• PRESENT METHODS OF TEACHING SOILS. 229 



Attention is given to the biology of tlie soil which concerns bacteria 

 and mold life found therein and the functions of these in transforming 

 the store of nitrogen in the soil and probably also the mineral foods into 

 soluble form for the use of the higher plants. 



Soil moisture, soil air, and soil temperature are taken up in order and 

 studied under the general heads : 



(1.) Importance to crops and the changes above referred to. 



(2.) The ideal conditions, and 



(3.) The means by which the farmer may modify or control them. 



The third head naturally leads to the study of farm implements and 

 the art of their construction and use and also to the study of the theory 

 and practice of farm drainage. 



Fortunately we now have a few^ very good texts upon soils as we take 

 them up during this term which we are able to supplement with labora- 

 tory and field practice. 



A portion of the sophomore fall term is given to the study in the labor- 

 atory, of air movements and water movements in the soil, to the deter- 

 mination of the moisture content of soils and to the mechanical separa- 

 tion of a sample of soil into its sand, silt, clay, and organic constituents. 



The work thus far outlined is required of all agricultural students. 

 Any further work he may take is made up of what it may appear para- 

 doxical to call required electives. In the winter term of the junior year, 

 the student elects between horticulture and agriculture. Should he 

 elect agriculture, he plans to specialize in soils and crops or live stock 

 or dairying. If his election be soils or soils and crops, then during the 

 spring term of the junior year, he devotes ten hours per week to carrying 

 out some practical experiment planned during the winter terih, along 

 some line of soil or crop work, as for example, to determine the amount 

 of moisture taken from soils by a crop of weeds or the effect of manures 

 upon soil temperature. 



Eleven weeks of the fall term of the senior year are devoted to labora- 

 tory studies of soils. Four to six samples of soils are given to the 

 student of which he is to determine the specific gravity, apparent spe- 

 cific gravity, least pore space, waterholding power — capillar}^ and hy- 

 groscopic, and the effective size of soil grain with the theor}^ of the 

 methods, to classify and compare the several values and discover, if 

 possible, any existing relations. 



The electrical method and its theory for determining the soluble salts 

 in soils is studied and the apparatus operated. 



During the winter term of twelve weeks, each student carries on some 

 line of investigation, giving ten hours per Aveek to the Avork. This work 

 is written up in the form of a thesis. 



In the spring term soil thermometry, evaporimitry, and the natural 

 pore space of soil is studied and if any time is left some problems in soil 

 mathematics, such as the estimation of the total surface of unit volume 

 of soil and some of the theoretical values and actual values compared. 



While the work of the senior year possesses no small value for the 

 young man returning to the farm, it is planned esyiecially with a view 

 to better equiyjping him to take uy) the work of instruction or investiga- 

 tion. The demand for young men for these lines of work at the present 

 time is very great. 



