Thirty-two% of European soils are thought to suffer soil structural damage by compaction. Temperate agricultural grasslands are particularly vulnerable. Larger vehicles, coupled with extended periods of grazing, and greater soil moisture, result in soil compaction: a component of poor soil health. This reduction in soil health reduces yields and increases emissions of nitrous oxide (N2O) from N application. As grass swards are not tilled regularly, mechanical improvement of structure is restricted. We assessed two non-inversion methods of grassland soil alleviation: mechanical slitting of the surface and shallow soil lifting. These were tested on two contrasting soils (sandy, free draining and silty clay loam, imperfectly drained) for dry matter (DM) yields over three annual silage cuts and emissions of N2O. Alleviation decreased soil bulk density, especially for the clay soil, but gave limited improvement in yield; as the sward lifter reduced the first cut DM yield for both soil types. N2O emissions were enhanced by alleviation, especially, the sandier soil, up to 94% more than the uncompacted control with implications for the potential short-term release of N2O from grassland, (up to 243 kg) associated with improvements to the physical aspects of soil health, for a 150 ha dairy farm.

Straw returning (R) combined with the application of a decomposition agent (RD) can increase crop yield and soil carbon (C) storage. However, the effect of RD on soil nitrous oxide (N2O) emissions in tropical areas remains poorly understood. In this study, an in situ experiment was performed under different water management strategies (long-term flooding or alternate wetting and drying) with the R and RD treatments to evaluate soil N2O emissions and rice yield. The SOC and TN contents were significantly lower under the RD treatment than under the R treatment. The R treatment significantly increased rice yield; however, the yield was further significantly increased under the RD treatment. The soil N2O emissions and yield-scaled N2O emissions were higher under the R treatment than under the no-straw-returning treatment. However, the RD treatment greatly reduced soil N2O emissions and yield-scaled N2O emissions under various water management strategies compared with those under the R treatment. Moreover, yield-scaled N2O emissions were lower in the RD treatment than in the control. The soil N2O emissions and yield-scaled N2O emissions were distinctly higher under alternate wetting and drying than under long-term flooding. Our results indicated that long-term flooding and straw returning with decomposition agents can effectively increase rice yield and reduce soil N2O emissions in tropical areas.

Studies of the impact of nitrification inhibitors (NIs), specifically DMPP and DMPSA, on N2O emissions during hot moments have produced conflicting results regarding their effectiveness after rewetting. This study aimed to clarify the effectiveness of NIs in reducing N2O emissions by assessing residual DMP concentration and its influence on ammonia-oxidizing bacteria (AOB) in two pot experiments using calcareous (Soil C, Calcic Haploxerept) and acidic soils (Soil A, Dystric Xerochrepts). Fertilizer treatments included urea (U), DMPP, and DMPSA. The experiments were divided into Phase I (water application to dry period, 44 days) and Phase II (rewetting from days 101 to 121). In both phases for Soil C, total N2O emissions were reduced by 88% and 90% for DMPP and DMPSA, respectively, compared with U alone. While in Phase I, the efficacy of NIs was linked to the regulation of AOB populations, in Phase II this group was not affected by NIs, suggesting that nitrification may not be the predominant process after rewetting. In Soil A, higher concentrations of DMP from DMPP were maintained compared to Soil C at the end of each phase. Despite this, NIs had no significant effect due to low nitrification rates and limited amoA gene abundance, indicating unfavorable conditions for nitrifiers. The study highlights the need to optimize NIs to reduce N2O emissions and improve nitrogen efficiency, while understanding their interactions with the soil. This knowledge is necessary in order to design fertilization strategies that improve the sustainability of agriculture under climate change.