Effects of conventional moldboard and reduced tillage on seasonal variations of direct CO2 and N2O emissions from a loam Haplic Luvisol

Abstract

Greenhouse gases such as N2O and CO2 are formed in microbiological processes of nitrification and denitrification and also governed by microbial decomposition of soil organic matter (SOM) plant residues. A key factors influencing these processes are temperature and soil moisture. Therefore the objectives of this study were to: (1) evaluate the seasonal variations in SOM content, temperature, water-filled pore space (WFPS) and mineral nitrogen content under conventional tillage (CT) and reduced tillage (RT) system, and (2) assess the direct CO2 and N2O emissions associated with the seasonal variations in the soil properties under both tillage systems. An experiment was carried out in a randomized blocks with two different tillage system: CT and RT in a Haplic Luvisol (loamy) covering the growing season of spring barley. Each block included treatments: no mineral fertilizers; mineral fertilizers; mineral fertilizers plus plant residues. Overall, the SOM content and temperatures were insignificantly higher in the plough layers of RT than CT during the entire period of study. Soil moisture content (SMC) and WFPS were insignificantly higher in CT than RT. The application of mineral fertilizers resulted in a significant increase of mean NO3− concentrations only in the plough layers of CT. SMC was a stronger driving factor of mean daily CO2 emissions in all treatments, while variations in soil temperatures and SMC were jointly responsible for changes in mean daily N2O emissions in all the treatments of CT and RT. The postponed highest peaks of mean daily N2O emissions from RT were observed under aerobic soil conditions several days after the heavy rainstorm. The cumulative CO2 and N2O fluxes were insignificantly higher from CT than RT over the entire period of study.