Season and Nitrogen Effects on Activities of Three Hydrolytic Enzymes in Soils of the Gurbantunggut Desert, Northwest China

Abstract

The activities of three extracellular hydrolytic enzymes, soil invertase, urease, and alkaline phosphatase (AlP), were measured across seasons and with the experimental addition of nitrogen (N) in the soil of the Gurbantunggut Desert, Northwest China. Seasonal fluctuations in hydrolytic enzyme activities were not correlated with seasonal variations in soil temperature, water content, pH, conductance, and organic carbon. Invertase and AlP activities increased with low rates of N addition, peaked at a N addition rate of 3.0 g N m⁻² y⁻¹, and then decreased at higher N addition rates. Urease activity decreased with increasing N addition. Higher organic matter content in the upper depths of soil resulted in higher hydrolytic enzyme activity at depths of 0–5 cm in soil samples and hydrolytic enzyme activity at that depth was more sensitive to N addition and seasonal environmental factors than that at depths of 5–10 cm in soil samples.

Keywords:

• Alkaline phosphatase
• conductance
• invertase
• nitrogen deposition
• organic matter
• pH
• urease

Acknowledgments

We are grateful to students such as Liu Xing, Wu Shuo, Chen Xi, Lu Ling and many others from Xinjiang Agricultural University for their many hours of soil nutrient and enzyme activity analyses.

Additional information

Funding

The study was jointly supported by the National Natural Science Foundation of China (41001181) and the International Science and Technology Cooperation Program of China (2010DFA92720).