184 



DRY-FARMING 



the soil solution by the addition of artificial fertilizers 

 enabled the plant to produce dry matter with less 

 water. He further found that if a soil is properly 

 tilled so as to set free plant-food and in that wa}' to 

 enrich the soil solution the water-cost of dry plant 

 substance is decreased. Hellriegxd, in 1883, con- 



FiG. 44. Interior of olive onhard, Sfax, Tunis. Xrjtr' the great tlistances 

 between the trees and the perfectly clean soil culture. 



firmed this law and laid down the law that poor 

 plant nutrition increases the water-cost of every 

 pound of dr}' matter produced. It was about this 

 time that the Rothamsted Experiment Station re- 

 ported that its experiments had shown that during 

 periods of drouth the well-tilled and well-fertilized 

 fields yiekled good crops, while the unfertilized fields 



