Application of Selenocysteine Increased Soil Nitrogen Content, Enzyme Activity, and Microbial Quantity in Camellia oleifera Abel. Forests

Abstract

The effect mechanism of inorganic selenium on soil fertility has been effectively explained, but the effect of selenocysteine as organic selenium on the soil of Camellia oleifera Abel. forests has not been reported. In this study, the soil of a C. oleifera forests under natural conditions was taken as the control, and four treatments, namely selenocysteine (SeCys), cysteine + sodium selenite (Cys + Se), urea + sodium selenite (Ur + Se), and cysteine (Cys), were set up through a pot experiment to analyze the effects of different treatments on the physicochemical properties and biological characteristics of soil in C. oleifera forests. The results showed that SeCys significantly increased the soil total nitrogen content, nitrate nitrogen, and ammonium nitrogen contents compared with the treatment with inorganic selenium. In addition, the application of SeCys improved the activities of soil urease, soil acid phosphatase, soil nitrate reductase, and soil nitrite reductase on day 24 of culture, while under Cys + Se treatment, the activities of these four enzymes showed significant effects on day 32. The effect of SeCys on increasing the number of soil bacteria and fungi was significantly higher than that of other treatments and increased by 800% and 217%, respectively, compared with the control. SeCys also had significant effects on selenium and nitrogen content of Camellia oleifera seedlings. Correlation analysis showed that soil microbial biomass carbon and nitrogen were significantly correlated with soil enzyme activity, suggesting that SeCys could promote enzyme activity in C. oleifera forests by increasing the microbial number and improving microbial metabolism. The results indicated that SeCys could be used as an ingredient in new high-efficiency fertilizers.