Influence of Biogas Slurry and a Nitrification Inhibitor Application in Nitrous Oxide Emissions by Soil

Abstract

As global efforts to combat climate change intensify, agricultural emissions are increasingly scrutinized. Biogas slurry (BS), a by-product of agricultural waste, not only provides essential nutrients for crops but can also elevate soil nitrous oxide (N2O) emissions. This study investigates the immediate and long-term impacts of BS application on N2O emissions, taking into account the frequency of application and evaluating the effectiveness of nitrification inhibitor 3,4-dimethylpyrazole-phosphate (DMPP) in reducing emissions. Through a microcosm incubation experiment with a 108 h robotized incubation-monitoring system, it was found that N2O emissions spiked immediately following a single BS application, with emissions decreasing within 30 days. Repeated BS applications yielded lower cumulative emissions. Elevated N2O emissions were linked to higher soil pH and ammonium (NH4+) levels, along with reduced nitrate (NO3−) concentrations after a single BS application. The combined application of BS and DMPP proved most effective in inhibiting nitrification and cumulative N2O emissions, achieving reductions of 63.0% and 94.6%, respectively. High soil pH, NH4+, and low NO3− were identified as pivotal factors in this effect. These findings highlight the need for mitigation strategies such as dilution or splitting applications to reduce emissions. Integrating BS with DMPP offers a sustainable approach to achieving both agricultural and environmental goals.