THE ROOT SYSTEMS OF CEREALS. 117 



The roots spread laterally in the surface 0.5 to 0.8 foot for distances 

 of 0.4 to 1.3 feet before ending or turning downward. The first 4 to 6 

 inches of roots at the base of the plant were almost woolly with dense 

 masses of root-hairs to which the sand clung tenaciously. The roots 

 soon began to branch, with delicate, hairlike branches 0.5 inch to 3 or 4 

 inches in length, some being even longer. They ran off in all directions, 

 even obliquely upward, and were fairly well rebranched to the second 

 order. The main roots, which were rather tough, appeared like coarse 

 threads. The branching in the first 2.5 feet of soil was not so profuse 

 as at greater depths. Here great numbers of fine, poorly rebranched, 

 threadlike laterals occurred to the ends of the roots at a depth of 4 or 5 

 feet. They were mostly 0.5 to 2 inches in length, but frequently 

 several inches long. In places as many as 10 to 30 were found on a 

 single inch of the root. The working depth was 4.2 feet, and no roots 

 were found below 5 feet. After several root systems were examined on 

 the four walls of the long trench, a drawing (fig. 34), was made to show, 

 as nearly as possible, all the root characters described. 



At the United States dry-land experiment station at Ardmore, South 

 Dakota, some examinations of the roots of crop plants were made 

 in correlating their development with those of the roots of the mixed 

 prairie. A description of this mixed prairie may be found on page 67 (cf. 

 also plate 3, a, b). Since the soil, even on this rather level area, is far 

 from uniform, it will be necessary to point out the variations in the 

 two fields examined. 



In the field of Turkey Red wheat the very hard, tenacious, brownish- 

 black Pierre clay gave way at a depth of 3.7 feet to a poorly disinte- 

 grated gravelly sand intermixed with some clay. The degree of com- 

 pactness of this soil should not be overlooked. The writer has excavated 

 roots in scores of places in many different States, but in no other soil 

 (once through the surface foot) has greater difficulty been experienced 

 in excavating a trench preliminary to examining the roots. It is quite 

 remarkable how roots can penetrate soils which are so compact even 

 when quite moist. 



This land had been broken for 7 years and had lain fallow the pre- 

 ceding season. Wheat was seeded at the rate of 45 pounds to the acre 

 on September 9. It came up well in the fall, and when harvested, 

 about July 10, it had an average height of 2.6 feet. The yield was 

 estimated at 30 bushels per acre (plate 22, b). Roots were very abun- 

 dant to a depth of 3.3 feet, some penetrating entirely through the clay 

 and 0.3 to 0.4 foot into the gravelly sand beneath. The soil was quite 

 moist to the maximum depth excavated, about 5 feet. 



About 100 yards from this trench, another was dug in a field of oats. 

 The variety is known as "Sixty-day" oats and is very similar to the 

 White Kherson. This crop followed one of corn, the soil having been 

 disked and the oats seeded at the rate of 48 pounds per acre on April 2. 



