THE 1RR1 GA110N A GE. 247 



age irrigator may produce even better crops with half the usual 

 amount of water if he understands fully and clearly all the scientific 

 principles of plant life and fully comprehends the real principles of 

 moisture movements in the soil; how under certain climatic and soil 

 conditions the moisture is lost by evaporation from the soil; how 

 under other soil conditions evaporation may be reduced to the mini- 

 mum and practically all the moisture that percolated below the sur- 

 face may be atored and conserved in the soil and made available to 

 the growing plant. 



It is a conservative estimate to say that three-fourths of all the 

 rainfall throughout the semi-arid sections is lost by evaporation, whil 

 it is believed by those most familiar with these facts, that at least 

 three-fourths of the rainfall may be retained and conserved in the 

 soil by proper cultivation and far the greater part of this made avail- 

 able to the growing plants. What is true with reference to the rain 

 water is very largely true of irrigating water. 



Whether the necessary water is supplied by irrigation or by rain- 

 fall the growth and final crop yield is very largely governed by the 

 physical condition of the soil, which is good or bad, just in proportion 

 to the manner id which it is treated, how and when the work of fitting 

 the soil is applied, and what the applied condition of the soil is when 

 the work is done. 



There are many things to consider in the growth and development 

 of a crop besides the mere question of supplying the seeds or plants 

 with soil and water. When we take into account the fact that fully 

 95 per cent of all plant growth comes from the atmosphere, and that 

 a large per cent of this water reaches the plant through the soil, we 

 are confronted with a fact not fully appreciated by most tillers of the 

 soil. 



Much has been said in the past with reference to sub-irrigation, 

 but the question has never been fully discussed. There are many 

 ways in which the principles involved may be applied. It is not nec- 

 essary that tiling or perforated pipe be placed beneath the surface 

 soil, and water kept running in and through it in order to secure the 

 direct results from the principles involved. The water may be stored 

 in the soil below, either from the rain or from the ditch, and by culti- 

 vation or stirring the surface soil, producing what is known as the 

 soil mulch, the moisture held there may be made available to the 

 growing plants, provided the proper preparation and fitting is given 

 that portion of the soil where the seed is placed and which the roots 

 permeate for plant food and moisture. One of the strongest evi- 

 dences and best illustrations we have of this fact is the growth and 

 development of wheat or other plants covered by a heavy snowdrift, 

 as compared with the part of the same field that was left bare of 



