Evaluating carbon sequestration of different alternative management practices in the Netherlands

Purpose: To meet the Paris Agreement targets the Government of the Netherlands aims to sequester 0.14 Mt C per year in clay and sandy soils from 2030 onwards through alternative management practices. Multiple international meta-analyses and modelling studies have been carried out to quantify the soil carbon sequestration potential of alternative management practices. However, the specific impact of such practices for Dutch field conditions have not yet been assessed. In this study, we quantified the potential of a broad range of alternative management practices to sequester carbon in Dutch agricultural clay and sandy soils. Methods: Alternative management practices included altered crop rotations, non-inversion tillage, use of compost and use of animal manure for arable farming and extending pasture age, maize-grass rotation replacing continuous maize cropping, and non-inversion tillage in maize cultivation for livestock farming. Measurements were performed in existing long-term field experiments (LTE’s) comparing treatments of the alternative practices to the standard practices. For some practices like altered rotations and extending pasture age no LTE’s were available. In those cases the comparison between practices was designed by comparing field plots on farmers’ fields based on history of the field and comparable soil conditions. Soil sampling was carried out at the 0-30 cm and 30-60 cm depth layers between 2018-2020 using a standardized protocol including soil density sampling. Results: The variation in carbon sequestration rates appeared to be higher on sandy soil as compared to clay soil. The most promising management practices on clay soil were compost additions (0.4 t C ha-1 year-1), extending pasture age (1.3 t C ha-1 year-1) and non-inversion tillage in maize cultivation (0.7 t C ha-1 year-1). On sandy soils maize-grass rotation significantly increased soil carbon levels (1.8 t C ha-1 year-1) together with liquid manure applications (0.6 t C ha-1 year-1). Conclusion: Our study shows that the potential of alternative management practices under Dutch field conditions to sequester carbon in agricultural soil is largely determined by soil type. In addition, our results show that, based on the investigated management practices, livestock farming has more options to sequester carbon in agricultural soil than arable farming.