This, together with the fact that the action of an explosive on 

 soil causes it to become thoroughly mellowed and aerated, causes trees 

 planted in blasted holes to snow much stronger and healthier growth 

 than trees planted under old conditions. 



In order to give those who may not understand the subject an 

 idea of the scientific principles of plant growth, we will quote W. J. 

 Spillman, Agriculturist in charge of Farm Management Investigations, 

 Bureau of Plant Industries, U. S. Department of Agriculture. He says 

 in a recent bulletin : 



"Plant food is dissolved in water. While a plant is growing, a 

 constant stream of water flows up through it and evaporates at its 

 leaves. For every pound of increase in dry matter made by the plant, 

 from 300 to 500 pounds of water flow up through it. 



"Plants in their growth make use of thirteen elements, nine of 

 which they secure directly from the soil. These are called the mineral 

 plant foods. They are phosphorus, potassium, calcium, magnesium, 

 sodium, iron, silica, chlorin and sulphur. Soil consists mainly of small 

 particles of rock. Nearly all kinds contain more or less of these min- 

 eral plant foods. Every year the soil water dissolves off a thin sur- 

 face layer from each particle and plants appropriate this water, thus 

 securing their mineral plant food. Hydrogen, another important ele- 

 ment of plant food, is also secured from water. 



"In order to produce a ton of hay on an acre of land, it is neces- 

 sary that the growing grass pump up from that ground approximately 

 500 tons of water. In order to supply this enormous quantity of water, 

 the soil must not only be in a condition to absorb and hold water well, 

 but must be porous enough to permit water to flow freely through it. 



"In addition to acting as a water carrier for plant life, soil must 

 permit a proper circulation of air through it. Nearly half of the 

 volume of ordinary soils is occupied by air spaces. Soil which becomes 

 so compact as to .stop the air passages, is too wet for most crops and 

 needs drainage, for plant roots must be supplied with air and the soil 

 must be porous enough to permit of its free circulation. One of the 

 most important objects of plowing is to loosen up the soil and mix 

 fresh air with it." 



Orchardists and nurserymen who have had long experience in plant- 

 ing trees in holes prepared by dynamite blasts, have learned that com- 

 pact subsoil is broken up by the blasts, which enable the land, thus 

 made porous, to absorb plenty of water in rainy weather and store it 

 up for the use of growing plants in dry weather. As Mr. Spillman 

 says, this water in ascending to the plant roots carries with it the 

 many necessary soluble fertilizing elements. 



Few persons realize the depth of tree root expansion. In one of 

 the "Farmers' Bulletins" issued by the United States Department of 

 Agriculture, a cross section of orchard land is shown which we repro- 

 duce on the opposite page. Note the scale on the sides, indicating 

 that this tree has sent its roots downward 21 feet into the soil. This is 

 natural growth. Under normal conditions a healthy tree will seek its 

 food in this way; but suppose a layer of hardpan or compact subsoil 

 is encountered at a depth of two to six feet? The roots must then 

 spread out near the surface for twenty feet or more. The result of 



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