August, 1012.] 



107 



USE OP EXPLOSIVES IN 

 AGRICULTURE. 



It has been usual till lately to give 

 dynamite a wide berth, but now the ex- 

 plosive has come to be considered a 

 useful adjunct of agriculture, and the 

 demand for it in the preparation of lands 

 bids fair to surpass that for mining pur- 

 poses. The various uses to which it is 

 put are for tree-planting, subsoiling, 

 ditching, removal of old tree stumps, 

 boulder blasting, road-making, &c. The 

 three first mentioned are perhaps the 

 most important and will therefore be 

 described in detail- 



Tree Planting. 



Among the different kinds of soils 

 met with are some of a shallow des- 

 cription underlaid by a hard pan 

 or at least a compact impervious 

 subsoil. In such soils the roots have 

 practically to confine themselves to the 

 surface soil for their food supply, which 

 naturally gets rapidly exhausted. 



In many cases the subsoil is rich in 

 plant food — potash, phosphoric acid, lime, 

 &c. — but in the absence of water which 

 cannot penetrate the hard under-surface 

 these supplies are not available to the 

 plants, since moisture is a sine qua non 

 for the solution and absorption of plant 

 food. 



The U. S. A. Experiments 

 have shown that frequently the soil 

 contains "05 and '07 % of phosphorus 

 and potash respectively, while 3 or 4 feet 

 below the percentage lises to "15 and 13. 



In using dynamite for tree-planting a 

 hole 4 to 5 feet deep and 1£ to 1$ inches 

 in diameter is first made, at the bottom 

 of which the cartridge is placed provided 

 with detonator and fuse, and the hole 

 well filled in. The result of the explos- 

 ion is that on the removal of the 

 loosened earth not only is a suitable 

 hole for planting found, but the ground 

 is fissured for a considerable distance 

 from the hole and the compact layer 

 disintegrated. 



It has been observed that trees planted 

 in land prepared in this way thrive very 

 much better than those put in holes 

 prepared in the usual way. The roots 

 are found to be larger and more vigorous, 

 being free to spread in all directions. 

 Water can now penetrate the soil and 

 dissolve out the plant food stored up 

 there, while at the same lime an under- 

 ground reservoir of moisture is found 

 which bids fair to render the trees 

 drought-resistant. 



The Breaking up op the Soil 

 in this manner is possible even in planted 

 up lands carrying old non-bearing trees 

 standing in an impoverished soil with a 

 hard 6ubsoil below, and has been done 

 with good results in crops. 



Soils prepared by digging are opened to 

 a depth of about 18inches or 2 feet, while 

 with dynamite they are loosened to a 

 depth of 3 or 4 ft., and at less cost. It 

 has been estimated that in Ameiica the 

 cost of dynamiting land is between £ 210 

 and £5 per acre according to the nature 

 of the soil treated. 



It has further been found that where 

 supplies have been put into holes pre- 

 pared by dynamite to replace trees 

 killed by insects or fungoid pests, the 

 new trees have not been troubled by the 

 pests. 



Subsoiling for Cereal and 

 other Crops. 



Por this purpose the holes are prepared 

 from 15 to 25 ft. apart, and the operation 

 could be carried out even witn a standing 

 crop if the holes are made deep enough. 

 Digging Ditches. 



For this holes are dug along the line of 

 ditch at intervals ot from 1 to 2 it. and 

 to a depth of l8"to2tt, aceoidiug to 

 nature of soil aud requirements for 

 ditch. Por very wide duches more than 

 one row of holes is provided.— (Sum- 

 marized from Agricultural JournuL uf 

 the Union oj <b\ Africa.) 



