Table 1. The soil characteristics of 65 grassland sampling sites.

Soil type	AI	AB	pH	SOC	TN	TP	AN	AP	TC:N	TC:P	TN:P	AN:P
Anthrosol	0.20	194 ± 22b	8.0 ± 0.1a	0.1 ± 0.02c	0.01 ± 0.00d	0.2 ± 0.01b	5.2 ± 0.3ab	3.8 ± 0.3ab	10.0 ± 2.0a	7 ± 2c	0.7 ± 0.04c	1.4 ± 0.1abc
Arenosol	0.31	201 ± 39b	7.6 ± 0.1ab	1.3 ± 0.3abc	0.11 ± 0.02abcd	0.3 ± 0.03b	7.6 ± 0.6ab	4.0 ± 0.4ab	21.2 ± 2.8a	35 ± 5bc	2.9 ± 0.5bc	3.1 ± 0.5abc
Calcisol	0.25	169 ± 36c	7.9 ± 0.1a	0.7 ± 0.1c	0.06 ± 0.01cd	0.3 ± 0.02b	6.1 ± 0.3ab	4.1 ± 0.3ab	21.1 ± 6.7a	27 ± 4bc	2.2 ± 0.3bc	1.9 ± 0.3abc
Cambisol	0.42	149 ± 35c	6.4 ± 0.1c	2.5 ± 0.3ab	0.26 ± 0.02ab	0.4 ± 0.02b	12.4 ± 2.0a	1.6 ± 0.2b	9.7 ± 0.6a	66 ± 6ab	6.9 ± 0.4ab	7.9 ± 0.9a
Chernozem	0.48	269 ± 11bc	6.5 ± 0.1bc	2.5 ± 0.3ab	0.23 ± 0.03abc	0.3 ± 0.01b	11.6 ± 1.1ab	2.8 ± 0.9ab	10.7 ± 0.1a	95 ± 11a	8.9 ± 1.1a	5.6 ± 2.2ab
Gleysol	0.17	20 ± 3d	8.5 ± 0.1a	0.4 ± 0.03c	0.02 ± 0.00d	0.2 ± 0.04b	6.0 ± 0.4ab	3.4 ± 0.6ab	17.4 ± 0.8a	18 ± 3c	1.0 ± 0.2c	1.9 ± 0.2abc
Greyzem	0.42	325 ± 19bc	7.6 ± 0.02ab	1.4 ± 0.1abc	0.11 ± 0.01abcd	0.7 ± 0.13a	2.5 ± 0.1b	2.8 ± 0.3ab	12.9 ± 0.3a	21 ± 7bc	1.6 ± 0.5c	0.9 ± 0.1bc
Kastanozem	0.33	253 ± 27c	7.5 ± 0.1abc	1.2 ± 0.1abc	0.11 ± 0.01abcd	0.3 ± 0.01b	8.7 ± 0.6ab	3.5 ± 0.2ab	12.3 ± 0.3a	44 ± 2bc	3.8 ± 0.2bc	4.4 ± 0.6abc
Leptosol	0.37	280 ± 21bc	7.7 ± 0.1a	1.2 ± 0.03abc	0.10 ± 0.00bcd	0.4 ± 0.01b	3.0 ± 0.4b	5.1 ± 0.2ab	12.3 ± 0.5a	33 ± 1bc	2.7 ± 0.1bc	0.6 ± 0.1c
Phaeozem	0.48	296 ± 61bc	6.6 ± 0.1bc	2.9 ± 0.2a	0.28 ± 0.02a	0.5 ± 0.05ab	9.2 ± 0.6ab	4.3 ± 0.4ab	10.2 ± 0.3a	67 ± 4ab	6.7 ± 0.5ab	3.1 ± 0.5abc
Solonchack	0.44	462 ± 33a	6.6 ± 0.02bc	2.0 ± 0.1abc	0.18 ± 0.01abcd	0.5 ± 0.01ab	12.9 ± 0.7a	5.8 ± 1.2a	11.2 ± 0.3a	45 ± 1bc	4.0 ± 0.1bc	2.4 ± 0.4abc
mean	0.35	241 ± 19	7.4 ± 0.1	1.5 ± 0.1	0.14 ± 0.01	0.4 ± 0.01	8.2 ± 0.3	3.8 ± 0.1	14.5 ± 1.0a	44 ± 2.0	4.0 ± 0.2	3.5 ± 0.3

Data are means ± 1 SE. The soils are classified according to the Harmonised World Soil Database (HWSD, version 1.21) released by FAO. Different letters indicate significant (P < 0.05) differences among soil types. Abbreviations: AI, aridity index (unitless); AB, aboveground biomass (g m⁻²); SOC, soil organic carbon (%); TN, soil total nitrogen (%); TP, soil total phosphorus (%); AN, available nitrogen (ppm); AP, available phosphorus (ppm); TC:N, ratio of total carbon to nitrogen; TC:P, ratio of total carbon to phosphorus; TN:P, ratio of total nitrogen to phosphorus; AN:P, ratio of available nitrogen to phosphorus.