34 Maine Agricultural Experiment Station. 1919. 



A fertilizer for oats should carry ammonia and that phos- 

 phoric acid and potash cannot be profitably applied. 



A fertilizer for potatoes should carry ammonia and some 

 potash while phosphoric acid will give no money return for 

 its use. 



These inferences will be tested with oats on large areas of 

 Caribou loam on Aroostook Farm in 1919; those regarding 

 potash have been tested and found to be true in the series of 

 "no-potash experiments" that have been carried on at Aroos- 

 took Farm for the 4 past seasons; the inferences regarding 

 phosphoric acid will be tested on Aroostook Farm, on 2 other 

 farms in Presque Isle and 2 in Caribou in 1919. In all of these 

 Caribou loam will be the type of soil used. 



Introduction 



Aroostook County, and particularly the part along the 

 Aroostook River, has 2 characteristic soils that are used for 

 cropping. These grade more or less from one into the other 

 but nevertheless they are 2 well marked types. The best and 

 most abundant potato soil, which occurs where the hard wood 

 growth flourished, has been named by the United States De- 

 partment of Agriculture's Bureau of Soils as Caribou loam. 

 This by imperceptable gradations shades off into a dark brown 

 or gray soil where the land was originally covered with black 

 growth (conifers). To this soil the name Washburn loam was 

 given. The principal soil type is the well drained "Caribou 

 loam." This is the great potato soil of Aroostook County. 

 Interspersing this is the poorly drained inferior "Washburn 

 loam." Originally these soils were similar in origin, but through 

 the centuries of plant occupation they have become biologically 

 different. 



One of the fundamental things in field agriculture is a 

 knowledge of the soil that is being worked with. Much has 

 been learned of Caribou loam from the experience of the men 

 who have been cultivating it for a generation. Chemistry, soil 

 physics, soil bacteriology and a study of the fungous organisms 

 also contribute to the knowledge of this soil. But important 

 as these sciences are, they chiefly serve to explain results ob- 

 tained. There is one way — and only one way — to adequately 



