148 



Journal of Agricultural Research 



Vol. X, No. 3 



Effect of Layers op Different Soil Types 



In the fifth experiment with soil types, bell jars filled with soil con- 

 taining 14.7 per cent of moisture were used as sources of water supply 

 for mixtures of soil types in glass tubes }i inch in diameter. The bell 

 jars and glass tubes were arranged as in the previous experiments. la 

 the first trial the soil in the tube consisted of a layer of sand followed 

 by a mixture of sand and loam, then loam alone, and finally clay. 



Fig. 2S. — Diagram showing the rate of capillary movement through soil columns composed of layers of 



different types of soils. 



In the second test the order of the soil types was reversed, the clay being 

 nearest the source of supply. A record was kept of the rate of movement 

 in each of these tubes, and the results are presented in figure 28. 



With the soil increasing in fineness from the source of water, the curx'^e 

 shows a considerable and prolonged rise, while with the reverse order 

 of fineness, the rise was very rapid for the first few weeks, but a decided 



