Effect Of No-Till Farming And Straw Mulch On Spatial Variability Of Soil Respiration In Sloping Cropland

The two major techniques of conservation agriculture - no-till and straw mulch - are widely used in agricultural activities. Many studies have investigated the response of soil respiration to conservation agriculture. However, there are few studies estimating soil CO2 emissions in sloping cropland. For this research we selected typical sloping cropland in China's semiarid Loess Plateau region. The spatial heterogeneity of soil respiration under different tillage and straw mulch was investigated using an LI-8100A soil carbon flux measuring system from October 2013 to September 2014. Soil respiration showed a strong seasonal pattern under all treatments, with the highest values in July (3.42-8.26 mu mol m(-2) s(-1)) and the lowest in January (0.16-0.33 mu mol m(-2) s(-1)). No-till increased soil respiration by increasing soil temperature and soil moisture, while straw mulch decreased soil moisture and had the tendency to increase annual total carbon emissions, and straw incorporation had the highest annual total soil carbon emissions (992 g C m(-2)). The slope stage had a visible effect on soil respiration, and soil respiration rates increased in the following order: lower > middle > upper positions under different treatments. The relationship between soil respiration and soil moisture was linear under all treatments; the exponential model was more suitable for simulating the relationship between soil respiration and soil temperature. Temperature sensitivity (Q(10)) values under different treatments ranged from 1.94 to 2.63, and the difference among tillage and straw mulch treatments as a whole was not significant. However, the Q(10) values had a tendency to decrease from summit to foot in tillage treatments, and no-tillage would reduce spatial variability of Q(10) values.