ABSTRACT
This chapter presents a case study describing the dynamics of nitrogenous fertilizers in the region, especially in view of the fact that agronomical and hydrologic local characteristics favour the processes affecting the adequate handling of nitrogen. Initially, a study was carried out to collate existing information on the agricultural practices performed in the region known as ‘Bajio’ in the state of Guanajuato, México, over the last 30 years. The information gathered included fertilizer usage, crop rotation systems, yields, organic matter content of soils and agricultural handling practices. In this agricultural region, high percentages of ammonium fertilizers and urea are employed; therefore the volatilization of ammonia was determined using the technique of incubation chambers. The results obtained show that the rates of ammonification-nitrification-immobilization depend to a large extent upon the chemical composition of the residues, particularly the type of carbon compound and the carbon/nitrogen ratio.
