8 THE CULTURE OF FARM CROPS. 



a great measure by the qualities and characters of differ- 

 ent soils; by temperature, moisture, the action of the var- 

 ious manures and fertilizers not only upon the soil and the 

 crops, but upon each other the habits of the plants, and 

 the vicissitudes of the season. But when the farmer has a 

 sufficient knowledge of these and of the laws which con- 

 trol their action, he is able to guide himself through the 

 labyrinth, just as the sailor steers his ship safely among 

 the rocks and shoals which environ his desired port, by the 

 aid of the chart which lies before him, and his knowledge 

 of the currents which sweep about them. For a farmer to 

 succeed, and grow large crops, without this knowledge of 

 his art, is as impossible as for the sailor to reach his port in 

 darkness, without a compass or a chart, and wholly ignor- 

 ant of his bearings, and the obstacles in his way. That so 

 few farmers wholly fail in their business is a proof not to 

 the contrary of this, but to the rich rewards which the pro- 

 lific soil offers to man's labor and industry, and of which a 

 moderate share only is sufficient for all his needs; but the 

 whole of which brings competence and wealth to the most 

 skillful and studious farmers. 



It is about forty years since agricultural knowledge took 

 a scientific turn, and students began to search for the caus- 

 es of the results which they reached by the slow process of 

 a life long practical service in the field. Then a young 

 man had to learn slowly, day by day, and year by year, 

 often waiting many years to verify, through repeated con- 

 tradictions, any facts which he learned by the closest ob- 

 servation. All the gathered lore of the most successful 

 farmers was then comprised in a very few books, and some 

 popular beliefs, current only verbally, and handed from 

 one to another amid dispute and contradiction The old 

 writers upon agricultural topics merely repeal what they 

 learned from the results of their practice; they wrote of 

 manures from what they had seen of the results of their 

 use; but they had no conception of the fact that manures 

 supplied the cropt with certain elements which were ab- 

 sorbed into their substance and became a part of them. 



