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ABSTRACT
At present, reports of the effect of lanthanum on nitrogen cycling in the soil are very detailed, but information on carbon (C) and phosphorus (P) cycling is less reported. We present an investigation into the effects of lanthanum on the pH, microbial biomass C and P and enzyme activities (such as that of β-glucosidase, peroxidase, polyphenol oxidase, acid phosphomonoesterase, phosphodiesterase and phosphotriesterase) in soil in an indoor culture experiment. The results show that the application of lanthanum decreased the pH and had an inhibitory effect on microbial biomass C and P throughout the experiment. The application of lanthanum significantly inhibited most of enzyme activities at the 14th day of the experiment. However, soil samples treated with 100 mg kg−1 of lanthanum significantly stimulated the activity of polyphenol oxidase at the 14th day, and the range 100–300 mg kg−1 stimulated the activities during the 28th day to the 56th day. From the 42nd to the 56th day, the pH and all enzyme activities gradually increased. We inferred that the lanthanum had different effects on microbial biomass C and P and enzymes. We recommended that the amount of the rare earth element applied in a tea garden should be lower than 100 mg kg−1.
Acknowledgements
We thank Dr Shawn Gray (Northwestern University, USA) for a critical reading of the manuscript and the language editing. This research was supported by the National Key Technology Research Program of the Ministry of Science and Technology of China [2008BAK51B01], the National Natural Science Foundation of China [31372052] and the Science and Technology Plan Projects in Sichuan Province [2011SZ0320, 2011SZZ023, 2013SZ0110].
Disclosure statement
No potential conflict of interest was reported by the authors.