74 



Development and Activities of Roots of Crop Plants. 



On July 1 no water was available in the surface 6 inches of soil, a week later 

 only 1 or 2 per cent was available from 1 to 3 feet, while by the latter part of 

 the month a deficit occurred to 2 feet and less than 1 per cent was available 

 to 4 feet. Somewhat similar conditions prevailed late in August. Water 

 relations at Burlington were even less favorable for plant growth than those 



TMR50AY FRIDAY. SATURDAY. SUNDAY. 



Fig. 35. — Hygrothermograph records from Lincoln (upper) and Burlington, June, 1921; 

 light lines temperature, heavy lines humidity. 



at Phillipsburg. While the surface foot was well moist during April, May, 

 and early in June, only a small available supply (0 to 5 per cent) occurred in 

 the second and third foot, while at no time during the season was the soil 

 moist below the hardpan layer (about 2.7 feet deep). An available supply 

 of only 1 to 6 per cent was found at all levels above the hardpan throughout 



