Table 2 Global fluxes from soils/arable systems to waters as discussed in recent literature. For comparability, all values were normalized to 1 billion ha of arable land (with original values given in brackets).

Meybeck et al.⁷⁸

All terrestrial land

14 (20)

Based on global particulate P river export to coastal seas calculated from global ratios of particulate carbon to phosphorus

Smil¹⁶

World’s croplands in the mid-1990s

9–10.5

(13–15)

Global erosion rates from Smil⁷⁹, no further details

Mackenzie et al.⁸⁰

All terrestrial land

15.4 (22)

Terrestrial Ocean Atmosphere Ecosystem Model

Liu³⁴

The world’s croplands (1.5 billion ha)

12.8 (19.3)

Extrapolating erosion rates from Pimentel³¹ to global levels

Bouwman et al.¹

Cropland area (1.54 billion ha)

0.7–1.3 (1–2)

Global NEWS Model based on FAO statistics

Cordell et al.³

Arable soils

5.6 (8)

No information on methods or exact area given but P flux due to erosion illustrated in figure

Quinton et al.¹⁵

Agricultural land

10.2–18.5

(14.6–26.4)

Organic:

(2.1–3.9)

Inorganic:

(12.5–22.5)

Based on erosion rates by Van Oost et al.⁷¹ considering water and tillage erosion; no information given, how organic versus inorganic was specified

Chen and Graedel²⁸

Agricultural land 1.1 billion ha

8.2–12

(9–13.2)

Erosion rates based on Liu³⁴

This study

1.04 billion ha of arable land

6.3 (6.3)

Organic:

1.5

Inorganic: 4.6

Erosion rates based on Borrelli et al.³², organic (sum of labile and stable organic) and inorganic P (as sum of labile and inorganic P bound to secondary minerals plus occluded and apatite P) species according to Hedley fractionation³³