Effect of maintenance liming with olivine, dolomite and calcite on growing-season N2O emissions in an arable soil of SE Norway

 

There is growing evidence that liming reduces the magnitude of N2O emissions in acidic soils. Here we report N2O emissions from a liming experiment with olivine, dolomite and calcite and of maintenance liming with the same materials in clay loam soil at Norwegian University of Life Sciences research farm. The field was bulk limed in 2014 and monitored for N2O fluxes by an autonomous filed flux robot (FFR). Over the course of four years, the fluxes varied but showed a potential of lime as a mitigation tool, with calcareous treatments (dolomite and calcite) displaying a clear decline in N2O emissions compared to unamended plots. To explore the effect of maintenance liming, subplots were maintenance limed and compared with bulk limed controls after sowing the field to winter wheat (Triticum aestivum L.) in summer and fertilizing with 50 kg NPK-N.

Growing-season N2O emissions (June-September) in maintenance limed dolomite plots were on average 26% lower than bulk limed plots and the corresponding reduction in calcite plots was 16%. There was no effect of maintenance liming in the olivine treatment. N2O emissions decreased in the order unlimed control > olivine > dolomite > calcite, covering a pH_CaCl2 range of 4.9 to 6.5.

Our results suggest that maintenance liming, as a component of good agricultural practice, is important to maintain the N2O reducing effect of liming over time. However, the amount of CO2 released by the dissolution of lime should be investigated in order to fully explore the mitigation potential of soil pH management in crop production.