The Scientist on the Farm. 321 



c. Sand: Particles one twenty-fifth to one five-hundredth of an 



inch in diameter. Sand is loose, quick and not sticky. 



d. Gravel: Particles three inches to one twenty-fifth of an inch. 



e. Stone: Three feet down to three inches in diameter. 

 /. Hninus: A corrective of either clay or sand. 



g. Watej- and air: Fill soil pores. 



/;. Remark: The loams consist of the various soil inj?redients in 

 different proportions, and are named accordiny^ly. These 

 are: clay loam, silt loam, sandy loam, gravelly loam, stony 

 loam, and muck loam or humus loam. These terms are use- 

 ful in soil surveys. 



2. Soil Solutes. — Of direct value to crops in food making. 



a. Carbonic acid: Source of carbon in food-making by green 



plants. 



b. Water: Source of hydrogen and oxygen in food making by 



green plants. 



c. The saltpeters arid other nitrates: The only source of nitrogen 



for green plants in food-making. 



d. Gypsum arid other sulfates: The only source of sulfur for 



food-making by green plants. 



e. Phosphate rock and other phosphates: The only source of 



phosphorus for green plants in food-making. 



3. Soil Solutes. — Of indirect value to crops in food making. 



a. Potash compound: Necessary to green plants in sugar produc- 



tion. How used is not known. 



b. Humus: Used as food by nitrogen-fixing and other bacteria. 



Humus is essential to soil fertility. 



c. Iron compound: A necessity in the manufacture of chlorophyll, 



though not a part of it. 



d. Limestone: Neutralizes harmful organic acids. 



e. Water: A uni^'-ersal solvent and a transporting agent. 



/. Silica: Probably useful in protecting the stems of the grasses 

 (the grains) against the attacks of sucking insects. 



g. Common salt: Possibly useful in very small amounts, but in 

 large amounts retards the endosmosis of water. 



SOIL SURVEY MAPS. 



Reports on the soils of Cherokee, Greenwood, Riley and 

 Shawnee counties with large soil maps have been prepared by 

 men from the United States Department of Agriculture in 

 conjunction with men from our Agricultural College. Several 

 other areas have been surveyed; but so far as the writer 

 knows, reports on these areas have not been published. These 

 surveys seem to have been carefully made, but the writer 

 would like to make three suggestions which, if followed, would 

 in his opinion make future survey reports more serviceable. 



21— Sci. Acad.— 2163 



