Sustainable management of nitrogen in oats based on stability parameters
ABSTRACT. The productive performance of oats depends on proper management of nitrogen, a highly mobile element and of reduced efficiency in unfavorable cultivation conditions, generating productivity reduction with environmental pollution. This study aimed to find the most efficient and sustainable management of nitrogen in oats based on the nutrient dose at sowing and coverage with the timing of application, considering the main cereal succession systems in Brazil during favorable and unfavorable agricultural years, through parameters that scale performance and adaptability and stability. The experiment was conducted in 2015, 2016 and 2017, in a region of commercial oat cultivation, in the municipality of Augusto Pestana, RS, Brazil. The experimental design was randomized blocks with four replications, in a 4 x 4 factorial model, for four nitrogen rates at sowing (0, 10, 30 and 60 kg ha-1), changing the coverage rate by the total supplied of 70 and 100 kg ha-1 (recommended doses for oats) in a soybean/oat and corn/oat succession system, respectively, with the expectation of a grain yield of 4000 kg ha-1, with the supply in topdress, considering four application times (0, 10, 30 and 60 days after emergence). Regardless of the crop year condition, in the soybean/oat system, the highest nitrogen use efficiency with adaptability and stability for biomass and grain productivity occured in the condition of absence of nitrogen at sowing with the total dose in coverage at 10 and 30 days after emergence. In the corn/oat system, the highest yield efficiency with adaptability and stability was in the combination of the absence of nitrogen at sowing with the total coverage dose at 10 days after emergence.