July i6, 1917 Movement and Distribution of Moisture in Soil 115 



Effect of Manure 



Whitney (30) showed that manure lowers the surface tension of the 

 water near the surface so that the moisture of the upper soil moves into 

 the lower layers where the surface tension is greater. The same author- 

 ity (31) later concluded that the urine in the manure has a tendency to 

 deflocculate the soil particles, thereby preventing the loss of moisture 

 by downward movement. Experiments in the field and in cylinders by 

 King (16) indicate that manure has considerable influence in increasing 

 the water content of the soil, even down to a depth of 4 feet, and that this 

 influence is still exerted a year after manuring. He (17) later states that 

 the upper 3 feet of manured fallow land will contain much more moisture 

 than corresponding depths of unmanured soil. He also shows that 

 manure tends to decrease the water content of the second 3 feet in depth. 

 Wetting the surface of sand with liquid leached from manure reduced 

 the capillary rise by 16 inches and the rate of evaporation from the 

 surface by 49.6 per cent. Snyder (28) found that manuring increased the 

 soil moisture during a period of drought. 



Effect of Cultural Methods 



King's investigations (16) indicate that "thorough cultivation keeps 

 the soil below the surface foot cooler, thereby materially increasing the 

 capillary power. The capillary force being stronger, the soil moisture 

 is moved upward faster and through longer distances." He (18) also 

 found the soil below a 3-inch cultivation to be more moist than that 

 below a 1.5-inch cultivation, although the third and fourth feet showed 

 reversed results. Experiments by Chilcott and Holm (9) confirm 

 King's results. King's laboratory experiments (22) show a i-inch 

 cultivation to be the most effective for checking evaporation. 



Field investigations by Kedzie (12) indicate that to a depth of 16 

 inches cultivated plots had 3 per cent more moisture than naked fallow, 

 and that during a period of drought the former actually gained 2 per 

 cent of moisture in the top foot. 



Late in the season Hays and Smith (10) found the cultivated plots had 

 no more moisture than the uncultivated fallow. The soil under straw 

 mulches 4 inches deep contained 5 per cent more moisture than bare 

 fallow. Cardon (8) obser\'ed no advantage in deep plowing or subsoiling 

 over shallow plowing, so far as moisture conservation was concerned. 

 Cultivated fall-plowed fallow maintained practically the same water 

 content throughout the season, while in fall-plowed uncultivated plots 

 w^ater rapidly decreased, owing to winds. Spring-plowed cultivated fallow 

 showed no difference in water content when compared with uncultivated 

 spring-plowed plots in which the weeds were killed by spring plowing. 



The work of Burr (7) showed that the effectiveness of summer tillage 

 depended on the presence or absence of a growing crop, and weeds cause 



