Investigations at Burlington, Colorado. 



77 



than at most mixed-prairie stations (Weaver, 1920 : 122) is in agreement with 

 results obtained the preceding year and is probably due to the unusually 

 moist subsoil resulting from 11 inches of excess precipitation during 1919, 

 coupled with rather arid above-ground environment during the growth of 

 the crops. In general, the root habit of the cereals was very similar at Phil- 

 lipsburg and Lincoln, but markedly different from those at Burlington, where 

 the abundance of roots, branching, etc., was much more pronounced in the 

 surface soils 



During July, and again in August, 400 alfalfa plants of average size were 

 carefully selected at each of the stations, cut just below the crown, thoroughly 

 air-dried in the laboratories in Lincoln, and the dry weight obtained. Similar 

 collections of sweet clover were made, each one containing 300 plants (plate 4). 

 The development of the leguminous crops is summarized in table 20, where 



Table 20. — Development of leguminous crops, 1920. 



Crop and station. 



Alfalfa: 



Lincoln 



Phillipsburg . 



Burlington. . 

 Sweet clover: 



Lincoln 



Phillipsbui g . 



Burlington. . 

 Alfalfa: 



Lincoln. 



Phillipsburg . 



Burlington. . 

 Sweet clover: 



Lincoln. . . . 



Phillipsburg 



Burlington. 



Date of 

 cutting. 



July 12 

 July 9 

 July 8 



July 12 

 July 9 

 July 8 



Aug. 9 

 Aug. 4 

 -Aug. 5 



Aug. 9 

 Aug. 4 

 Aug. 5 



Ave. 

 height. 



feet. 

 1.5 

 0.7 

 0.4 



2.0 

 1.3 

 0.4 



1.8 

 1.2 

 0.6 



2.5 

 1.7 

 0.8 



Dry weight of 

 400 av. plants. 



grams. 

 528 

 292 

 122 



2840 

 461 

 213 



739 

 601 

 214 



n,103 

 869 

 323 



Max. 

 depth. 



feet. 

 5.7 

 5.0 



i2.3 



5.5 

 5.7 

 2.8 



5.9 



i2.0 



2.7 



Date of 

 excavation. 



July 24 

 July 10 

 July 7 



July 24 

 July 9 

 July 7 



Aug. 10 



Aug. 25 



Aug. 25 



1 Depth determined by hardpan. 



2 At each station 300 sweet clover plants were taken. 



the data for Lincoln are from the lower crop plats. A study of the table 

 shows that both the height-growth and dry weight, like that of the cereals, 

 correlates directly with available water-content, being greatest at Lincoln 

 and least at Burlington. Root penetration is greater for sweet clover at 

 Phillipsburg, but less for Alfalfa than at Lincoln, while at Burlington the 

 depth of penetration of both is only about half as great. Tap-roots with 

 relatively few short branches characterized the root system at the two less 

 arid stations, but at Burlington the abundance of large, profusely branched 

 laterals above the hardpan was very pronounced. 



