66 CROPS AS FEEDERS 



Because its draft upon the soil is comparatively light and since it 

 is able, because of its well-developed root system, to draw the 

 last trace of available elements from the soil, this crop yields from 

 fair to good even though the soil is too poor for other crops. In 

 time, however, even timothy will yield poorly. The sod is plowed 

 up, and if not manured, the crops on this poor timothy sod are 

 scant. Farmers have often observed that when a field is sown 

 half to clover and the other half to timothy, and both sods are 

 plowed, manured and planted to corn, the corn on the clover sod 

 is much the better crop. Since these facts have been generally 

 observed, it is inferred that timothy must be a "soil robber." 



It is true, nevertheless, that clover is a much better crop to 

 grow because of its higher feeding value, and because it can gather 

 nitrogen from the air by means of bacteria that live in the nodules 

 on its roots. 



Some Plants Have Strong Feeding Powers. It has been 

 demonstrated that some crops, better than others, can secure their 

 requirements of mineral elements from insoluble substances in 

 the soil. Buckwheat, for example, can secure its need of phos- 

 phorus from soils low in available phosphorus better than oats, 

 corn or millet. Perhaps this explains why buckwheat does so well 

 on poor or exhausted soils, and why it is a good crop to grow to 

 plow under as the first step in the improvement of such soils. 



In general, a plant that can grow well on poor soil may be 

 regarded as having a strong feeding power, while a plant that can 

 not grow well except on a very rich soil may be regarded as having 

 a weak feeding power. 



Barley Requires a Richer Soil Than Oats. When we compare 

 the amount of the elements required by average good crops of 

 barley and oats, we find but little difference. A soil capable of 

 producing forty bushels of barley per acre would easily produce 

 from sixty to sixty-five bushels of oats. In that case the oats 

 would draw heavier upon the soil than barley. Nevertheless, it is 

 generally recognized that a richer 2 soil is required to grow common 

 barley than oats. For an explanation we must study the habits 

 of these two crops. 



Barley does not develop so extensive or deep a root system as 

 the oat, and hence draws on less soil for its needs. It also has 

 a weaker feeding power and it matures earlier. Thus barley 



2 A rich soil is understood to mean a soil having a good supply of available 

 plant-food elements, as indicated by good crop growth. 



