Soil Organic Carbon Enrichment Triggers In Situ Nitrogen Interception by Phototrophic Biofilms at the Soil–Water Interface: From Regional Scale to Microscale

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.

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On the rebound: soil organic carbon stocks can bounce back to near forest levels when agroforests replace agriculture in southern India

SOIL Discussions ◽

10.5194/soild-2-871-2015 ◽

2015 ◽

Vol 2 (2) ◽

pp. 871-902 ◽

Cited By ~ 3

Author(s):

H. C. Hombegowda ◽

O. van Straaten ◽

M. Köhler ◽

D. Hölscher

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Tree Species ◽

Regional Scale ◽

Clay Fraction ◽

Carbon Stocks ◽

Southern India ◽

Reference Plot ◽

Soc Stock ◽

Soc Stocks

Abstract. Tropical agroforestry has an enormous potential to sequester carbon while simultaneously producing agricultural yields and tree products. The amount of soil organic carbon (SOC) sequestered is however influenced by the type of the agroforestry system established, the soil and climatic conditions and management. In this regional scale study, we utilized a chronosequence approach to investigate how SOC stocks changed when the original forests are converted to agriculture, and then subsequently to four different agroforestry systems (AFSs): homegarden, coffee, coconut and mango. In total we established 224 plots in 56 plot clusters across four climate zones in southern India. Each plot cluster consisted of four plots: a natural forest reference plot, an agriculture reference and two of the same AFS types of two ages (30–60 years and > 60 years). The conversion of forest to agriculture resulted in a large loss the original SOC stock (50–61 %) in the top meter of soil depending on the climate zone. The establishment of homegarden and coffee AFSs on agriculture land caused SOC stocks to rebound to near forest levels, while in mango and coconut AFSs the SOC stock increased only slightly above the agriculture stock. The most important variable regulating SOC stocks and its changes was tree basal area, possibly indicative of organic matter inputs. Furthermore, climatic variables such as temperature and precipitation, and soil variables such as clay fraction and soil pH were likewise all important regulators of SOC and SOC stock changes. Lastly, we found a strong correlation between tree species diversity in homegarden and coffee AFSs and SOC stocks, highlighting possibilities to increase carbon stocks by proper tree species assemblies.

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Soil Water Characteristics of Gleysols in the Bamenda (Cameroon) Wetlands and Implications for Agricultural Management Strategies

Applied and Environmental Soil Science ◽

10.1155/2021/6643208 ◽

2021 ◽

Vol 2021 ◽

pp. 1-15

Author(s):

Alice Mufur Magha ◽

Primus Azinwi Tamfuh ◽

Lionelle Estelle Mamdem ◽

Marie Christy Shey Yefon ◽

Bertrand Kenzong ◽

...

Keyword(s):

Soil Moisture ◽

Organic Carbon ◽

Soil Organic Carbon ◽

Soil Water ◽

Total Variance ◽

Organic Carbon Content ◽

Available Water ◽

High Soil ◽

Local Soil ◽

Very High

Water budgeting in agriculture requires local soil moisture information as crops depend mainly on moisture available at root level. The present paper aims to evaluate the soil moisture characteristics of Gleysols in the Bamenda (Cameroon) wetlands and to evaluate the link between soil moisture content and selected soil characteristics affecting crop production. The work was conducted in the field and laboratory, and data were analyzed by simple descriptive statistics. The main results showed that the soils had a silty clayey to clayey texture, high bulk density, high soil organic carbon content, and high soil organic carbon stocks. The big difference between moisture contents at wilting point and at field capacity testified to very high plant-available water content. Also, the soils displayed very high contents of readily available water and water storage contents. The soil moisture characteristics give sigmoid curves and enabled noting that the Gleysols attain their full water saturation at a range of 57.68 to 91.70% of dry soil. Clay and SOC contents show a significant positive correlation with most of the soil moisture characteristics, indicating that these soil properties are important for soil water retention. Particle density, coarse fragments, and sand contents correlated negatively with the soil moisture characteristics, suggesting that they decrease soil water-holding capacity. The principal component analysis (PCA) enabled reducing 17 variables described to only three principal components (PCs) explaining 73.73% of the total variance; the first PC alone expressed 45.12% of the total variance, associating clay, SOC, and six soil moisture characteristics, thus portraying a deep correlation between these eight variables. Construction of contoured ditches, deep tillage, and raised ridges management techniques during the rainy season while channeling water from nearby water bodies into the farmland, opportunity cropping, and usage of water cans and other irrigation strategies are used during the dry season to combat water constraints.

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Mercury Dynamics at the Flooded Soil-Water Interface in Reservoirs of Northern Québec: in Situ Observations

Mercury in the Biogeochemical Cycle ◽

10.1007/978-3-642-60160-6_9 ◽

1999 ◽

pp. 165-189 ◽

Cited By ~ 5

Author(s):

Marc Lucotte ◽

Shelagh Montgomery ◽

Maxime Bégin

Keyword(s):

Soil Water ◽

Water Interface ◽

Flooded Soil ◽

In Situ Observations

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Volatile and intermediate volatility organic compounds in suburban Paris: variability, origin and importance for SOA formation

Atmospheric Chemistry and Physics ◽

10.5194/acp-14-10439-2014 ◽

2014 ◽

Vol 14 (19) ◽

pp. 10439-10464 ◽

Cited By ~ 47

Author(s):

W. Ait-Helal ◽

A. Borbon ◽

S. Sauvage ◽

J. A. de Gouw ◽

A. Colomb ◽

...

Keyword(s):

Organic Carbon ◽

Particulate Organic Carbon ◽

Organic Compounds ◽

Regional Scale ◽

Integrated Approach ◽

Anthropogenic Sources ◽

Time Resolved ◽

Times Series

Abstract. Measurements of gaseous and particulate organic carbon were performed during the MEGAPOLI experiments, in July 2009 and January–February 2010, at the SIRTA observatory in suburban Paris. Measurements comprise primary and secondary volatile organic compounds (VOCs), of both anthropogenic and biogenic origins, including C12–C16 n-alkanes of intermediate volatility (IVOCs), suspected to be efficient precursors of secondary organic aerosol (SOA). The time series of gaseous carbon are generally consistent with times series of particulate organic carbon at regional scale, and are clearly affected by meteorology and air mass origin. Concentration levels of anthropogenic VOCs in urban and suburban Paris were surprisingly low (2–963 ppt) compared to other megacities worldwide and to rural continental sites. Urban enhancement ratios of anthropogenic VOC pairs agree well between the urban and suburban Paris sites, showing the regional extent of anthropogenic sources of similar composition. Contrary to other primary anthropogenic VOCs (aromatics and alkanes), IVOCs showed lower concentrations in winter (< 5 ppt) compared to summer (13–27 ppt), which cannot be explained by the gas-particle partitioning theory. Higher concentrations of most oxygenated VOCs in winter (18–5984 ppt) suggest their dominant primary anthropogenic origin. The respective role of primary anthropogenic gaseous compounds in regional SOA formation was investigated by estimating the SOA mass concentration expected from the anthropogenic VOCs and IVOCs (I / VOCs) measured at SIRTA. From an integrated approach based on emission ratios and SOA yields, 38 % of the SOA measured at SIRTA is explained by the measured concentrations of I / VOCs, with a 2% contribution by C12–C16 n-alkane IVOCs. From the results of an alternative time-resolved approach, the average IVOC contribution to SOA formation is estimated to be 7%, which is half of the average contribution of the traditional aromatic compounds (15%). Both approaches, which are based on in situ observations of particular I / VOCs, emphasize the importance of the intermediate volatility compounds in the SOA formation, and support previous results from chamber experiments and modeling studies. They also support the need to make systematic the IVOCs' speciated measurement during field campaigns.

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