104 ELEMENTAEY AGEICULTUEE 



meal in stone basins with stone pestles. The crooked 

 stick also served to dig the root crops. 



Wearing Out the Soil. Men of those times did not 

 know how to cultivate crops. They knew that weeds 

 injured the crops, but they did not know that it was 

 because the weeds took the plant food, water, and 

 air that their grain needed. When the land failed 

 to bring a good harvest, the farmer concluded that 

 the field needed a rest; so he rested it, or, as we say, 

 let it lie fallow for one year. He did not know 

 what we do to-day — that his land only needed a 

 rotation of .crops, that is, a different crop planted 

 each year, or that barnyard manure would make it 

 fertile again (Fig. 54). 



Jethro TuU. About two hundred years ago there 

 lived in England a landlord named Jethro Tull. He 

 watched his crops closely and soon saw that the 

 fields he worked or tilled the most brought the 

 largest crops. He taught other farmers that tillage 

 was the most important part of farming. He be- 

 lieved that fields would never wear out if they 

 were always cultivated thoroughly. He thought that 

 plants took their food in solid little grains or parti- 

 cles, and the only thing needed was to break up the 

 soil very fine and the plants would eat it as a calf 

 eats bran. We know that Tull was mistaken in 

 thinking that plants take their food in solid form, 

 but he did a great service to his farmer friends and 

 to all the farmers siuise that time by showing them 

 how important tillage is (Figs. 55a and 55b). 



