Soil Fertility and Its Preservation 49 



References 



"Leguminous Crops for Green Manuring." Farmers' Bulletin 278. 

 "Renovation of Worn-out Soils." Farmers' Bulletin 245. 

 "Soil Conservation." Farmers' Bulletin 406. 

 "A Simple Way to Increase Crop Yield." Farmers' Bulletin 924. 



