Diurnal variations of soil respiration in Bothriochloa ischaemum and Lespedeza davurica mixture pasture at Loess Hilly Region

Soil respiration is an important index for evaluation of soil quality and fertility properties. The clarification of the variations and influence factors of soil respiration in grass-legume mixture pasture will provide evidence for accurately assessment of the effects and response of mixture pasture. In order to comprehensively evaluate the performance of mixture pasture of Bothriochloa ischaemum and Lespedeza davurica, diurnal changes of total soil respiration rate with different mixture ratio of the two species, the contribution of each species and temperature responses of each species were investigated and analyzed in June, 2011 and 2012. The diurnal variation of total soil respiration rates were asymmetric unimodal curves which peaked between 12:00 and 14:00. The daily average of total soil respiration rate decreased in the following order: B. ischaemum monocultureB. ischaemum and L. davurica intercroppingL. davurica monoculture. There were significant correlations between total soil respiration rate and air temperature (P0.05), while there was no significant correlations between soil respiration rate and soil temperature at 5, 10 or 15 cm soil layers. In monoculture, soil respiration rate of B. ischaemum was more sensitive to temperature than that of L. davurica. Q10 values ranged from 1.48 to 2.61 with the highest Q10 value of B. ischaemum monoculture. There was no significant differences between L. davurica monoculture and mixtures.