ARBORICULTURE. 



^45 



DRY FARMING. 



This is a term employed in recent 

 years, to designate the method employed 

 in the semi-arid regions where water is 

 not available for irrigation, and consists 

 in frequent stirring of the surface soil, 

 keeping it pulverized, tO' retain and to 

 conserve the moisture which has been 

 deposited, usually as snow, in order that 

 vegetation may receive the benefit of 

 this moisture during the summer or 

 growing season, instead of permitting it 

 to escape by evaporation into the at- 

 mosphere. 



The theory upon which this moisture 

 is made available for the roots of plants 

 is, that water absorbed by the soil dur- 

 ing the winter rains or snowfall as it 

 melts, remains in the soil until during 

 the hot, dry months, when it is raised by 

 capillary attraction to the surface, and is 

 absorbed by the drier atmosphere, and 

 carried away by the winds. 



Sa long as there is a hard surface the 

 capillary attraction continues to lift the 

 water from the lower subsoil to the sur- 

 face soil and thence to the atmosphere. 



Pulverizing the surface, especially 

 after it has been compacted by rain, 

 breaks up the capillary attraction by de- 

 stroying the cells or tubes in the soil, and 

 prevents the escape of the moisture. 



This is practically upon the same prin- 

 ciple that water in the earth enters the 

 millions of mouths of the fibrous roots 

 of a tree, and ascends to the trunk, and 

 through that medium tO' the branches, 

 finally reaching the leaves at the top- 

 most branches of the tree — a living 

 pump, by which tons of water are lifted a 

 hundred or more feet by the action ol the 

 capillary attraction. 



Where there is a slight annual rainfall, 

 say 15 inches during the year, there 

 falls upon the earth, and may be ab- 

 sorbed into the soil, upji. each square 

 mile of surface, 1,115,136 tons of water, 

 enough, if properly constived, to enable 

 the soil to produce a good crop in any 

 season. 



By using a co^mmon: harrow, and run- 

 ning over the land frequently during the 

 growing season, the greater portion of 

 this moisture may be conserved, and if 

 the surface soil is broken up tO' a good 

 depth, it will absorb) practically all the 

 water which falls. Yet. if the plowing 

 be very shallow, or the surface is per- 

 mitted to become solidly compacted, the 

 sponge which the soft soil becomes is 

 lost, and the greater portion of the pre- 

 cipitation runs O'fif to feed the rivulets, 

 streams, and thence to- the sea. 



There are various implements recom- 

 mended for summer cultivation in dry 

 farming, but while any will answer, 

 there is nothing better than a harrow or 

 light-nmning cultivator. 



Deep plowing in autumn and spring, 

 with frequent shallow cultivation, is the 

 best. This method was frequently ad- 

 vised by the editor oi ArboricuIvTurk 

 forty years ag'o, and has steadily grown 

 in favor by farmers, although in the arid 

 West it is better understood. In plant- 

 ing forest trees upon Western lands 

 where water is scarce, this method will 

 produce excellent tree growth, but the 

 fact must not be lost sight of that the 

 crust must not be allowed to form or 

 remain, but at once go over the planta- 

 tion with the harrow. 



Near Denver, Col., by this method, 

 excellent tree growth of both fruit and 

 forest trees has resulted in pure sand 

 without one drop of irrigation water. 



