ChileanJAR

The efficiency offertilizer nitrogen is analysed in a set of31 trials on wheat, made in "trumao" soil (Andept) in the VIII Region of Chile. When maximum increments of yield are high the respor..se curves tend to follow the "two rectes" model (Iaw of the minimum), the first part of the curve reaching an efficiency of absortion near a 100%. When maximum increment is lower, the efficiences are also lower and some ofthe response curves tend to follow the "decreasing increments" model. It is sugested that, in order to diagnose the probable effect of the nitrogan fertilizer, an estimation of maximum increment in relation to rates of application, should be useful. Efficiency is a function of these two parameters and is much variable; so it is not advisable to estimate an average efficiency to diagnose the effect of fertilizer nitrogen.