Investigations at All Stations. 



83 



and Burlington the cereals, and particularly the oats and wheat, had many 

 dead or injured leaf-tips, probably the result of local drought, coupled with 

 frost injury at the latter station. At all the stations the development of 

 the crops checked well with those in adjoining fields, respectively. 



The precipitation during the period (April 28 to May 20) was 3.8, 2.2, 

 and 0.7 inches going from Lincoln to the western stations, respectively. 

 The available water-content on May 19 to 21 (table 25) occurred in decreasing 

 amounts as one proceeded westward. In the first 2 feet of soil the minimum 

 supply, which was 12 per cent at Lincoln, fell to 10 per cent at PhilUpsburg 



May June 



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Fig. 37. — Average day air-temperatures (heavy lines) and average night 

 temperatures (light lines) at Lincoln (solid lines), and Phil- 

 lipsburg (long broken lines) and Burlington (short broken 

 lines), 1921. 



and 4 per cent at Burlington. At a depth of 2 to 4 feet no water was available 

 at Burlington, about 5 per cent at Phillipsburg, and 15 per cent at Lincoln. 



Soil-temperatures (except for fluctuations in the surface foot) had increased 

 at all stations (table 26) and were more favorable for root development. 

 A continuous record of the temperature at a depth of 3 inches in the prairie 

 sod was obtained at Phillipsburg and Burlington. The average daily tem- 

 perature at PhilUpsburg varied from 55° to 60° F. while at Burlington it 

 was rather consistently 5° colder. The daily range at Burlington (12° to 18° 

 F.) was also somewhat greater than at the former station. The average day 



