Soils 53 



the bottoms in water and observe what happens when the moisture 

 reaches the fine soil. Of what use is a soil mulch? 



5. Influence of lime on soil structure. Make four wooden molds 

 one inch by one inch by four inches. Fit a layer of cheese-cloth into 

 each allowing an inch or so to stick out from the sides. Weigh out four 

 one hundred-gram lots of dry clay soil. To one lot add one gram of 

 caustic lime ; to a second lot, five grams ; to a third lot, ten grams ; add 

 no lime to the fourth. Mix the lime and the clay. To each sample 

 add just enough water to make the soil plastic and press the four lots 

 of soil into the four molds. Remove each lot from the mold, being 

 careful to retain the shape. As soon as you take them from the mold, 

 mark a number on each brick to designate it. Put the bricks away to 

 dry. When thoroughly dry, break them into pieces and observe the 

 difference in the ease of breaking. What effect does the application of 

 lime have on the structure of a clay soil? 



6. Air in soil. Place some soil in a tumbler and pour water on it 

 until a small quantity stands over the surface. Notice the bubbles 

 passing through the water. These are bubbles of air caused by the 

 water displacing the air in the soil. Get two tin cans of the same size. 

 Punch holes in the bottom of one and not in the other. Put soil in the 

 cans to within an inch of the top and plant six grains of wheat in each 

 can. Keep the soil in one can saturated with water and in the other 

 one moist, but not too wet. The seeds will not sprout in the very 

 wet soil. Why is this ? 



Saturate the soil in a tumbler in which a healthy plant is growing. 

 Keep the soil wet. Observe results. What is the condition of the 

 soil? What does it lack that is needed by a growing plant? 



REFERENCES 



Bailey, L. H., Cyclopedia of American Agriculture, Vol. VI, pp. 320- 



353. The Macmillan Co. 



Snyder, Harry, Soils and Fertilizer. The Macmillan Co. 

 Lyon, Fippin, and Buckman, Soils, their Properties and Management. 



The Macmillan Co. 



Lyon, T. L., Soils and Fertilizers. The Macmillan Co. 

 Burkett, C. W., Soils. Orange Judd Co. 

 King, F. H., The Soil. The Macmillan Co. 



Hopkins, C. G., Soil Fertility and Permanent Agriculture. Ginn & Co. 

 Fletcher, S. W., Softs. Doubleday, Page & Co. 

 Hall, A. D., The Soil. Dutton and Co. ' 

 Whiting, A. L., Soil Biology Manual. Wiley and Sons. 



