APPLICATION OF SCIENCE TO PLANT CULTURE. 77 



fonnulse for different crops, is to supply nitrogen, phosphoric acid, 

 and potash. 



12. These materials are expensive, but the right ones in the 

 right places are nevertheless very profitable. But the same fertili- 

 zers in other cases may bring little or no return. 



13. It is not good economy to pay high prices for materials 

 which our soils themselves may furnish, but it is good economy to 

 suppl}' the lacking ones in the cheapest way. Farmers cannot 

 afford to use commercial fertilizers at random. No more can they 

 afford to have their crops fail when a small outlay for the proper 

 fertilizer would bring a bountiful harvest. And it is time that 

 the}' understood these facts, the reasons, and how to make use of 

 them. 



14. The only way to find out what our soils want is to study 

 them by careful observation and experiments. Success in farming, 

 as in other business, requires the use of brains. 



The bulk of plant food is obtained from the air ; the mineral 

 ingredients of the plant — the lime, potash, phosphoric acid, etc., 

 entirely from the soil. One of the much disputed questions is as 

 to the source of the nitrogen which enters into the composition of 

 plants, of which Professor Caldwell spoke in his lectures before 

 this Society in 1885 and 1886. 



In removing plants from the soil we remove the substances 

 which the plants have taken from the soil. In experiments made 

 according to directions sent out by myself, strips of land were 

 manured with nitrogeneous fertilizers, phosphate, and potash, these 

 materials being applied singly, two by two, and all three together. 

 The plan was based on the idea that these are most frequently want- 

 ing. Three hundred reports of such experiments were received. 



Different soils vary in their capacity to furnish plant food, 

 just as different plants var}' in their capacity to avail themselves 

 of food in the soil. Near Middletown, Conn., on one farm phos- 

 phate and nitrogen have little effect while potash is very effectual. 

 In another direction potash has very little effect, but phosphate 

 has ; in other cases combinations of several ingredients are 

 necessary. 



Soils vary greatly in regard to their needs. Hundreds of ex- 

 periments show that the ingredients most often lacking in soils 

 east of the Mississippi are first phosphate, next nitrogen, and then 



