54 



Development and Activities of Roots of Crop Plants. 



ditions also prevailed throughout July. Well-distributed rains furnished 

 abundant soil-moisture (table 10); soil and air temperatures and humidity 

 were favorable (fig. 20), and evaporation was not excessive (table 11). 



The roots on the upland had penetrated to a maximum depth of 5.2 feet 

 and were fairly abundant to the 4.2-foot level. Those on the lowland were 

 slightly deeper. The greatest depth of penetration was 5.7 feet and several 

 occurred at the 5-foot level. In both areas the tap-root was the prominent 



A Ei 



Fig. 25. — A. Alfalfa 132 days old. B. Sweet clover 115 days old. 



feature, varying from 3 to 5 mm. in diameter. Laterals were not abundant 

 below the surface 1.5 foot of soil. The longest did not exceed 6 or 8 inches. 

 The roots penetrated nearly vertically downward and were furnished at irreg- 

 ular intervals with short, mostly poorly branched or unbranched rootlets. 

 These occurred at intervals of an inch or less, becoming smaller near the 



