Nitrous oxide mitigation potential of reduced tillage and N input in durum wheat in the Mediterranean

Abstract

In Italy, managed soils account for about 50% of annual national emissions of nitrous oxide (N2O), thus the effect of agricultural practices on N2O emissions must be studied in order to develop mitigation strategies. Soil N2O emissions were measured in two field campaigns (2013–2014 and 2014–2015) on durum wheat in a Mediterranean environment to test the mitigation potential of reduced tillage and nitrogen (N) fertilization rate. N2O emissions were measured with a fully-transportable instrument developed during the project LIFE + IPNOA “Improved flux Prototypes for N2O emission reduction from Agriculture” and equipped with an infrared laser detector. Reducing tillage from ploughing to minimum tillage had no effect on average daily N2O flux, while decreasing the N rate from 170 to 110 kg N ha−1 reduced the average daily N2O flux, without negatively affecting the grain yield. Furthermore, N2O daily flux were positively correlated with soil water filled pore space, NO3-N, and NH4-N concentrations, and they were largely variable between the two field campaigns as a result of different environmental and management conditions (i.e.: rainfall, different amount of crop residues incorporated in soil). Overall, the innovative fully-transportable instrument performed well in the field and allowed us to conclude that decreasing the N fertilizer rate was a valuable option to mitigate N2O emissions without negative effects on wheat productivity.