Changes of CO2 emission and labile organic carbon as influenced by rice straw and different water regimes

Abstract

Crop residues under different water regimes can cause significant alterations in soil organic carbon fractions, and in turn, soil-atmospheric carbon dioxide (CO 2 ) emissions. To evaluate the effect of rice straw application on CO 2 emissions and labile organic carbon fractions under different water regimes, an incubation experiment was conducted for 90 days. Ten treatments were developed from the interaction between five water levels (100, 85, 70, 55, and 40 % of water-holding capacity (WHC)) with and without incorporation of rice straw. Peaks of CO 2 fluxes were observed after 13 days of rice straw incorporation, which decreased gradually till the end of the incubation period. The incorporation of rice straw caused significant increases in CO 2 fluxes by 2.77-2.83 times from the paddy soil. In the presence of rice straw, the highest CO 2 fluxes were generally observed at W3 (70 % of WHC), whereas the lowest fluxes were occurred at W1 (100 % of WHC). Addition of rice straw under a range of water regimes markedly improved the transformation of soil organic carbon and labile organic carbon pools such as dissolved organic carbon, microbial biomass carbon, light fraction organic carbon, particulate organic carbon, and permanganate oxidizable carbon. The significant correlations between all labile soil organic carbon fractions and CO 2 concentrations confirmed their important roles in the emission of CO 2 from the paddy soil. In summary, the results suggest that light fraction organic carbon, particulate organic carbon, and permanganate oxidizable carbon were more sensitive indicators for CO 2 emissions and organic matter alterations as compared to other carbon fractions.

Microbiological Indicators of a Clayey Soil Planted with Wheat (Triticum aestivum L.) as Affected by Potassium Fertilization and Different Water Regimes

“…The lowest values of enzyme activities, microbial biomass and microbial counts that noticed at W1 might be resulted from low releasing, transferring and diffusion of soil nutrients. Our results are in agreement with Ibrahim et al (2015), who showed in an incubation experiment to evaluate the effect of different water levels on MBC that addition 70% of WHC caused higher MBC values as compared with 40 and 55% of WHC. Addition of K had a vital role in simulating soil microorganisms and this explained the larger improvements in soil biological properties.…”

Effects of Irrigation Regime and Nitrogen Fertilizer Management on CH4, N2O and CO2 Emissions from Saline–Alkaline Paddy Fields in Northeast China

“…The highest emissions were detected in tillering and late-heading stages, and the highest cumulative emissions of CO 2 were detected in tillering, booting and maturity periods. CO 2 in paddy fields mainly comes from plant and soil respiration [8]. In the green period, plant respiration is weak due to the limitation of biological factors, such as plant height and leaf area.…”

“…SOC also could be the reason why there were more greenhouse gas emissions in longtime tillage paddies [8]. The 57-year-old paddy had a long tillage history, planted rice for many years and accumulated more organic matter [18].…”

“…In the global warming potential for the one hundred year horizon in terrestrial ecosystems, the contribution of CH 4 and N 2 O is 25 and 298 times larger than CO 2 respectively [6]. CH 4 and N 2 O fluxes from paddies contribute approximately 30% and 11% of rural emissions, and paddies also can be either a source or sink of CO 2 [7][8][9]. Soil microbial activities have an effect on the production and uptake of GHG [10] and are impacted by soil characters (e.g., soil temperature, water content and content of NH 4 + and NO 3 − ) [11][12][13][14][15].…”

Ecological restoration of an acidic Cd contaminated soil using bamboo biochar application

“…In the case of biochar, total organic matter content was determined according to the combustion method in a muffle furnace at 540 • C for 6 h (Nelson and Sommers, 1996), and calculated through finding the difference of biochar mass before and after the combustion process. Total nitrogen (N) and phosphorus (P) were measured by the FIA-star 5000 analyzer (Mohamed et al, 2010;Ibrahim et al, 2015), while total cadmium (Cd) contents of soil and biochar were determined by the flame atomic absorption spectrometry (Varian AA240FS) after H 2 SO 4 /HClO 4 (2:1 ratio v/v) digestion. Soil available N and P were measured by Kjeldahl and molybdenum blue methods after their extraction by KCl (2 mol l −1 ) and NaHCO 3 (0.5 mol l −1 , pH 8.5), respectively (Olsen and Sommers, 1982;Jackson, 1973).…”