THE GARDENERS' CHRONICLE OF AMERICA. 



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DYNAMITE AS A SOIL BUILDER. 



A quarter of a century ago, a fruit grower in Cali- 

 fornia, in digging holes for some fruit trees, came upon 

 hardpan which was nearly as tenacious as cement. He 

 used some dynamite with which to lircak up the hardpan 

 in order to get the holes deep enough tu |)lant the trees 

 at a right depth. 1; was discovered that the trees planted 

 in the dynamited holes made a much larger growth, and 

 better withstood the dry weather that fnllowerl. From 

 this discovery a general interest has grown in this method 

 f ])reparing the soil for trees. 



While there arc many instances where soil conduions 

 have been improved by the use of dynamite, this does 

 not follow with all soils, and it thus becomes important 

 to know and to understand the distinctions, writes George 

 T. Powell in The Field. In a soil that contains 63 per 

 cent, clay, with a yellow clay loam subsoil, one-half a 

 stick of 20 [Kr cent, dynamite put down two and a half 

 feet will loosen the top soil for si.x feet around and h\e 

 feet deep. The 20 per cent, strength is better than 40 

 per cent., as the slower explosive leaves the soil in better 

 condition. 



Dynamite, however, shuuld not be regarded as a digger 

 ■of holes for planting trees, as a properly placed tree 

 planting charge should be tamped in to insure the maxi- 

 mimi breakmg effect of the subsoil, and this tamping 

 prevents the excavation of a hole for planting the tree, 

 but the shock of the bla^t makes excavating with a shovel 

 easy. 



It is imijortant to follow this plan in setting out trees. 

 After the blast, shovel out the top soil and set it to one 

 side, then shovel out the subsoil until the jjoint where the 

 dynannte cartridge was exploded is reached. .\s a rule, 

 a cavity wdl be fovuid one to two feet in diameter: it i^ 

 iniportarit that this be filled with subsoil. If the tree is 

 planted without doing this, the subsoil will gradually drop 

 down into the hole, leaving the tree roots suspended in 

 the air, when the tree will die. Having filled the cavit)', 

 subsoil sliould be shoveled in to a ])oint just lielnw where 

 it is desired to place the mots of the tree. Tlien init in 

 half iif the top soil. Lay the mots un tliis top soil in 

 their natural position and cmer them with the remaining 

 top-soil and pack it in firmly 1)y treading it with the feet. 

 Then fill the remainder of the hole with subsoil. 



Several et^'eets are produced that Ijenefit the trees 

 planted in soil so treated. Excellent and quick drainage 

 is provided for the roots, which is essential to their health 

 and vigorous growth. A heavy, soggy or over-wet sub- 

 soil will retard the growth and bearing of trees bv several 

 years, as many o'f the fine feeding roots will perish when 

 confined for several weeks in such -oil. The breaking 

 up and loosening of a heavy subsoil mav l;e done much 

 more effectively through the use of dvnamite than is pos- 

 sible by digging holes three feet in diameter and fifteen 

 inches deep with a pick and spade, as is usually done. 

 The cost of digging the holes will be from two to three 

 cents per tree, against five to si.x cents for the dynamite, 

 but the dynamiting will be far cheaper when the greater 

 growth of the trees and the less uercentage of loss fol- 

 lowing dry periods are considered 



The subsoil should he drv at the tin^c of the blasting, 

 otherwise the efifect is detrimental rather than beneficial, 

 as a blast in wet subsoil throws the dirt hieh in the air 



and plasters it against the sides of the hole, failing to 

 crack the subsoil as it should, several feet around the hole. 



If the planiing is done in the spring, it is necessary 

 to wait until the subsoil is reasonably dry. Trees prop- 

 erly planted with dynamite will not die, but will grow 

 lapidly right through the dry summer, and will bear 

 fruit one to two years earlier than trees planted with 

 a spade. 



The next nnportant benefit that follows from the use 

 of dynamite is the more thorough aeration of the soil 

 that is produced. An aljundance of air in the soil is high- 

 Iv essential to plants. 



The roots of trees perform the necessary function of 

 taking up plant food that must first be made soluble, 

 when through the circulation of sap it is utilized in 

 making new la\ers of wood, foliage, fruit buds an<l fruit. 

 The OX} gen in the air performs an important part in 

 the processes going on, and in the changes which take 

 place in the chemical constituents that are present in every 

 grain or atom of soil, and which are necessary for the 

 growth of all vegetation. 



Where the soil is heavy, and in poor physical condi- 

 tion, trees are more subject to diseases that not only 

 retard their growth, but to a certain degree make them 

 unfruitful. Therefore, the better the soil is prepared by 

 making it more open or jjorous, and capable of taking in 

 the air freely and abundantly, the greater will be the de- 

 gree of health, vigor, growth and productiveness. 



Through the use of dynamite in the planting of an 

 extensive orchard of apple trees on a New Hampshire 

 farm of quite heavy loam soil, a very satisfactory growth 

 was obtained the first year, which was even more pro- 

 nounced the second. The soil and subsoil were favorable 

 for this method of preparation. 



Where the subsoil is of an open or porous character, 

 with a sandy loam top soil, the use of dynamite is not 

 advisable, for such subsoil should not be broken. The 

 foundation will become too loose or soft. The drainage 

 will lie made too excessive : the subsoil moisture will not 

 be so usable or effective in its upward movement, because 

 its medium has been broken up and changed, in conse- 

 quence of wdiich the trees will sufifer severely in times of 

 |)rolonged drought, and during heavy wind storms thev 

 will be blown over, fur their mots will not lie held by a 

 sufficiently firm soil. 



The use of dynamite is practical and economical, but 

 careful surveys of the soil and subsoil should first be 

 made, to ascertain whether they are suitable for the ad- 

 vantages to be gained by this method. 



These are some of the conditions that need to be un- 

 derstood in the preparation of the soil for tree planting. 



The method of blasting for and setting trees is about 

 as follows, depending somewhat upon the character of 

 the soil, de]ith of hardpan, etc. : 



The hole:^ are easily made liy driving a pointed steel 

 bar, \y2 inches in diameter and 4 feet long, to a depth 

 • from 2>< to 4 feet, as the depth of the hardpan calls 

 for. The bar should not be driven entirely through the 

 hardpan. but within from 6 to 12 inches. A one-half 

 poiiiul ^tick of 20 or 25 per cent, dynamite is primed 

 with ca]_) and fuse and carefully lowered and tamped. 

 The first six inches of earth should be tamjied very light- 

 ly and the balance should be tamjied as tightly as can be 

 (lone with ;i wooden tamping stick. The charge is now 

 readv to explode, which is done by lighting the fuse. 

 After the explosion, a barrel-shaj^ed chamber is usually 

 found 12 or 18 inches below the surface. This should 

 be filled to a proper flepfh for the tree with rich humus- 

 bearing earth and the hole is ready. Set the tree and 

 fill the balance of the hole with rich earth and it has every 

 chance to live as far as its root bed is concerned. 



