NITRATOS EN EL SUELO A LA SIEMBRA O AL MACOLLAJE COMO DIAGNÓSTICO

PABLO BARBIERI; HERNÁN ECHEVERRÍA & HERNÁN SAINZ ROZAS

Ciencia del Suelo

Asociación Argentina de la Ciencia del Suelo

Lugar: Bs As; Año: 2008 vol. 27 p. 41 - 47

0326-3169

ABSTRACT Nitrogen (N) wheat requirements in southeastern Buenos Aires province are determined by soil sampling at pre-planting (0-60 cm). Nevertheless, soil sampling at tillering could be a more precise tool for diagnosing N deficiencies due to N losses during initial stages of growing seasons as a consequence of excessive water in the soil profile. The objective of this study was to validate the methodology of N diagnostics and N application at planting or tillering at the different sites and years insoutheastern Buenos Aires province. An additional objective was to analyze the possibility of estimating NNO3- levels up to 60 cm soil depths using soil N-NO3- contents up to 40 cm. In 6 of 10 sites, applications of N at tillering increased grain yield significantly compared to fertilization at planting. Relative yield (RY) was related to mineral N content (0-60 cm) at planting (r2= 0.73) or tillering (r2= 0.80). Response thresholds for 95% of RY were 152 kg N ha-1 and 126 kgN ha-1 for fertilization at planting or tillering, respectively. Soil N-NO3- content up to a soil depth of 60 cm was highlyassociated with N-NO3- content to the 40 cm depth for both sampling moments (r2= 0.98 and 0.90 for planting and tillering, respectively). Soil N-NO3- content from 0 to 60 cm can be estimated using soil N-NO3- content from 0 to 40 cm. Key words. Wheat, soil N diagnostics, sampling moment, nitrate to 0-40 cm.