The work carried out within each work package (WP), together with the associated results and their exploitation and dissemination, is described below:
WP1: Manual chambers were deployed across 50 locations to detect spatial hot spots and temporal hot moments in relation to microbial activities and soil chemical changes. Soil samples were analysed for microbial DNA, RNA, and qPCR to assess the abundance and activity of denitrifying bacteria & archaea. Nitrous oxide emissions were measured using LGR-ICOS laser gas analyser & compared with continuous data from flux gradient micrometeorological instruments. Data analysis involved Lorenz curves, mean relative differences, & standard deviations to identify variations in emissions. Soil temperature & volumetric water content were monitored using copper-constantan thermocouples & time domain reflectometry probes. Analyses were performed using MATLAB and R software. The Variations in microbial processes, quantified through gene abundance and activity indicators, were found to play a critical role in regulating nitrous oxide emissions. These findings advance the understanding of microbially driven greenhouse gas dynamics in agricultural systems. The results have been disseminated through presentations at conferences & seminars, & a manuscript reporting the key outcomes has been finalised.
WP2: Planar optodes were installed at various depths in lysimeter. Soil water samples were collected to monitor changes in mineral N and pH, while automatic chambers continuously monitored soil nitrous oxide fluxes, connected to a trace gas analyser. Data were analysed using R software and ImageJ, establishing correlations between soil management, N cycling, and emissions. Results showed that crop rotation and winter warming influence soil biophysiochemical processes governing nitrous oxide emissions and nitrate leaching. Two manuscripts will be published in scientific journals, focusing on the effects of crop rotation and winter warming on nitrous oxide emissions and nitrate leaching in sandy and clay loam soils, & the influence of diversified crop rotations on nitrous oxide–producing microbial communities during the spring thaw period.
WP3: A field experiment to study the impact of crop rotations and dual nitrification and urease inhibitors on nitrous oxide emissions from cover crop residues. Nitrous oxide fluxes were measured using the flux gradient approach, and data were analysed in MATLAB. Soil mineral N dynamics, temperature, and moisture were continuously monitored, and crop biomass and grain yields were recorded at harvest. The results showed that the addition of cover crops can increase nitrous oxide emissions in diversified crop rotations. However, the use of combined nitrification and urease inhibitors was found to effectively mitigate these increased emissions, reducing nitrous oxide losses to levels comparable to rotations without cover crop incorporation. The results have been published in the scientific journal. Key outcomes were also communicated to a wider audience through a popular Farmtario article and disseminated at international scientific conferences and research seminars.
WP4: I have improved and calibrated the DNDC model by incorporating preferential flow parameters to improve the simulation of soil water content. Scenario analyses were conducted to evaluate the effects of different N application rates and management strategies across multiple soil types, under contrasting climatic conditions. Using 30 years of climate data, the analyses assessed the long-term impacts of N management on environmental losses and crop productivity. A manuscript synthesising the model improvements, calibration and validation, and scenario analysis will be published in the scientific journal. The results have been disseminated through presentations at scientific conferences and research seminars.
