180 FIRST PRINCIPLES OF AGRICULTURE. 



ment of the root system. The root formation of the 

 winter cereals is encouraged by close contact with moist 

 earth, hence a soil of a compact nature is desirable for 

 their normal growth ; loose, shifting sands are unfavor- 

 able, moist clay loams are favorable. 



Method of Feeding. — The general tendency of the 

 cereals is to absorb food from lower layers of the soil 

 as the plant grows older ; that is, the roots near the 

 plant die ; and only the fibrous roots at a distance and 

 in the lower layers of soil possess the power of absorbing 

 food : hence, to ensure maximum and continuous growth 

 throughout the whole period of life, the entire surface 

 soil must be enriched. 



Power of Acquiring Food. — The cereals are able to 

 acquire food from the insoluble phosphate and potash 

 compounds of the soil in a greater degree than root 

 crops. They are on this account called "voracious feed- 

 ers." Oats and rye possess this characteristic more 

 largely than wheat or corn. Where the climate is suit- 

 able, oats and rye will — other conditions being equal — 

 thrive proportionately better on poor soil than wheat 

 or corn. 



These crops are unable to feed to any extent upon 

 the insoluble nitrogen of the soil ; they absorb the nitro- 

 gen necessary chiefly in the form of nitrates. This form 

 of nitrogen must, therefore, be directly applied, or the 

 soil must have been previously supplied with nitrogenous 

 materials that decay readily. 



On soils well supplied with mineral constituents, wheat, 

 oats, and rye — both because they are uncultivated crops, 

 and because their greatest development is in the early 



