Objective Fertility and ecological stoichiometric characteristics of surface soil at the land converted for tea cultivation in Wuyi Mountain were studied.

Methods Surface soil specimens at 0-15cm depth were collected at the plantations with a history of cultivating tea for 0-10, 20-30, and 40-50 years in Wuyi Mountain. For comparison, soil samples were also collected in the weed-covered virgin lands adjacent to the tea plantations. Contents of organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), and total potassium (TK) as well as pH and electrical conductivity (Ec) of the soil samples were determined. C/N, C/P, C/K, N/P, N/P, and reservoir capacity of SOC and TN were calculated.

Results (1) Compared with neighboring virgin land of each sampling site, the plantation SOC were lower by 24.55-30.37% with significantly reduced reservoir, while the TN, TP, and TK were higher in varying degrees. The surface soil at the 0-10-year-old plantations had the least with no change on TN on average; and at the 20-30-year-old plantations, TK rose the most by 199.97%. (2) The Ec of the 20-30-year-old tea plantation soil was 121.72% higher than that of the neighboring control lots, and that of the 40-50-year-old plantation soil, 73.43% higher. The soil pH of the 0-10-year-old plantations was 0.7 below control with a 10.46% reduction, 0.3 at the 20-30-year-old plantations (5.52% reduction), and 0.4 at the 40-50-year-old plantations (7.55% reduction). (3) The ratios of C/N, C/P, C/K, N/K, and P/K of the plantation soils were significantly lowered ranging from 0.76% to 56.38%.

Conclusion  Tea cultivation on the mountain lands significantly raised the surface soil TN, TP, TK, and nitrogen storage. The increase was most significant for the 20-30-year-old plantations. Along with it, there was a loss of carbon storage/pools in the soil which exacerbated acidification and induced decline on the ecological stoichiometry (except for N/P).