A novel N fertilizer to improve N use efficiency by sugarcane

Abstract

The low nitrogen use efficiency (NUE) by sugarcane, coupled with the nitrogen (N) losses in the system, challenges the sustainability of biofuel production. Recent studies showed response of sugarcane to molybdenum (Mo), which may be associated with the improvement of NUE, since Mo is constituent of the enzymes nitrogenase and nitrate reductase. The addition of Mo in sugarcane fertilization will be officially recommended in the State of São Paulo, but large-scale adoption rely on viable strategies of application. One strategy is the addition of Mo in N fertilizers, by coating the granules or incorporation the sources of Mo to the granules. The hypothesis of this study is that the addition of Mo to N fertilizer will increase NUE by sugarcrane. The objective is to study the effect of addition of soluble and insoluble source of Mo to N fertilizers, both in quality of fertilizers, as well as N metabolism and NUE by sugarcane. Regular N fertilizers (urea and urea with N-(n-butyl) thiophosphoric triamide (NBPT)) will be coated with a soluble (sodium molibdate) and an insoluble (molibdenium trioxide - nanomaterial) source of Mo. Molibdenium rates will vary from 0 to 1,200 g ha-1 for the supply of 100 kg ha-1 N. The study will be divided into three phases; i) chemical and physical characterization of fertilizers; ii) measurement of ammonia losses by volatilization and iii) measurement of N metabolism and NUE by sugarcane using 15N isotope under controlled conditions. It is expected that with the results of this project the development of a nitrogen fertilizer that presents lower losses of ammonia by volatilization, that be more utilized by the plant, reflecting in greater NUE and, finally, that can be produced in the future by companies of fertilizers. (AU)