Dynamics of N2O in vicinity of plant residues: a microsensor approach

Abstract

AimsPlant residues decomposing within the soil matrix are known to serve as hotspots of N2O production. However, the lack of technical tools for microscale in-situ N2O measurements limits understanding of hotspot functioning. Our aim was to assess performance of microsensor technology for evaluating the temporal patterns of N2O production in immediate vicinity to decomposing plant residues.MethodsWe incorporated intact switchgrass leaves and roots into soil matrix and monitored O2 depletion and N2O production using electrochemical microsensors along with N2O emission from the soil. We also measured residue’s water absorption and b-glucosidase activity on the surface of the residue - the characteristics related to microenvironmental conditions and biological activity near the residue.ResultsN2O production in the vicinity of switchgrass residues began within 0–12 h after the wetting, reached peak at ~0.6 day and decreased by day 2. N2O was higher near leaf than near root residues due to greater leaf N contents and water absorption by the leaves. However, N2O production near the roots started sooner than near the leaves, in part due to high initial enzyme levels on root surfaces.ConclusionElectrochemical microsensor is a useful tool for in-situ micro-scale N2O monitoring in immediate vicinity of soil incorporated plant residues. Monitoring provided valuable information on N2O production near leaves and roots, its temporal dynamic, and the factors affecting it. The N2O production from residues measured by microsensors was consistent with the N2O emission from the whole soil, demonstrating the validity of the microsensors for N2O hotspot studies.