﻿20 BULLETIN 4, U. S. DEPARTMENT OF AGRICULTURE. 



where many of the tufts had died out, the tussocks were often torn 

 asunder by the sheep passing over them a couple of times. In loose 

 soils, as stated, there is danger of getting the seed planted too deeply 

 by the employment of this scheme. This difficulty may be largely 

 obviated by driving the band over the area before as well as after 

 scattering the seed. By so doing the loose hummocks and elevated 

 points are mostly smoothed down before the seed is scattered, and 

 too deep planting is thereby at least partly eliminated. Even then, 

 however, the forage stand secured on areas of loose soils where the 

 seed was trampled in was not usually as dense as where harrowing or 

 brushing was employed, but much better than where no soil treatment 

 was given subsequent to sowing. 



COMPARATIVE MOISTURE REQUIREMENTS AND ROOT DEVELOPMENT OF THE SEEDLINGS. 



During the first year of growth — that is, during the seedling 

 period- — a rather marked variation was found to exist in the ability of 

 the species in question to become established. This fact does not nec- 

 essarily mean that one species is more drought resistant or can take 

 more water from a given soil than another, but rather that there is a 

 difference in the depth, spread, and general development of the root 

 system through which the water is secured. 



When young, the species of similar growth- form and of the same 

 age produced very nearly the same height growth. It was also found 

 that the species which naturally nourish in the drier habitats pro- 

 duced roots of similar development so far as concerned their depth 

 and spread. It was found, however, that the ratio between the height 

 growth and the depth of the root in the case of species which natu- 

 rally prefer medium moist soils was different from that developed by 

 species which prefer moist habitats. As a concrete example, four 

 grass species, smooth brome grass, timothy, Kentucky blue grass, and 

 redtop, which are known to have different moisture requirements, 

 were grown in a common habitat, and at the end of the fifth week 

 after germination the respective species were carefully examined to 

 ascertain the average depth of the root development. Smooth brome 

 grass had extended its roots to a depth of 3.1 inches, while timothy, 

 Kentucky blue grass, and redtop had made an average root develop- 

 ment of 2.7, 2.5, and 1.9 inches, respectively. The habitat selected 

 was amply moist up to the date that the measurements were made, 

 and during the period in question each species functioned normally 

 at all times. 



As the season advanced, the soil, even to the lower depth of the 

 roots, gradually became so dry as to completely eliminate all the seed 

 ling plants. Redtop, the plant requiring the greatest amount of 

 moisture in the superficial layer, died from drought at some time or 

 other during the first six weeks of growth. Kentucky blue grass, next 



