112 ROOT DEVELOPMENT IN THE GRASSLAND FORMATION. 



The root development of the smaller cereal crops was also examined 

 at Burlington, Colorado. This station is about 10 miles west of the 

 Kansas-Colorado State line and in the midst of great stretches of short- 

 grass plains of which Bulbilis dactyloides forms the consociation. The 

 natural vegetation has been described on page 74, in connection with 

 the description of the roots of buffalo grass, which were examined in an 

 area adjoining the fields of crop plants. This whole area, lying about 7 

 miles northeast of Burlington, was quite level. 



A field of mixed oats (Yellow Kherson in part) and one of Turkey 

 Red wheat were examined. In both fields the small grains were the 

 second crop. The first crop after breaking on the oat land was millet, 

 while on the wheat land a crop of sorghum had been raised. The soil 

 was disked and harrowed and the wheat was drilled about October 1. 

 After similar preparation of the soil in the spring, the oats were drilled 

 on April 16. The fields were visited June 29, 1919. The oats had just 

 finished blossoming and were in the milk stage. The wheat was some- 

 what more mature, the kernels being in the dough stage of development. 



In both fields the stand was good; the oats averaged 2.2 feet and the 

 wheat about 2.5 feet in height. The trenches were dug after complet- 

 ing work on the natural vegetation, and the much greater ease with 

 which the tilled soil at all depths could be excavated was very pro- 

 nounced. Indeed, the soil was quite moist to the maximum depth 

 examined (7.5 feet), being easily molded into firm lumps with only 

 slight pressure of the hand. No "hardpan"' was in evidence, the soil 

 being mellow throughout and easily spaded. Similar conditions were 

 found in adjoining fields of rye and barley, growing on land that had 

 been broken for 3 years. This is in sharp contrast to conditions in the 

 native sod, where the hard, compact soil was powdery below a depth of 

 3.5 feet. An examination of the rainfall records shows that an excess of 

 nearly 3 inches over the normal precipitation had occurred the preced- 

 ing December and 4.3 inches in June. It is probable the run-off was 

 very much higher from the sod than in the fields of grain. 



The oat roots were found to be very abundant to a depth of 4 feet ; the 

 working depth for the wheat was about 2 inches less. The maximum 

 depth of oat-root penetration was 5.3 feet, while several wheat roots 

 were traced to 5.4 feet in depth. At 5 feet the soil contained enough 

 moist clay to stick to the spade. Roots of both Lygodesmia juncea and 

 Bulbilis weie found extending well below the level reached by the roots 

 of crop plants. They aie easily distinguishable from the thicker, more 

 watery, fragile root-ends of oats and wheat, which are thickly beset 

 with root-hairs to which the soil clings tenaciously. Although both 

 wheat and oats had well-branched root systems, the latter had more 

 numerous branches, and most of these were of larger diameter. 



A field of rye, the third crop following sorghum and barley, was next 

 examined. The preparation of the seed-bed was similar to that already 



