Plate I. — Chahacteh of Vegetation ox Un'i.imbd Plots, 1920. 



Photo. h:i R. L. Coffin. 

 With sulfate of ainiiionia. Vipkl per acre, ?,020 pounds. 





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Photo, by R. L. Coffin. 



With nitrate of soda. Yield per acre, 4,1*>0 pounds. 



