Organic acid accumulation under flooded soil conditions in relation to the incorporation of wheat and rice straws with different C:N ratios

Abstract

Crop residues are important agricultural resources and incorporating wheat straw into rice fields is becoming an alternative to open-field burning after wheat harvest in rice-wheat rotation systems. Organic acids are important soil constituents that are believed to be linked to many biological and environmental processes in the soil, including nutrient cycling, phytotoxicity, metal solubility and greenhouse gas formation. A number of studies have focused on the impact of wheat straw incorporation on organic acid accumulation under flooded soil conditions, but information on the relationship between organic acid accumulation and the properties of wheat straw, especially the C:N ratio, and the response of organic acid accumulation to N application is rare. In this study, incubation experiments were conducted to investigate the difference in organic acid (formic, acetic, propionic and butyric acids) accumulation in soil solution under flooded conditions between wheat and rice straw incorporation, and the relationship between the C:N ratio of the straw materials and organic acid accumulation. Results showed that the concentration of organic acids in the soil solution increased with the rate of straw incorporated. The overall accumulation of organic acids was higher when soil was incorporated with wheat straw than with rice straw. The concentration in soil solution decreased more with wheat straw incorporation because of its higher C:N ratio. The addition of urea-N significantly enhanced CH 4 flux and reduced the concentration of organic acids in soil solution in the wheat straw treatment, whereas CH 4 flux and the concentration of organic acids in the rice straw treatment were less sensitive to the addition of urea-N. The practical implication of the results obtained in this study to N management in rice fields is also discussed.

Short-term effect of organic residue incorporation on soil aggregate stability along gradient in salinity in the lower cheliff plain (Algeria)

“…Our results underpin many studies which claim that soil organic amendment led to a decrease in pH (Ok et al, 2011;Bai et al, 2013). Moreover, wheat straw contains more cellulosic compounds than cattle manure and various organic acids can be released by cellulose degradation (Shan et al, 2008).…”

Free-air CO2 enrichment (FACE) enhances the biodiversity of purple phototrophic bacteria in flooded paddy soil

“…The increased organic C input could have less impact on microbial diversity in the rhizospheric soil than in the bulk soil. Besides, tissues of plants grown under elevated atmospheric CO 2 often transmit their own nitrogen depletion to the microbial population in the soil (Gifford et al 2000;Jongen et al 1996;Owensby et al 1993b;Shan et al 2008). Because they are in direct contact with plants, microorganisms in the rhizosphere are more prone to be suppressed by the limited nutrients than microbes inhabiting bulk soils.…”

Returning Winter Cover Crop Residue Influences Soil Aggregation and Humic Substances under Double-cropped Rice Fields

“…Results from Bechtold and Naiman (2009) suggest that basic influences on SOM retention in these paddy soils are not functionally different than those that apply to upland soils. Other research results showed that SOM sequestration improved with the addition of organic matter and straw incorporated into paddy soils (Shan et al, 2008;Kader et al, 2011). Returning winter cover crop residues to the soil as fertilizer affected the soil physical properties.…”