Additional Evidence on the Applicability of the New Fertilizer-Yield Relation

Abstract

A new fertilizer-yield equation recently discovered by the author was used to describe the relation between the applications of nitrogen-, phosphorus-, potassium-, calcium-, and magnesium-bearing materials and the yields of sugarcane and corn in 34 experiments carried out in various regions of Puerto Rico near Isabela, Gurabo, Patillas, Lajas, and Río Piedras. The equation under study satisfactorily fitted such fertilizer-yield data, even in cases where the fertilizer-yield equation suggested by other workers do not apply. The general applicability of the new fertilizer-yield equation even in cases of certain abnormal data has been noted. From the data studied, it seems that, as concerns the production of sugarcane in soils similar to those used in the above-mentioned experiments, there is more need to keep the available soil nitrogen and magnesium contents as near as possible to their optimum equilibrium values than is true of phosphorus, potassium, and calcium. In corn production the equilibrium of the available nitrogen, phosphorus, and magnesium seems to be more important than that of the available potassium and calcium.