Table 8.

BIOG driver and its representation in (data = GPASOIL-v0) and (data = GPASOIL-v1).

Driver name	BIOG (natural soil biogeochemical background)
Description of its effect on the soil P	P inherited from natural soils at the time of conversion to agriculture (Eq. 20). P in natural soils was also used to approach P in agricultural soils at the beginning of the simulation (initial conditions, Eqs. 22, 23) and soil P pools at steady-state used to compute the parameter describing the exchanges between pools (Eq. 17).
Corresponding variables in our approach	P content of natural soils for any soil P pools considered, i.e. $P_{i-sol}^{NA}$, $P_{i-lab}^{NA}$, $P_{o-lab}^{NA}$, $P_{o-sta}^{NA}$, $P_{i-prim}^{NA}$, $P_{i-sec}^{NA}$, $P_{i-occ}^{NA}$, in kgP ha−1 for top 0–0.3 m.
Dataset ref used in (data = GPASOIL-v0)	Natural soils P pools for top 0–0.3 m were approached by estimates of current P in unmanaged soils for top 0–0.5 m provided by Yang et al.4. Pi-sol was not considered in GPASOIL-v0.
Issues related to the use of this dataset in GPASOIL-v0	Soil orders used to compute how total P is held in different fractions in Yang et al.4 is likely a poor predictor of soil P pools. In our approach, we assumed that P concentration provided for top 0–0.5 m was representative to the considered top 0–0.3 m soil layer.
Representation in (data = GPASOIL-v1)	We used the dataset of He et al.14 that provides the current soil P distribution for $P_{i-lab}^{NA}$, $P_{i-sec}^{NA}$, $P_{i-prim}^{NA}$, $P_{x-occ}^{NA}$, $P_{o-sta}^{NA}$, $P_{o-sta}^{NA}$. The values we used are representative to the top 0 - 0.3 m soil layer. $P_{i-sol}^{NA}$ is derived from $P_{c,\infty }$ that was prescribed to 0.1 mgP L−1 (but sensitivity to this value was tested).
Characteristics of the spatially explicit dataset used in (data = GPASOIL-v1)	He et al.14 provided the current soil P pools distribution (in mgP (kg of soil)−1) for different soil horizons at half-degree spatial resolution for natural ecosystems (78, 10.6084/m9.figshare.16988029.v2).