Changes in temperature sensitivity of soil respiration in the phases of a three-year crop rotation system

Understanding the temperature sensitivity of soil respiration (Q(10)) and its controlling factors plays an important role in accurately estimating soil respiration and carbon cycling in agro-ecosystems. This manuscript presents a case study on how the Q(10) value for soil respiration changes with soil temperature and moisture in the rotation phases. In a three-year crop rotation system (wheat/wheat/millet/pea) in a semi-arid region of China, the soil respiration rate, temperature and moisture were measured under different crop phases from July 2010 to June 2013. The soil respiration rate was significantly lower in the winter wheat phase (1.63 mu mol m(-2) s(-1)) than the millet phase (2.40 mu mol m(-2) s(-1)) and pea phase (2.21 mu mol m(-2) s(-1)). However, the Q(10) value was significantly higher in the wheat phase (2.76) than in the millet phase (1.85) and pea phase (1.47). The relationship between the Q(10) values and soil temperature followed an exponential decay function in the rotation system, and the Q-K, value was stable (1.8) with no obvious variation when the temperature exceeded 15 degrees C. The Q(10) value tended to increase with soil moisture until reaching a threshold of 14.7% soil moisture and then declined. Our results indicate that temperature-respiration empirical models should be parameterized according to crop type in the rotation phases, especially when estimating soil respiration in cold-resistant crops under global warming. (C) 2015 Elsevier B.V. All rights reserved.