Results from two national field experiment networks with maize and wheat: effects of enhanced efficiency nitrogen fertilizers on crop yields, greenhouse gas emissions, and soil organic carbon sequestration

PERALTA, G,; .RUBIO G.; MA TABOADA; TORIBIO M

Simposio; Global Symposium on Soils or Nutrition; 2022

Our objectives were to answer the following questions: a) what is the impact of different CRNF on crop yields and NUE in maize and wheat?; b) What is the CRNFs impacts on GHG emissions per unit of N applied and per unit of produced grain? and c) What is the potential for offsetting emissions from agricultural soils with the different CRNFs?As expected, N fertilizers significantly increased maize and wheat yields. Between the CRNF sources analysed, the ULC had better performance than urea, since it not only had lower direct and indirect N2O emissions, as well as UI (IPCC 2019), but also had significantly higher crop yields than the other sources. This determined a lower intensity of GHG emissions with ULC. This better yield performance should be attributed to lower N losses and higher NUE. Because of the higher crop yields, and increased C residue inputs to soils, SOC models showed that soils were mostly a carbon sink in maize (93% of experiments), and in wheat (76% of experiments).GHG emissions were decreased by about 15% by CRNF. ULC showed the lower GHG intensity (CO2e per kg grain) across most experiments in maize and wheat. N fertilizers were highly effective to offset GHG emission in maize (93% cases) and to a lesser extent in wheat (76% cases).