SIMPLIFIED ALGORITHM FOR THE RATIONAL APPLICATION OF NITROGEN IN BREAD WHEATS IN THE MEXICAN BAJIO

Abstract

Excessive applications of nitrogenous fertilizer (N) are common in the Bajío, the second productive region of Mexico. The GreenseekerTM sensor determines N requirements, improves its use efficiency, reduces pollution and increases profitability, but the algorithm used to recommend N doses at the stem elongation stage uses values of the Normalized Difference Vegetation Index (NDVI) of an area rich in nitrogen (ARN), whose establishment intensifies work and hinders technology transfer due to the small size of the production units; for this reason, a simplified algorithm that does not use ARN was generated using the biomass estimation index per day (INSEY) estimated with the NDVI of 23 plots fertilized at sowing with doses of N (DFNI) from 0 to 180 kg ha^-1 plus an ARN of 300 kg ha^-1. The validation of the algorithm was in a trial of six varieties of wheat fertilized at sowing with 0, 46, 69, 92, 115 and 138 kg ha^-1 of N and supplemented with the amounts required at the stem elongation stage (FNR) calculated with the algorithm. The gain in yield and the accuracy of recommendations were determined with a similar trial, but without complementary N. The experimental design was randomized complete blocks in split plots, DFNI were placed in the whole plot and varieties in the split plot. The equation DN = 274 - (11458 × NDVI/DDS) was generated, which estimated amounts of N for re-fertilization between 118 and 69 kg ha^-1 to complement the doses of 46 to 138 kg ha^-1 applied at sowing. The average yield was 7.5 t ha^-1, higher than the regional average (5.5 t ha^-1) obtained with up to 350 kg ha^-1 of N.