Effect of agricultural measures on CO2-sequestration, N2O emissions and soil functions

In light of the Paris Climate Agreement, the Dutch government has set mitigation targets for the emission of greenhouse gases (GHGs). One of the targets for the Dutch agricultural sector is to sequester an additional 0.5 Mton CO­₂-equivalents per year on mineral agricultural soils, from 2030 onwards. Additionally, all Dutch agricultural soils should be sustainably managed by then. The research programme Smart Soil Use aims to determine to what extent it is possible to meet these goals. Since 2018, various projects and experiments investigated (sets of) measures or management practices that have the potential to store carbon (C). For 12 agricultural measures, C-sequestration potential was determined based on a combination of long-term field experiments in which soil C has been measured and C-modeling using the RothC model. Additionally, trade-offs of these measures with the GHG nitrous oxide (N₂O) were monitored in the field experiments, using a static flux chamber setup. In addition, various soil parameters from the BLN (Soil Indicators for Dutch Agricultural Soils) were measured to assess the impact on other soil functions. Here, we present an integrative summary of the results, with for each measure, the C-sequestration potential, the possible trade-off with N₂O emissions, and the consequences for soil functions, such as soil fertility and soil biodiversity. Based on the modelling results, it is possible to sequester an estimated 0.9 Mton CO₂ yearly, using a combination of measures and assuming a maximum implementation of 100%. The first results show that certain measures increase N₂O emissions, but that, overall, a possible trade-off to N₂O emissions will not exceed the benefit of C-sequestration on the short term. Based on a qualitative analysis, most of the measures have a positive or neutral effect on soil functions.