54 AGRICULTURE ON THE PACIFIC SLOPE 



bottom) just such a case; and it also shows how much 

 better the water penetrated from the deep furrows 

 than from the shallow ones. 



Furrows 5 a/xf 10 inches deep in Sandy Loam Soil 



Water runnfng^n eacft t seven 



FIG. 28. The upper diagram shows how much better the water goes into 

 the soil from the broad furrow (at the right). The diagram at the bottom 

 shows that the water will not go down into the hard subsoil (plowsole). 



To find out what becomes of our irrigation water, we can 

 dig down with a spade, or bore with a post-hole auger; or 

 we may use the "soil probe/' a square steel rod with a cross 

 handle like a carpenter's auger at the top, and pointed at the 

 lower end. The moist or wet soil is always darker- colored 

 than the dry. 



This probe should never be turned around, but only 

 twisted a little way, back and forth. It then goes down 

 easily when we bear upon it (figure 29), and, with a little 

 practice, we can feel when the subsoil is hard, whether there 

 is "hardpan" or sand, and also how far the water has 

 soaked down. 



