Soil net nitrogen mineralisation across global grasslands.

Risch, A C; Zimmermann, S; Ochoa-Hueso, R; Schütz, M; Frey, B; Firn, J L; Fay, P A; Hagedorn, F et al. · Nat Commun · 2019

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Abstract

Soil nitrogen mineralisation (N<sub>min</sub>), the conversion of organic into inorganic N, is important for productivity and nutrient cycling. The balance between mineralisation and immobilisation (net N<sub>min</sub>) varies with soil properties and climate. However, because most global-scale assessments of net N<sub>min</sub> are laboratory-based, its regulation under field-conditions and implications for real-world soil functioning remain uncertain. Here, we explore the drivers of realised (field) and potential (laboratory) soil net N<sub>min</sub> across 30 grasslands worldwide. We find that realised N<sub>min</sub> is largely explained by temperature of the wettest quarter, microbial biomass, clay content and bulk density. Potential N<sub>min</sub> only weakly correlates with realised N<sub>min</sub>, but contributes to explain realised net N<sub>min</sub> when combined with soil and climatic variables. We provide novel insights of global realised soil net N<sub>min</sub> and show that potential soil net N<sub>min</sub> data available in the literature could be parameterised with soil and climate data to better predict realised N<sub>min</sub>.