104 SOILS 



when his crops get weedy, especially if they are 

 close to the road. So he begins to stir the soil with 

 a cultivator and to dig into it with a hoe; then the 

 chief mission of weeds in farming has been ac- 

 complished. From the beginning of husbandry 

 they have pricked men on to till the soil. Now we 

 know of other reasons for keeping the soil stirred 

 around our plants, reasons that are important 

 enough to make the best farmers till when there are 

 no weeds. But weeds will always remain the spur 

 of the sluggard and a fairly reliable tillage guide 

 to the rest of us. 



TILLAGE TO SAVE WATER 



Aside from preparing the soil to receive the crop 

 and killing the weeds that would compete with the 

 crop, tillage accomplishes another result that may 

 be even more valuable to the farmer. It saves 

 soil water, as has been described in the preceeding 

 chapter, by establishing a mulch, whicn makes it 

 impossible for much water to evaporate. The 

 amount of water that is saved by keeping the sur- 

 face of the soil thoroughly stirred may be as much 

 as one-third of the total amount that the soil re- 

 ceives. Snyder found that the soil of a corn field 

 which had been cultivated frequently contained 

 17 per cent, of water in the layer of soil from 9 

 to 17 inches deep, while the same layer of 

 soil in another part of the same field, but which 

 had not been tilled, contained only 12 per cent, 

 of water. 



The efficiency of a soil mulch in preventing the 

 escape of soil water needs no further proof than 

 observation in orchard, field and garden. During 

 a summer drought the corn leaves shrivel first 



