Are gaseous nitrogen losses affected by the fertilizer type and rate in maize?

Abstract

Nitrogen (N) management practices have the potential to reduce nitrous oxide (N2O) emissions and ammonia (NH3) volatilization while enhancing maize (Zea mays L.) productivity. However, the specific effect of N rate and source remains unclear. This study aimed to evaluate, during the maize growing season, the effect of both N rate and source on i) gaseous losses through NH3 volatilization and N2O emissions and ii) agronomic traits such as grain yield and N uptake (Nupt). Four experiments were conducted in the humid temperate region of Argentina between 2020 and 2022. Treatments consisted of four N rates, between 0 and 200 kg N ha−1 combined with four N sources [urea, urea with urease inhibitor (UUI), urea with nitrification inhibitor (UNI), and calcium ammonium nitrate (CAN)]. We observed a significant response to N fertilization on grain yield with increases from 20 % to 64 %. However, no differences between N sources were determined. CAN presented the greatest Nupt, which was up to 27 % higher than urea-based N sources. NH3 volatilization was the major N loss process with urea exhibiting the highest values. UUI and CAN significantly reduced NH3 volatilization in comparison to urea. CAN showed the highest N2O emissions, losing up to 1.5 % of the applied N. UNI significantly reduced N2O emissions by 50 %. Emission factors for both NH3 and N2O were consistently lower than the default values suggested by the IPCC guidelines. In conclusion, N sources such as UUI and UNI lead to achieve high grain yields with a low environmental impact.