HISTORICAL AND INTRODUCTORY 

 Table I. — Statistics of a Rotation. Boussingault (46). 



13 



1000 kilograms per hectare = 16 cwt. per acre. 



Table II. — Nitrogen Statisiics of Various Rotations. 

 Boussingault (46). 



! Catch crop, i.e. taken in autumn after the wheat. 



^ This crop does not belong to the leguminosae, but it is possible that the 

 nitrogen came from the soil, and that impoverishment was going on. 



