Biodegradation of 2,4-D herbicide as affected by Its adsorption-desorption behaviour and microbial activity of soils

Soil Research ◽  
1996 ◽  
Vol 34 (6) ◽  
pp. 1041 ◽  
Author(s):  
NS Bolan ◽  
S Baskaran
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Carbon Content ◽  
Microbial Activity ◽  
Clay Content ◽  
Freundlich Isotherm ◽  
Surface Concentration ◽  
Initial Increase ◽  
Organic Carbon Content ◽  
Adsorption Desorption

The adsorption-desorption behaviour and the degradation of an ionic herbicide (2,4-D) were examined using 10 soils from New Zealand that differed in their organic matter and clay content. Adsorption isotherms for 2,4-D were adequately described by the Freundlich isotherm and the values of the exponent N of the Freundlich isotherm were close to 1 (0.92-0.98), indicating that the adsorption isotherm tended to become linear. The extent of adsorption, as measured by the distribution coefficient (Kd), increased with an increase in soil organic carbon. The rate of desorption of 2,4-D followed first-order reaction kinetics with respect to surface concentration, and decreased with an increase in the organic carbon content of the soils. The rate of degradation of 2,4-D, as measured by the half-life (t1/2), decreased with an initial increase in soil organic carbon, which is attributed to the increase in adsorption. With increasing adsorption, the rate of desorption decreased, resulting in a low concentration of 2,4-D in the soil solution that is available for microbial degradation. When the organic carbon content was more than 12%, however, both the adsorption and rate of degradation increased. The enhanced degradation of 2,4-D at these levels of organic carbon may be related to the increased biological activity of the soil, as measured by substrate-induced respiration, and the decreased 2,4-D-induced inhibitory effect on microbial activity.

Space-time monitoring of soil organic carbon content across a semi-arid region of Australia

2021 ◽  
Vol 24 ◽  
pp. e00367
Author(s):  
Patrick Filippi ◽  
Stephen R. Cattle ◽  
Matthew J. Pringle ◽  
Thomas F.A. Bishop
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Carbon Content ◽  
Arid Region ◽  
Space Time ◽  
Organic Carbon Content ◽  
Soil Organic Carbon Content ◽  
Semi Arid Region ◽  
Semi Arid

scholarly journals Soil age and soil organic carbon content shape biochemical responses to multiple freeze–thaw events in soils along a postmining agricultural chronosequence

2021 ◽  
Author(s):  
Christoph Rosinger ◽  
Michael Bonkowski
Keyword(s):  
Microbial Biomass ◽  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Carbon Content ◽  
Organic Carbon Content ◽  
Freeze Thaw ◽  
Biochemical Responses ◽  
Microbial Responses ◽  
Soil Age ◽  
Carbon Losses

AbstractFreeze–thaw (FT) events exert a great physiological stress on the soil microbial community and thus significantly impact soil biogeochemical processes. Studies often show ambiguous and contradicting results, because a multitude of environmental factors affect biogeochemical responses to FT. Thus, a better understanding of the factors driving and regulating microbial responses to FT events is required. Soil chronosequences allow more focused comparisons among soils with initially similar start conditions. We therefore exposed four soils with contrasting organic carbon contents and opposing soil age (i.e., years after restoration) from a postmining agricultural chronosequence to three consecutive FT events and evaluated soil biochgeoemical responses after thawing. The major microbial biomass carbon losses occurred after the first FT event, while microbial biomass N decreased more steadily with subsequent FT cycles. This led to an immediate and lasting decoupling of microbial biomass carbon:nitrogen stoichiometry. After the first FT event, basal respiration and the metabolic quotient (i.e., respiration per microbial biomass unit) were above pre-freezing values and thereafter decreased with subsequent FT cycles, demonstrating initially high dissimilatory carbon losses and less and less microbial metabolic activity with each iterative FT cycle. As a consequence, dissolved organic carbon and total dissolved nitrogen increased in soil solution after the first FT event, while a substantial part of the liberated nitrogen was likely lost through gaseous emissions. Overall, high-carbon soils were more vulnerable to microbial biomass losses than low-carbon soils. Surprisingly, soil age explained more variation in soil chemical and microbial responses than soil organic carbon content. Further studies are needed to dissect the factors associated with soil age and its influence on soil biochemical responses to FT events.

scholarly journals Regional simulation of soil organic carbon dynamics for dry farmland in Northeast China using the CENTURY model

PLoS ONE ◽  
2021 ◽  
Vol 16 (1) ◽  
pp. e0245040
Author(s):  
Feng Zhang ◽  
Shihang Wang ◽  
Mingsong Zhao ◽  
Falv Qin ◽  
Xiaoyu Liu
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Carbon Content ◽  
Regional Scale ◽  
Organic Carbon Content ◽  
Century Model ◽  
Carbon Sequestration Potential ◽  
Soil Organic Carbon Content ◽  
Sequestration Potential ◽  
Temporal And Spatial

Soil organic carbon content has a significant impact on soil fertility and grain yield, making it an important factor affecting agricultural production and food security. Dry farmland, the main type of cropland in China, has a lower soil organic carbon content than that of paddy soil, and it may have a significant carbon sequestration potential. Therefore, in this study we applied the CENTURY model to explore the temporal and spatial changes of soil organic carbon (SOC) in Jilin Province from 1985 to 2015. Dry farmland soil polygons were extracted from soil and land use layers (at the 1:1,000,000 scale). Spatial overlay analysis was also used to extract 1282 soil polygons from dry farmland. Modelled results for SOC dynamics in the dry farmland, in conjunction with those from the Yushu field-validation site, indicated a good level of performance. From 1985 to 2015, soil organic carbon density (SOCD) of dry farmland decreased from 34.36 Mg C ha−1 to 33.50 Mg C ha−1 in general, having a rate of deterioration of 0.03 Mg C ha−1 per year. Also, SOC loss was 4.89 Tg from dry farmland soils in the province, with a deterioration rate of 0.16 Tg C per year. 35.96% of the dry farmland its SOCD increased but 64.04% of the area released carbon. Moreover, SOC dynamics recorded significant differences between different soil groups. The method of coupling the CENTURY model with a detailed soil database can simulate temporal and spatial variations of SOC at a regional scale, and it can be used as a precise simulation method for dry farmland SOC dynamics.

Sign in / Sign up

Export Citation Format

Share Document