Bui. 31, Porto Rico Agr. Expt. Station 
Plate I 
Showing Poor Growth of Coffee in South Field Following Heavy 
Applications of Nitrogen Alone, Plat 42, Upper Left, and Plat 57, 
Lower Right; and Vigorous Development Where to the Same Quan- 
tities of Nitrogen, Potash Has Been Added, Plat 43, Upper Right, 
and Plat 58, Lower Left 
Photographed January, 1922 
