some oak, hickory, and maple, the following plan is used: After the merchantable timber has been cut, the remaining trees and brush which are usually dense and of heavy growth, are cut down in the spring after the leaves are out. This work is usually let out by contract and with labor at $1.50 per day usually costs about $10 per acre. The next fall, after the weeds have been killed by frost, the entire field is burned over. The logs remaining from this fire are pulled together by a log skidder, piled and burned. This work usually costs about $12 per acre depending on the success at- tained with the original fire. The next step is the gathering of the unburned tree tops, underbrush, and débris. A 2-horse hay rake is used for this work which is hard on the rake but does gather up the loose material quite cheaply. Raking, piling, and burning this brush costs about $12 per acre, but this also depends on the results of the first burn. The stumps are left in place to decay which they will do in from one to eight years depending on the kind and size of stumps and the extent to which they have been burned. After the


first plowing the field is again raked over to colleet the roots which were brought up by the plow.

In the arid sections of the Western States, the principle growth which must be removed prior to cultivation, consists of greasewood, sagebrush, mesquite, manzanita, chapparal, and other similar growth. Under some conditions of climate or fertility of soil, some of these shrubs approach trecs in size and in such case they may be removed by any of the methods herein described for removing stumps and trees. Where they do not exceed 5 to 6 feet in height they may be railed, piled, and burned. The railing is done by hitching two or more 2-horse teams to the ends of a railroad rail, a heavy log, or a piece of timber with a steel cutting edge, and dragging it across the field to break off the bushes. The field is usually gone over twice hut in opposite directions. It is most easily done ee the ground is frozen. The stumps which remain are then grubbed up, or left

Fic. 4.—An eastern North Carolina field where the growth has been cut down and burned. ; he first crop of corn has just been planted

to be plowed up, and the brush is raked into windrows and burned. A brush rake may be made of a 6-inch timber, 12 feet long, by bor- ing 2-inch holes through the timber, 10 inches apart, and inserting in each a wooden tooth about 3 feet long. The rake is then fastened by two timbers to the rear of a wagon to which a team is hitched.

In the Eastern States there are a number of trees which are very hard to destroy on account of peculiar root systems and a strong, persistent capacity for reproducing themselves. Sassafras roots strike perpendicularly into the ground for approximately 8 to 16 inches, then turn at right angles, rarely both ways, and pursue a horizontal course for about the same distance, when they split into numerous lateral feeder roots. The usual custom of cutting these roots off several inches below the ground serves only as a temporary expedient. The most satisfactory method of dealing with sassafras is to pull it out. Any clamp device, adjusted to a stout handle 5 to


6 feet long in such a manner as to give a strong leverage, will answer. The sassafras may be exterminated in one grubbing if the root is followed and cut beyond where it makes the angle, but this method is laborious. Constant and careful plowing, if maintained for several years, will gradually exterminate this bush but due regard for the condition of the soil will usually not permit such continuous plowing.

Persimmon and locust are very similar to sassafras and should -be treated in the same way. The locust roots are a little nearer the surface, more numerous, attenuated, and tenacious than the other two mentioned. Alder should be cut off in August at or below the crown, left where they fall, and burned the following spring.


In some places where the stumps are few and far apart it is possible to plow the brush under and immediately put the land in crop. All trees over 2 or 3 inches in diameter, or more than 6 or 8 feet high, should be cut down and all stumps more than 6 inches in diameter should be removed before plowing is attempted.

There is a great variety of kinds and sizes of plows being used for this work, depending in part on the growth and the soil, and in part on the owner’s opinion of the results obtained with the various makes of plows. Tractors are used for motive power because, although it would be possible to hitch enough horses onto the plow to pull it, they would not be as effective in breaking down the brush and small trees as is the tractor. The size of the tractor required depends on the power which it will be called upon to furnish. The smaller ones seem to give satisfaction where the work is within their pulling range. For heavy brush, the tractor should be strong in all its parts, the driving wheels should be equipped with extension rims and strong lugs, and it should have a large bottom clearance in order to pass readily over small stumps, débris, and stones. Some opera- tors prefer to hitch the tractor to the plow with a chain about 10 feet long to give the plow greater flexibility, while others prefer a rigid, but adjustable, attachment so that the plow can be backed up when it gets wedged under a stump. The plows and coulters are of many different designs, but a single-bottom plow, from 20 to 24 inches wide, with a landside about 514 feet long and 6 inches in width for large plows, and some form of standing coulter, seem to be the most popular. It is important that there be from 20 to 26 inches of clearance at the throat of a plow so that it will not be necessary to stop too frequently to clear the plow of brush and débris. The division of agricultural engineering of the University of Wis- consin has developed a brush plow with a throat clearance of 26 inches, which also has an offset in its beam so that the plow bottom is some 8 inches on the right side of the beam. This permits the space directly in front of and above the plow to remain relatively free so that most of the brush is caught and turned under by the rolling action of the furrow slice. A standing cutter, the upper end of which curves backward and to the right, was also designed to further prevent choking. This plow is shown in Figure 5.


A compilation of the returns to a questionnaire sent out to Minne- sota farmers gives the following information as to the equipment used for plowing under brush in that State’:

Average drawbar horsepower of tractors_________._____ 15. 25 Average size of cut, inches____......... 27. 50 Average depth of breaking, ineches_______-__....___ 6. 30 Average clearance of plow, inehes____________ ee 21. 00 Average cost for fuel, oil, and labor per 10-hour day: Gasoline or kerosene_____________-_-__-_ $5. 27 COUT <p Ng ema ite a a 1.39 Labor, at 40 cents per hour_____-____. 9. 00 POUND saphena e e $15. 66 AVOTARE -COSt Per Weren 2 oso oe 4. 24

The same report also says that the best time for plowing under brush is June, July and, possibly, August; that where brush has

I'ic. 0.—Brush plow developed by the agricultural engineering department of the Uni- versity of Wisconsin. The plowshere is offset 8 inches to the right of the beam to prevent choking with brush

been plowed under the land can be plowed a second time within two or three years after the first breaking; that more satisfactory work can be done when the ground is comparatively dry than when it is very wet; that after plowing the field is usually disked and sown to flax, hay, or grain; and that the crops grown for the first two years may equal those raised under normal methods of cultivation if all conditions are favorable.

There are some especially large and heavy plows made for this purpose which will plow 15 or 18 inches deep, but they are very expensive to operate and in some soils such deep plowing is not advantageous.

Where the conditions are favorable for plowing brush under the operating cost is undoubtedly less than the contract price of cutting, puing, and burning the brush. However, the cost of a plowing outfit is great, the plowing season is short and there is little other employ-

*Bul. 208, Agr. Eng. Div., Univ. of Minn., Investigations in Stump and Stone Removal.” ;


ment about a farm for such heavy equipment, so that this method of brush disposal is not economical for the farmer who desires to put only a few acres into cultivation in any one year.

Furthermore, when the brush is thick and heavy, the plowed surface is usually very rough and uneven, so much so that for several years plowing is difficult. If the brush is well covered it will gen- erally rot rapidly, although at least one case is on record where the farmer had to dig up and pull out most of the brush when he tried to plow the field the first year following brush plowing. Usually enough brush and roots are left uncovered and exposed to the air so that they will not readily decay, to interfere, to a marked degree, with plowing for several years. Where brush plowing is done it is gener- ally best to seed the tract and keep it in hay or pasture for three or four years. |

In parts of several Southern States the scrub or saw palmetto is the principal undergrowth. This plant has a strong horizontal root which grows along or under the surface of the ground, and from this root an immense number of vertical feeder roots extend down into the soil. Formerly the palmetto was grubbed out by hand at a cost of from $75 to $150 per acre, but usually it can be plowed under by a heavy breaking plow. When the horizontal roots are more than 8 inches in diameter and are present in considerable numbers it is almost impossible to turn them under with the ordinary plow. A plow has been used with some success for this purpose which has a vertical cutting edge like a heavy standing coulter beneath the beam. At its lower end, about 4 inches below the ground, there are two horizontal knives 18 inches long extending at an angle of 45° in both directions. After this plow has cut off the feeder roots the palmetto can be easily pulled by hand and thrown into wagons to be hauled. off and burned. With a small tractor about 2 acres of palmettos can be cut off in a day, and with a large tractor about 3 acres can be done in the same time. The manufacturers claim that heavy pal- metto land can be cleared by means of this plow for about $20 per acre.



The earliest and most primitive method of stump removal, that of hand grubbing, is still used extensively in spite of the fact that it is very hard and tedious work. It is such laborious work that men can not be hired for this purpose so long as other easier jobs are to be had. For small stumps up to 6 or 8 inches in diameter it is generally the most effective and economical method of removal. As the size of the stump increases the economy of this method tends to decrease, but even on large stumps, where labor is cheap, the costs are not excessive. A South Carolina planter says that during the winter of 1921-22 he paid out over $400 for grubbing stumps at a cost of 10 cents per stump, but that two years earlier he could not have contracted this work for $2 per stump, as men would not do such work at any price during prosperous times. In the summer of 1922 the contract price for grubbing stumps in the Mississippi Delta was 25 cents per stump. In southwestern Texas labor is or has been so Pee that grubbing out mesquite has been generally contracted or at a price of $15 per acre.


The tools required for grubbing are an ax, grub hoe or mattock, and a shovel. The advantages of grubbing out stumps are that it requires no investment in tools or equipment, it can be used equally well on thick or scattered, green or dead, rotten or solid stumps, and that it makes a clean job of removing the roots. The disad- vantages are that it is very slow and laborious, for large numbers of stumps it requires either many men or a long time, it leaves the stump and roots in such shape that the large ones are hard to handle and dispose of, and where labor has to be hired at high rates, it is expensive. Although other methods of removal may be quicker and easier, 1t should be borne in mind that unless the labor so saved can be put to some profitable use, nothing has been gained vy saving time. Large numbers of stumps are being removed by farm labor during intervals when there is no other profitable farm work to be done, and, under such conditions, the grubbing method should re- ceive careful consideration. |


Fire, one of the oldest methods of destroying stumps, is still used to good advantage under many conditions. Although it is a com- paratively simple matter to build a fire around a stump which will consume it, it is extremely difficult to burn the stump roots to a depth where they will not interfere with the cultivation of the field. The usual minimum depth required so as to be beyond any probable plowing depth, is 18 inches, since the ground about the stump is generally higher than the general surface, and because there will _ be considerable settlement in the ground when the stump is removed.

To obtain a good fire, the amount of heat present should be con- fined and conserved as much as possible and the air supply should be limited to just what is required for combustion. Stumps are burned with free or open draft, by char-pitting, and by devices for securing forced draft. :

Occasionally it is possible to build a fire on the outside of a stump which will burn so readily as to destroy most of the roots, but usually it is necessary to get the fire into the center of the stump, where little heat will be lost by radiation, in order to burn the roots. With the taprooted, pine stumps of the South, which seldom exceed <