108 ROOT DEVELOPMENT IN THE GRASSLAND FORMATION. 



this station, which is somewhat more than 4 feet, while oat roots 

 are about 4 feet long normally. He washed out the roots of win- 

 ter rye gi owing in the fertile loam soil. On July 7 the roots had 

 reached a depth of only 3 feet, "the supply of roots being lighter than 

 commonly found by this station for cereals." He suggests that "in 

 this northern latitude, where the ground freezes deep in the winter, it is 

 probable that the soil is too cold, at a depth greater than 3 feet, prior to 

 July 7, to prove a suitable zone for cereal plants." 



Ten Eyck (1904) working at Manhattan, Kansas, states that the 

 roots of Red Winter wheat planted on October 11, at maturity on July 

 7, reached a depth of fully 4 feet in the hard subsoil underlying the 

 fertile compact loam. Fine, fibrous roots extended to the very surface 

 of the ground. The deeper slender roots did not branch much, and he 

 estimated that the absoibing surface of the roots was greater in the 

 first foot of soil than in all the lower soil. He describes oat roots 

 excavated from a fine compact loam with a rather clayey subsoil. The 

 roots were examined July 11, 103 days after planting in diills 8 inches 

 apart. Seveial of the main roots were washed out to a depth of 4.5 feet 

 and a few extended even deeper. The larger side-roots interlaced 

 between the drill rows within 2 inches of the surface. 



The preceding data, which will be summarized at the end of the 

 chapter, are sufficient to warrant the conclusion that crop plants, like 

 then native predecessors in prairie soil, are deeply rooted. 



ROOT DEVELOPMENT IN SHORT-GRASS PLAINS. 



Examinations of the root development of the smaller cereals were 

 made at six typical stations in the short-grass plains. It has been 

 pointed out on page 13 that in this plant association tall-grasses and 

 most of their accompanying herbaceous societies are not present 

 because of the light, unevenly distributed precipitation, which, with the 

 high run-off from the compact silt-loam and the high evaporating power 

 of the air, result, normally in a low available water-content. More- 

 over, the short-grasses, especially Bouteloua gracilis and Bulbilis dac- 

 tyloides, being able to complete their growth and mature seed in a 

 short period, compete successfully with the slower developing prairie 

 species, the combined result of all these conditions being the almost 

 entire absence of the latter, except perhaps very locally and in the most 

 favorable situations. Consequently the short-grass vegetation in- 

 dicates an entirely different set of environmental conditions than the 

 tall-grass prairies, as is shown also by the development of crop plants. 



Near Yuma, Colorado, and in a level field adjacent to one covered 

 with a close sod of buffalo grass (described on p. 72), the roots of 

 Turkey Red wheat and winter rye were examined. The rye land had 

 been broken for only two years, the wheat land for about four. Both 

 had been cropped the preceding season with sorghum and corn respec- 



