102 ROOT DEVELOPMENT IN THE GRASSLAND FORMATION. 



The roots of both crops reached a maximum depth of 5 feet in the 

 hard clay subsoil, but only relatively few roots penetrated so deeply. 

 Those of the common rye had a working depth of 3.9 feet, while the 

 absorbing level of the "Rosen" variety was about 3.7 feet. The soil 

 was fairly moist to the maximum depth of excavation, about 5.5 feet. 

 The roots were exceedingly well branched to the working depth. In 

 fact, branching is usually better developed in rye than in wheat or oats 

 when growing in the same soil type and under the same conditions of 

 moisture. This is one reason why rye is adapted to drier climates than 

 wheat and will thrive on poorer and sandier soils than any of the other 

 cereals (cf. Miller, 1916, on corn and 

 sorghums). In this connection the 

 work of Nobbe (1869) is interest- 

 ing. He compared, measured, and 

 counted the roots of winter wheat 

 and rye plants 55 days old and grown 

 in soil. He found that the roots of 

 the first to the fourth order num- 

 bered 16,000 in rye and 10,700 for 

 wheat. The combined lengths of 

 these roots measured 118 and 82 

 meters respectively. 



The root system of oats, Avena 

 sativa, was also examined at three 

 different stations at Lincoln. Two 

 of these stations were in the crop 

 plats adj oining the high and low prai- 

 rie stations respectively, while the 

 third was in the experimental fields 

 of the State University farm. 

 White Kherson oats were examined 

 at each place, but the soil types 

 were very different. The crop plats 

 adjoining the low prairie were on 

 rich, black, alluvial soil known as 

 Wabash silt-loam, which was under- 

 laid with a rather tenacious sub- 

 soil of clayey texture. A full de- 

 scription of the mechanical and chemical composition of the soil, 

 together with its water-content through the growing season, is given 

 on pages 140 and 141. 



The oats, following a crop of potatoes, were sowed quite thickly on 

 April 24, after the soil had been plowed to a depth of 4 or 5 inches. On 

 July 8 the oats were quite ripe. The stalks averaged 3 feet in height 

 and the well-filled heads indicated an excellent yield. The deepest 



Fig. 32. — Root system of Avena sativa 

 grown in moist silt-loam soil. 



