_"Population must increase rapidly, more rapidly than in former
times, and ere long the most valuable of all arts will be the art of
deriving a comfortable subsistence from the smallest area of
soil."--Lincoln._


_"It is not the land itself that constitutes the farmer's wealth,
but it is in the constituents of the soil, which serve for the
nutrition of plants, that this wealth truly consists."--Liebig._






CONTENTS





CHAPTER I: What Goes To Make Up Permanent Fertility

CHAPTER II: The Nitrogen Problem And Its Economical Solution

CHAPTER III: Phosphorus: Thke Master Key To Permanent Agriculture