APPLICATION OF SCIENCE TO PLANT CULTURE. 81 



drought and use only the normal, we find that the potato has 

 responded bounteously to all these substances. They bring out 

 the differences in the feeding capacity of corn and potatoes. 



If we estimate the average yield of corn, potatoes, and oats at 

 100, how much increase shall we have if we add 24, 48, or 72 lbs. 

 of nitrogen? Corn rises from 100 to 111 with 24 lbs. ; 112 with 

 48 lbs. ; and 115 with 72 lbs ; potatoes to 127, 138, and 127 ; and 

 oats to J54, 166, and 171, but the number of experiments made is 

 not sufficient for a decisive test. Corn generall}' makes little 

 response to nitrogen, but more to mineral fertilizers, having in 

 this respect more analogy with legumes. Potatoes have less 

 capacity than corn in gathering food and want a pretty good 

 supply of readily digestible food. 



I make a digression here to say that this subject is a hobby 

 with me. The problems which I have indicated may be studied 

 outside the laboratory and greenhouse. Experiments by farmers 

 are very useful. The question whether the experiments of practi- 

 cal farmers have any scientific value ma}^ be answered by the 

 statement that the results of the experiments of Connecticut farm- 

 ers have been published in Germany (where they do not gener- 

 ally give us an}' more credit than we deserve), and also in France. 



Few experiments, except those of Lawes and Gilbert, have been 

 so correctly carried out as those of William Bartholemew and 

 Charles Fairchild, in Connecticut. The former attended the meet- 

 ing of the Connecticut Board of Agriculture ten years ago and no 

 man in the State could have given such v iluable results as he did 

 in a paper which occupied half an hour in the reading. Men who 

 do this kind of work are light-houses, and the time is ripe for many 

 such experimenters. 



Some time since, in writing to Mr. Bartholemew concerning 

 some of the details of his reports, I took occasion to ask if he 

 would state in what ways, and to what extent the large amount 

 of experimental work he has done has been of actual benefit to him 

 as a farmer. He answered as follows : 



" In reply to your question I will say that I have learned to 

 place great confidence in commercial fertilizers when properly 

 used, as furnishing the most reliable and economical materials for 

 increasing my crops. 



" I have learned that the effects of the different substances 

 used, although varying much from each other, are nearly identi- 

 6 



