Oat productivity by root and foliar nitrogen uptake in cropping systems

Abstract

Urea is the standard source of nitrogen for plants, yet it is very unstable, causing losses and environmental pollution. The objective of this study is to validate the technology of spraying liquid source N-Top® of nitrogen for foliar uptake, considering the main oat crops systems in southern Brazil under different agricultural year conditions. The study was developed in 2016, 2017, and 2018, in the city of Augusto Pestana, RS, Brazil, in system soybean/oat and maize/oat. In each system, two experiments were conducted, one for quantifying the biomass rate and the other for the estimation of grain yield. In the four experiments, the design of the randomized block was used with four repetitions in factorial 2×4, for 2 nitrogen sources (liquid and urea) with 4 doses of the nutrient (0, 30, 60, and 120 kg ha-1), respectively. The urea source with 45% of nitrogen for root absorption and the liquid with 28% (N-Top®), via foliar absorption, were applied at the phenological stage of the fourth expanded leaf. In corn/oat system, increasing the dose of nitrogen from urea and liquid sources promotes linear behavior in the expression of grain yield, with similar values of angular coefficient. In the soybean/oat system in the average of the agricultural years, the dose of 78 kg ha-1 of nitrogen, promotes grain yield around 3000 kg ha-1, regardless of the nutrient source. N-top® liquid source nitrogen validation is confirmed, however the acquisition cost may make the recommendation unfeasible