268 DRY FARMING 



food; the organic matter which it contains increases the 

 power of the soil to hold moisture and to resist blowing. 

 On drifting soils the only argument against the use of 

 manure when intelligently applied is the cost of apply- 

 ing it. The application of manure as a surface dressing 

 on the more exposed portions that are likely to blow first 

 is a preventive measure that should come into general 

 practice. 



The plowing under of weeds in the fallow year, or the 

 early spring growth of sweet clover or of the perennial 

 grasses, is probably the only green manuring it will be 

 found profitable to practise in our dry areas at the 

 present time. The growing of green crops through a 

 whole season in order to have a large growth to plow 

 under to increase the organic matter content of the soil 

 will not likely ever come into general use in the West, for 

 the reason that the organic matter thus added to the soil 

 is secured at the expense of an enormous quantity of soil 

 moisture which is itself generally the limiting factor in 

 crop yields. On soils that are low in organic matter in 

 areas of light rainfall, it is questionable how far this 

 practice may be carried before its waste of soil moisture 

 will result in making the remedy more to be feared than 

 the disease. 



223. Modifying the Structure of the Soil.— Soil drift- 

 ing occurs chiefly on the fine textured soils — the sandy 

 types and the heavy clays that slake down to a fine 

 powdery condition on top. The fallow generally suffers 

 the most, although fall plowed land is not free from 

 erosion and spring plowed land on some soil types oc- 

 casionally blows. The smaller the soil particles are and 

 the drier they are the greater the probability of their 

 drifting. The problem is therefore one of pre- 

 venting the soil becoming too fine and too dry on top. 



