40 



Development and Activities of Roots of Crop Plants. 



II. INVESTIGATIONS AT LINCOLN, NEBRASKA, IN 



1919 AND 1920. 



The root development of crop plants at Lincoln has been studied for the 

 seasons of 1919 and 1920. Data on the root relations of 4 leguminous crops, 

 4 forage plants, sunflowers, and oats, in both upland and lowland areas, dur- 

 ing 1919, have already been published (Weaver, 1920). During 1920, root 

 studies were continued, with particular reference to the successive stages 

 in the development of oats, wheat, barley, alfalfa, and sweet clover and their 

 correlation with environmental factors. In these experiments White Kherson 

 oats, Marquis Spring wheat, and Manchuria barley were grown. The seed 

 of these and also of alfalfa and white sweet clover were obtained from a 

 local seed company. 



The cropped areas were the same as those used the preceding year. The 

 upland plats were located about 3 miles north of Lincoln, on a broad, level 

 hilltop. The soil is a silt-loam of fine texture, but much more compact than 

 that at Peru. The lowland station was located about a mile south of the 

 former and on the edge of the flood-plain of Salt Creek, in rich alluvial silt- 

 loam. 



Mechanical analyses of the soils are given in table 8, together with the 

 moisture equivalents computed from the mechanical composition by the 

 formula of Alway and Russel (1916 : 842). These data show that both 

 soils are fine-textured, being composed mostly of silt and clay. A study of 

 the table shows that they are remarkably similar. 



Table 8. — Mechanical analyses of soils from Lincoln. 



Depth of sample. 



Coarse 

 gravel. 



Fine 

 gravel. 



Coarse 

 sand. 



Medi- 

 um 

 sand. 



Fine 

 sand. 



Very- 

 fine 

 sand. 



Silt. 



Clay. 



Moisture 

 equiva- 

 lent. 



Upland plats: 



p. ct. 



p. ct. 



p. ct. 



p. ct. 



p. ct. 



p. ct. 



p. ct. 



p. ct. 



p. ct. 



0.0 to 0.5 foot 



0.0 



0.0 



0.3 



0.5 



1.6 



19.8 



48.6 



29.2 



31.4 



0.5 to 1.0 foot 



.0 



.0 



.2 



.6 



1.3 



16.7 



52.4 



28.8 



31.8 



1 to 2 feet 



.0 



.0 



.1 



.2 



0.8 



16.7 



55.6 



26.6 



31.5 



2 to 3 feet 



.0 



.0 



.1 



.1 



0.5 



19.0 



57.9 



22.3 



30.1 



Lowland plats: 





















0.0 to 0.5 foot 



.1 



.4 



2.2 



1.8 



5.0 



25.0 



41.3 



24.3 



27.7 



0.5 to 1.0 foot 



.3 



.7 



2.1 



2.2 



5.0 



25.4 



38.8 



25.8 



27.9 



1 to 2 feet 



.2 



.3 



1.3 



1.5 



3.7 



21.4 



40.8 



31.0 



30.6 



2 to 3 feet 



.0 



.1 



0.4 



0.5 



1.7 



19.2 



43.4 



34.7 



32.9 



Table 9 gives the chemical composition of representative composite sam- 

 ples of soil at various depths from the two areas. A study of the table shows 

 that the soils at the two stations are not strikingly different. It may be 

 noted that the lime-content is about the same in both fields. However, the 

 greater amount of volatile matter and the greater nitrogen-content at all 

 depths indicate more favorable conditions for growth in the lowland plats, 

 and this probably accounts in part for the more rapid growth and better 

 development of the crops in this field. The soil in both fields showed medium 

 acidity in the first foot, slight in the second, very slight in the third, while 

 the fourth foot showed no acidity, but was slightly carbonaceous. 



