Soil nitrogen dynamics under tobacco with different fertilizer management in southern Brazil

Nitrogen (N) is an essential element to the constitution and metabolism of many plant components, being the most effective nutrient for improving yield and quality of tobacco (Nicotiana tabacum L.) plantations. We aimed to quantify potential N losses through leaching and volatilization and consequent tobacco yield under N fertilizer sources/management in southern Brazil. Experiments were conducted under similar conditions in four locations over three cropping seasons: 2013/2014, 2014/2015 and 2015/2016. Treatments were three N sources (urea, Chilean saltpeter and ammonium nitrate) with distinct application methods for urea (incorporated and broadcasted) plus a control (zero). N losses were quantified through ammonia (NH3) volatilization and inorganic N (nitrate and ammonium) movement down the soil profile, by tracking their concentration in soil solution and accumulation in soil layers over the tobacco growing cycles. Tobacco yield and N accumulation in leaves were annually determined. Tobacco yield was positively influenced by N fertilizer application, irrespective of the source/management used. Amongst sources, Chilean saltpeter presented the lowest NH3 emission, being the most effective in maintaining higher inorganic N in soil solution. Expressive volatilization of NH3 was observed under urea in surface application, reaching 16% of loss from fertilizer. Overall, it was detected higher concentration of nitrate and ammonium in the initial tobacco crop phase, between 20 and 50 days after transplanting. Therefore, as a practical recommendation splitting the early tobacco N rates in later applications should be considered to minimize losses through leaching and better synchronize crop demand. (C) 2020 Elsevier B.V. All rights reserved.