SOILS AND FERTILIZERS 365 



Sandy Loams. Soils containing some humus and clay, but an 

 excess of sand. 



Loams. Soils inclining neither to sand nor clay, and contain- 

 ing some considerable portions of vegetable mold, being very pul- 

 verulent and easily broken up into loose and porous masses. 



Clays. Stiff soils in which the silicate of alumina and other 

 fine mineral particles are present in large quantity. 



Marls. Deposits containing an unusual proportion of carbon- 

 ate of lime, with often some potash or phosphoric acid resulting 

 from the remains of sea animals and plants. 



Alkaline. Soils containing carbonate and sulphate of soda, or 

 an excess of those alkaline and other soluble mineral substances. 



Adobe. A fine grain porous earth of peculiar properties. 



Vegetable. Soils containing much vegetable debris in an ad- 

 vanced state of decomposition. When such matter predominates, 

 or exists in large proportion in a soil, the term tule, peat or muck 

 is applied to it. 



Geest. Soil resulting from the gradual decay of the original 

 rocks. 



Alluvium. Soil deposited by streams. 



Loess. Wind made soil. 



Till. Soil left by melting glaciers. 



Some soils are crumbly or mellow, and when plowed the fur- 

 row slice turns over loose and granular; while in others, especially 

 silty or clayey soils, the plowed ground is likely to be cloddy, and 

 heavy rain causes the soil to run together and bake when dry. The 

 one is in good tilth while the other is not. If the crumbly soil is 

 examined it will be found to be made up of crumbs or granules 

 from the size of timothy seed to that of peas, formed by loosely ce- 

 menting a number of soil particles or a number of smaller granules 

 together. These crumbs vary in size in different soils, and even in 

 the same soil at different seasons. This texture of peculiar granular 

 condition is brought about by natural causes acting upon certain 

 constituents of the soil and not by tillage, although tillage helps to 

 bring about the condition sooner, as when cloddy ground is har- 

 rowed after a shower. The moisture develops a friable condition, 

 and the use of the harrow simply hastens the work of nature. With- 

 out the shower it would have been almost impossible to get the 

 ground into good shape. 



This granulation or crumbly condition is a necessary property 

 for silt and clay soils. A handful of dust from the road looks and 

 feels quite different from a handful of dry mellow soil from a well- 

 managed field. The former is made up largely of incoherent soil 

 particles, while the latter is made up of granules or crumbs of va- 

 rious sizes. Black clay loam, frequently called gumbo, the soil 

 commonly found in low, flat prairies in central Illinois, usually ex- 

 hibits this property, while the brown silt loam of the rolling prairie 

 shows it to a less extent. The heavy clay soils of the river bottoms 

 sometimes go under the name of buckshot land because of their 

 granular character. This property of granulation gives to a soil 



