Table 3. Descriptive statistics of soil properties from the 0–20 cm layer in nine cities in Hubei province (n = 405).

Soil properties	Minimum	Maximum	SE	CV (%)	Mean	Recommended rangea
pH	4.9	8.76	0.55	6.96	7.88	4-6
Organic matter, g kg-1	0.94	19.42	2.97	43.55	6.73	>10
N, mg kg-1	1.96	314.01	35.55	112.52	31.56	50-100
P, mg kg-1	1.2	385.85	43.72	111.43	28.33	30-60
K, mg kg-1	33.45	507.42	69.13	55.39	125.31	78-156
Ca, mg kg-1	892	6048	916	34	2694	300-1000
Mg, mg kg-1	26.25	830.1	139.16	57.26	244.35	100-500
S, mg kg-1	1.93	146.31	23.87	74.74	31.92	24-40
Fe, mg kg-1	5.03	149.74	21.21	64.37	32.94	20-30
Cu, mg kg-1	0.43	23.65	2.82	73.34	3.87	3.0-4.0
Mn, mg kg-1	1.71	146.44	20.38	84.82	23.9	6.0-15.0
Zn, mg kg-1	0.91	43.06	5.63	88.49	6.38	3.0-6.0
B, mg kg-1	0.01	5.33	0.88	101.8	0.86	0.6-1.00

^aAccording to Portch and Hunter [7] and Whitcomb [9].