Global changes will modify future nutrient availability with implications for grassland biogeochemistry. Soil organic matter (SOM) is central to grasslands for both provision of nutrients and climate mitigation through carbon (C) storage. While we know that C and nitrogen (N) in SOM can be influenced by greater nutrient availability, we lack understanding of nutrient effects on C and N coupling and stability in soil. Different SOM fractions have different functional relevance and mean residence times, i.e., mineral-associated organic matter (MAOM) has a higher mean residence time than particulate organic matter (POM). By separating effects of nutrient supply on the different SOM fractions, we can better evaluate changes in soil C and N coupling and stability and associated mechanisms. To this end, we studied responses of C and N ratios and distributions across POM and MAOM to 6–10 years of N, phosphorus (P), potassium and micronutrients (K+µ), and combined NPK+µ additions at 11 grassland sites spanning 3 continents and globally relevant environmental gradients in climate, plant growth, soil texture, and nutrient availability. We found addition of N and NPK+µ generally reduced C:N in MAOM and POM. However, at low fertility and at warm, sandy sites, nutrient addition promoted higher MAOM and POM C:N, respectively. Addition of NPK+µ also promoted C storage in POM relative to MAOM, and this was consistent across sites. Our results suggest that addition of macro- and micronutrients consistently decrease SOM stabilization, whereas responses of soil C:N stoichiometry were contingent on SOM fraction and environmental conditions.
|Number of pages||18|
|State||Published - Jul 2022|
Bibliographical noteFunding Information:
We thank Aaron Prairie for his assistance in the lab and the Nutrient Network organizers and participants for being willing to share their data, soils, and ideas. We especially thank Brooke Osbourne, Sumanta Bagchi, Sally Power, and Adrienne Keller for their helpful comments on earlier versions of this manuscript. This work was generated using data from the Nutrient Network ( http://www.nutnet.org ) experiment, funded at the site-scale by individual researchers. Coordination and data management have been supported by funding to E. Borer and E. Seabloom from the National Science Foundation Research Coordination Network (NSF-DEB-1042132) and Long Term Ecological Research (NSF-DEB-1234162 and NSF-DEB-1831944 to Cedar Creek LTER) programs, and the Institute on the Environment (DG-0001-13). We also thank the Minnesota Supercomputer Institute for hosting project data and the Institute on the Environment for hosting Network meetings. Soil analyses were supported, in part, by USDA-ARS Grant 58-3098-7-007 to ETB.
This material is based upon work supported by the National Science Foundation Graduate Research Fellowship Program under Grant No. #1650114. This work has benefited from technical and human resources provided by CEREEP-Ecotron IleDeFrance (CNRS/ENS UMS 3194) as well as financial support from the Regional Council of Ile-de-France under the DIM Program R2DS bearing the reference I-05-098/R. It has received support under the program “Investissements d'Avenir” launched by the French government and implemented by ANR with the reference ANR-11-INBS-0001 AnaEE France and ANR-10-IDEX-0001-02 PSL.
© 2022, The Author(s), under exclusive licence to Springer Nature Switzerland AG.
- Mineral-associated organic matter
- Nutrient addition
- Nutrient network (NutNet)
- Particulate organic matter
- Soil organic matter
ASJC Scopus subject areas
- Environmental Chemistry
- Water Science and Technology
- Earth-Surface Processes