THE ROOT SYSTEMS OF CEREALS. 115 



Springs. Here the typical grass cover of Bulbilis and Bouteloua on the 

 harder silt-loam alternates with the mixed -prairie cover on the sandy- 

 loam (cf. p. 66). Winter wheat, spring wheat, and rye were all ex- 

 amined on land that had been broken for only two seasons. The winter 

 wheat and rye had both been preceded by corn, having been drilled 

 about the middle of September. The spring wheat was also preceded 

 by corn. At the time of these examinations, on June 25, the winter 

 wheat was just coming into the dough stage, while the spring wheat had 

 just begun to blossom. The former had an average height of 1.8 feet, 

 the latter of only 1.7 feet (plate 22, a). The surface 10 inches of soil 

 consisted of a fine silt-loam underlaid by 1.7 feet of dark chocolate- 

 colored clay, which, although moist, because of its somewhat jointed 

 structure, broke out in lumps. At 2.5 feet depth the soil became some- 

 what chalky and sandy, while 10 inches deeper it gave way to a very 

 fine yellow sand. It was very dry below 2.5 feet. The average working 

 depth of the winter wheat was found at 2 feet. The roots were abun- 

 dant to this depth. Some roots were found deeper, even penetrating 

 a little into the dry sand. Unlike the roots of the dominant native 

 grasses, those of wheat do not run so parallel with the soil surface, 

 although they take an oblique direction downward at such an angle 

 that at a distance of 5 to 8 inches from the base of the plant they may be 

 only 3 to 5 inches deep. The root system was well developed and 

 profoundly branched, the branches often being 2 or 3 inches in length. 

 Although the surface soil was much more mellow in the field of spring 

 wheat, due to the disking of the ground before drilling the wheat in the 

 spring, the water penetration was no greater. The working depth 

 was 2 feet, below which the soil was dry and no roots penetrated beyond. 

 The lateral spread and degree of branching were about the same as that 

 already described. Under both crops the roots of native plants were 

 found extending 7 feet deep and may have penetrated even deeper. 

 The field of rye was about a quarter of a mile distant. The ground 

 was level and the soil almost identical with that just described, but the 

 water penetration was not so great. The crop was in the flowering 

 stage and about 2.3 feet in height. The roots had a working depth of 

 2 feet, below which few or none penetrated. They had a wide lateral 

 spread, reaching horizontal distances of 0.8 to 1.3 feet or more on either 

 side of the plant at a depth of 0.2 to 0.4 foot. All of the roots were 

 exceedingly well branched and were especially abundant in the crevices 

 of the somewhat jointed soil. The rather limited root penetration 

 shown by these crops on land formerly covered by short-grass vegeta- 

 tion is in striking contrast to the deeper-rooted ones on the lighter soil 

 type in adjacent fields, as indicated by mixed prairie. Moreover, 

 where rainfall is sufficient to support a growth of mixed-prairie species 

 on hard lands, a far better development of crop plants is found. 



