242 Bacteria in Relation to Country Life 



also the moisture, is needed. Hence, in the improvement 

 of light soils, green-manures have played, in the past, and 

 are playing today, a prominent r61e. The green-manures 

 are made here to supply the humus, the nitrogen, and, 

 indirectly, the moisture, to the money crops. Thousands 

 of acres in Germany, France and Belgium, and many 

 thousands of acres in the eastern United States have 

 been brought to a high state of cultivation by the use 

 of mineral fertilizers and green-manures alone without 

 the introduction of much organic material from without. 



The practice of green-manuring, as it has been de- 

 veloped on sandy soils, owes much to the work of Schultz, 

 at Lupitz, Germany. Starting in 1855 on an extremely 

 poor, coarse-grained, sandy soil, he gradually improved 

 it by the use of lime, phosphoric acid and potash in con- 

 nection with such green-manuring crops as lupins, 

 seradella and field-peas, until he could produce three 

 hundred to four hundred bushels of potatoes per acre. 

 He showed that proper mixtures of several legumes may 

 yield more nitrogen and organic matter than any single 

 legume, because of the proportionately slighter injury 

 from insect pests and fungous diseases. He showed that 

 lupins and seradella, the most valuable green-manuring 

 crops for his soil, but very readily injured by even mod- 

 erate amounts of lime, could be made to grow vigorouslj^ 

 in spite of the lime, provided, liberal amounts of kainit 

 were added to the soil. 



We owe much to him for information concerning the 

 time and manner of seeding and harvesting the amounts 

 of potash and phosphoric acid to be used and the manner 

 of their application. We are also indebted to him for 



