Effect of No-Till Farming and Straw Mulch on Spatial Variability of Soil Respiration in Sloping Cropland

Abstract

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 CO 2 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 ). 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.

Short Term Effects of Preceding Crops and Tillage Methods on Soil CO₂ Fluxes in the Cropland of the North China Plain

“…%), respectively; a, b, A and B are constant coefficients. The temperature sensitivity values of SR (Q 10 ) based on Equation (3) [9] was calculated as:…”

“…Total amount of soil respiration (TSR) in experimental period was calculated by interpolating the average CO 2 flux between two sampling dates, and computing the sum of the products of the average flux and the time between respective sampling dates for each measurement period [9,19] as follows:…”

“…Agricultural practices contribute about 25% of total anthropogenic carbon dioxide emission, meanwhile, the various agricultural practices also deeply change soil physicochemical characteristics and then influence SR and C storage in cropland soils [8]. Release of CO 2 from cropland soils to atmosphere due to agriculture practices plays an important role in the global C cycle [9].…”

“…Conservation practices, including no-tillage (NT) and crop rotation, play important role in controlling soil erosion, enhancing crop productivity and improving soil fertility and microbial activities [8][9][10][11]. Tillage methods can directly change soil bulk density, soil water content, carbon availability, and all of them can affect the microbial activities that in turn, affect the soil respiration [11][12][13].…”