ALFALFA ROOT STUDIES. 



11 



The analyses showed a high percentage of lime, especially at a 

 depth of 1 to 5 feet. The surface foot is a fairly open black silty clay 

 loam. At a depth of 1 to 4 feet it consists of a high percentage of 

 fine soil particles and is fairly compact. A silty loam of a soft, shaly 

 nature occurs at a depth of 4 to 5 feet. From 5 to 10 feet the soil is 

 a clay that is apparently easily penetrated by alfalfa roots. 



Investigations indicate that the type of root growth is pretty defi- 

 nitely determined during the first few months, and for this reason 

 a summary of temperature and precipitation records is presented as 

 indicating in a general way the moisture available to the plant 

 (Table 4). 



Table 4. 



-Suinmary of precipitation and temperature record'^ at Redfield, 

 S. Dak:, from April, 1916, to March, 1917. 



Items of comparison. 



Growing season, 1916. 



Fall conditions, 

 1916. 



Winter conditions, 

 1916-17. 





Apr. 



May. 



June. 



July. 



Aug. 



Sept. 



Oct. 



Nov. 



Dec. 



Jan. 



Feb. 



Mar. 



Total precipitation, inches . . 

 Departure from normal, 



1.11 



-.65 

 43 



-1.7 



5.13 



+2.22 

 55.6 







3.56 



+.82 

 62.4 



-3.2 



2.01 



-.95 



78.8 



+ 8.5 



5.19 



+1.97 

 70 



.6 



1.42 



-.45 

 58.2 



-1 



0.55 



-.8 

 43.8 



3 



T 



-0.4 

 30.9 



— . 5 



2.13 



+1.75 

 7.8 



-9.9 



2.38 



+2.09 

 5 



-7 



0.8 



+,37 

 4 



-8.4 



2.25 

 +1.6 



Average temperature, °F... 

 Departure from normal, 



23.9 

 -5.3 



Total precipitation, inches. . 



Departure from normal, 



inches 



17.00 

 +3.41 



1.97 

 -1.65 



7.55 

 +5.81 



These data show that the season was favorable for alfalfa growth- 

 There was an abundance of rainfall and cool weather in early spring 

 and as late as early July. Drought then became gradually more 

 pronounced, and unusually high temperatures prevailed until the 

 middle of August, when rains occurred, resulting in late summer 

 and fall growth. It would appear that conditions were favorable 

 for a well-established root system in early spring and during tha 

 summer. 



DIFFICULTIES ENCOUNTERED IN GETTING COMPARABLE DATA. 



The chief difficulty encountered in obtaining comparable data on 

 root systems in old fields of the less hardy alfalfa varieties and 

 strains under the more severe environmental conditions is in making 

 l)roper allowance for the doubtless accentuated growth of the sur- 

 viving plants. The more susceptible plants having been winter- 

 killed, the data obtained are from the more hardy individuals that 

 have been given more room, permitting a greater root growth. In 

 these studies at Eedfield it was recognized that this thinning of 

 stands and its effect on root growth was a factor that must be taken 



