Soil enzymes catalyze key biochemical processes in organic matter decomposition and nutrients cycles and are regarded as indicators of soil quality. In this study, we investigated the impact of 4 consecutive years of biochar (corncob; 360°C) amendment on dynamics of enzyme activities (i.e., invertase, urease, catalase, and alkaline phosphatase) during the winter wheat (Triticum aestivum L.) growing period in Northern China. The experiment consisted of four treatments: control (CK), biochar rate at 4.5 t · ha−1 · y−1 (B4.5), biochar rate at 9.0 t · ha−1· y−1 (B9.0), and crop straw return (SR). Four times throughout the wheat growth period (i.e., 5 Nov. 2010; 26 Mar. 2011; 25 Apr. 2011; 5 Jun. 2011), we determined the enzyme activities down to the 30-cm depth of the soil profile (i.e., 0–5, 5–10, 10–20, and 20–30 cm). Results showed that there were considerable fluctuations in enzyme activities across the observed period and depths. All enzyme activities decreased significantly in deeper soil horizons. High biochar amendment rates (B9.0) lead to the peak activities of invertase, urease, and phosphatase occurring in the 0- to 5-cm layer on 25 Apr. 2011 samples. The greatest catalase activity under B9.0 was found on 26 Mar. 2011 samples. In addition, the effect by B4.5 and SR on enzyme activities was variable and limited. These data support the conclusion that consecutive application of biochar for 4 years increased enzyme activities, which potentially influence soil nutrients dynamics under field condition, although the effects were dependent on sampling depth and time.
Key Laboratory of Agricultural Environment, Ministry of Agriculture; and Agricultural Clear Watershed Group, Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, Beijing, China.
Address for correspondence: Qingzhong Zhang, No. 12 Zhongguancun South St, Haidian District, Beijing, 100081, People’s Republic of China; E-mail: email@example.com
This work was supported by the National Scientific Foundation of China (40701090 and 41201288) and the S&T Innovation Program of Chinese Academy of Agricultural Sciences. The authors report no conflicts of interest.
Received October 11, 2013.
Accepted for publication April 16, 2014.