Contents lists available at ScienceDirect Geoderma journal homepage: www.elsevier.com/locate/geoderma Environmental drivers and stoichiometric constraints on enzyme activities in soils from rhizosphere to continental scale Svenja C. Stock a, ⁎ , Moritz Köster b , Michaela A. Dippold b , Francisco Nájera c , Francisco Matus c , Carolina Merino c , Jens Boy d , Sandra Spielvogel e , Anna Gorbushina f , Yakov Kuzyakov a,g,h a Soil Science of Temperate Ecosystems, University of Göttingen, Göttingen, Germany b Biogeochemistry of Agroecosystems, University of Göttingen, Göttingen, Germany c Departamento de Ciencias Químicas y Recursos Naturales, Universidad de La Frontera, Temuco, Chile d Institute of Soil Science, Leibniz University Hannover, Hannover, Germany e Soil Science, University of Kiel, Kiel, Germany f Department Materials and Environment, Federal Institute for Material Research and Testing, Berlin, Germany g Institute of Physicochemical and Biological Problems in Soil Science, Russian Academy of Sciences, 142290 Pushchino, Russia h Agro-Technology Institute, RUDN University, Moscow, Russia ARTICLEINFO Handling Editor: Junhong Bai Keywords: Extracellular enzymes Stoichiometric homeostasis Rhizosphere efect Nutrient acquisition Multi-scale study ABSTRACT Microbial activity and functioning in soils are strongly limited by carbon (C) availability, of which a great proportion is released by living roots. Rhizodeposition and especially root exudates stimulate microbial activity andgrowth,andmayshiftthestoichiometricbalancebetweenC,N,andP.Thereby,exudatesheightenmicrobial nutrient demand and acquisition of N and P from organic matter, leading to an increase in enzyme production. Aim of this study was to determine environmental controls of extracellular enzyme production, and hence on potential enzyme activities (V max ) and substrate afnities (K m ). To determine the controlling factors, we worked onfourspatialscalesfromthemicroscale(i.e.rhizosphere)throughthemesoscale(i.e.soildepth)andlandscape scale (relief positions), and fnally to the continental scale (1200km transect within the Coastal Cordillera of Chile). Kinetics of seven hydrolyzing enzymes of the C, N, and P cycles (cellobiohydrolase, β‑glucosidase, β‑xylosidase, β‑N‑acetylglucosaminidase, leucine‑aminopeptidase, tyrosine‑aminopeptidase, and acid phospha- tase) were related to soil texture, C and N contents, pH, and soil moisture via redundancy analysis (RDA). Potential activities of C, N, and P acquiring enzymes increased up to 7-times on the continental scale with rising humidity of sites and C and N contents, while substrate afnities simultaneously declined. On the landscape scale, neither V max norK m ofanyenzymediferedbetweennorthandsouthslopes.Fromtop-tosubsoil(downto 120cm depth) potential activities decreased (strongest of aminopeptidases under humid temperate conditions with up to 90%). Substrate afnities, however, increased with soil depth only for N and P acquiring enzymes. Afnities of cellobiohydrolase and β‑xylosidase, on the contrary, were 1.5- to 3-times higher in top- than in subsoil. Potential activities of N and P acquiring enzymes and β‑glucosidase increased form bulk to roots. Simultaneously, substrate afnities of N and P acquiring enzymes declined, whereas afnities of β‑glucosidase increased. These trends of activities and afnities in the rhizosphere were signifcant only for acid phosphatase. The RDA displayed a strong relation of potential activities of C and P acquiring enzymes and β‑N‑acetylglucosaminidase to C and N contents in soil as well as to the silt and clay contents. Aminopeptidase activity was mainly dependent on soil moisture and pH. We conclude that substrate availability for micro- organisms mainly determined enzyme activity patterns on the continental scale by the humidity gradient. Patterns on the meso- and microscale are primarily controlled by nutrient limitation, which is induced by a shift of the stoichiometric balance due to input of easily available C by roots in the rhizosphere. 1. Introduction Extracellular enzymes, originating largely from plant roots and soil microorganisms (Burns et al., 2013), catalyze soil organic matter de- composition (SOM). Enzymes split organic polymers into soluble mo- lecules and ions, which can be assimilated by microorganisms and https://doi.org/10.1016/j.geoderma.2018.10.030 Received 21 June 2018; Received in revised form 8 October 2018; Accepted 19 October 2018 ⁎ Corresponding author. E-mail address: svenja.stock@forst.uni-goettingen.de (S.C. Stock). Geoderma 337 (2019) 973–982 0016-7061/ © 2018 Elsevier B.V. All rights reserved. T