Potential effect of melanised endophytic fungi on levels of organic carbon within an Alfisol

Soil Research ◽  
2017 ◽  
Vol 55 (3) ◽  
pp. 245
Author(s):  
T. T. Mukasa Mugerwa ◽  
P. A. McGee
Keyword(s):  
Organic Carbon ◽  
Endophytic Fungi ◽  
Cell Walls ◽  
Agricultural Soils ◽  
Soil Aggregates ◽  
Sustainable Use ◽  
Potential Effect ◽  
Aromatic Carbon ◽  
Experimental Soil

Levels of organic carbon within agricultural soils in Australia continue to decline predominantly due to intensive cultivation. Such practices place sustainable use of agricultural soils at risk. The aim of the present study was to test whether selected melanised endophytic fungi could enhance organic carbon in an experimental soil. In a compartmental pot study, 20 melanised endophytic fungi significantly increased carbon in an aggregated carbon-rich Alfisol over 14 weeks, with increases of up to 17% measured. Two of these fungi increased organic carbon within microaggregates. This study demonstrates that some melanised endophytic fungi have the potential to increase levels of organic carbon within an experimental soil. Melanin, a polyaromatic compound present within the cell walls of melanised endophytic fungi, may have contributed towards increases in organic carbon, particularly if protected within soil aggregates. Deposition of aromatic carbon within aggregates would leave this carbon less susceptible to oxidation and contribute towards long-term carbon storage in soils.

scholarly journals Effect of Cover Crop on Carbon Distribution in Size and Density Separated Soil Aggregates

Soil Systems ◽  
2020 ◽  
Vol 4 (1) ◽  
pp. 6 ◽  
Author(s):  
Michael V. Schaefer ◽  
Nathaniel A. Bogie ◽  
Daniel Rath ◽  
Alison R. Marklein ◽  
Abdi Garniwan ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Cover Crop ◽  
Agricultural Soils ◽  
Soil Aggregates ◽  
Fe Oxide ◽  
Δ13c Values ◽  
Density Fractions ◽  
Soil Fraction ◽  
Significant Difference ◽  
Split Field

Increasing soil organic carbon (SOC) stocks in agricultural soils can contribute to stabilizing or even lowering atmospheric greenhouse gas (GHG) concentrations. Cover crop rotation has been shown to increase SOC and provide productivity benefits for agriculture. Here we used a split field design to evaluate the short-term effect of cover crop on SOC distribution and chemistry using a combination of bulk, isotopic, and spectroscopic analyses of size-and density-separated soil aggregates. Macroaggregates (>250 µm) incorporated additional plant material with cover crop as evidenced by more negative δ13C values (−25.4‰ with cover crop compared to −25.1‰ without cover crop) and increased phenolic (plant-like) resonance in carbon NEXAFS spectra. Iron EXAFS data showed that the Fe pool was composed of 17–21% Fe oxide with the remainder a mix of primary and secondary minerals. Comparison of oxalate and dithionite extractions suggests that cover crop may also increase Fe oxide crystallinity, especially in the dense (>2.4 g cm−3) soil fraction. Cover crop δ13C values were more negative across density fractions of bulk soil, indicating the presence of less processed organic carbon. Although no significant difference was observed in bulk SOC on a mass per mass basis between cover and no cover crop fields after one season, isotopic and spectroscopic data reveal enhanced carbon movement between aggregates in cover crop soil.

Long‐term influence of phosphorus fertilization on organic carbon and nitrogen in soil aggregates under no‐till corn–wheat–soybean rotations

2020 ◽  
Vol 112 (4) ◽  
pp. 2519-2534 ◽  
Author(s):  
Sangeeta Bansal ◽  
Xinhua Yin ◽  
Hubert J. Savoy ◽  
Sindhu Jagadamma ◽  
Jaehoon Lee ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Soil Aggregates ◽  
Phosphorus Fertilization ◽  
Carbon And Nitrogen ◽  
No Till

scholarly journals Long-Term Biosolids Application on Land: Beneficial Recycling of Nutrients or Eutrophication of Agroecosystems?

Soil Systems ◽  
2022 ◽  
Vol 6 (1) ◽  
pp. 9
Author(s):  
Murray B. McBride
Keyword(s):  
Trace Metals ◽  
Organic Carbon ◽  
Nutrient Loading ◽  
Agricultural Soils ◽  
Soil Health ◽  
Water Soluble ◽  
Amended Soils ◽  
The Impact ◽  
Biosolids Application

The impact of repeated application of alkaline biosolids (sewage sludge) products over more than a decade on soil concentrations of nutrients and trace metals, and potential for uptake of these elements by crops was investigated by analyzing soils from farm fields near Oklahoma City. Total, extractable (by the Modified Morgan test), and water-soluble elements, including macronutrients and trace metals, were measured in biosolids-amended soils and, for comparison, in soils that had received little or no biosolids. Soil testing showed that the biosolids-amended soils had higher pH and contained greater concentrations of organic carbon, N, S, P, and Ca than the control soils. Soil extractable P concentrations in the biosolids-amended soils averaged at least 10 times the recommended upper limit for agricultural soils, with P in the amended soils more labile and soluble than the P in control soils. Several trace elements (most notably Zn, Cu, and Mo) had higher total and extractable concentrations in the amended soils compared to the controls. A radish plant assay revealed greater phytoavailability of Zn, P, Mo, and S (but not Cu) in the amended soils. The excess extractable and soluble P in these biosolids-amended soils has created a long-term source of slow-release P that may contribute to the eutrophication of adjacent surface waters and contamination of groundwater. While the beneficial effects of increased soil organic carbon on measures of “soil health” have been emphasized in past studies of long-term biosolids application, the present study reveals that these benefits may be offset by negative impacts on soils, crops, and the environment from excessive nutrient loading.

scholarly journals Fluvial sedimentary deposits as carbon sinks: organic carbon pools and stabilization mechanisms across a Mediterranean catchment

2019 ◽  
Vol 16 (5) ◽  
pp. 1035-1051 ◽  
Author(s):  
María Martínez-Mena ◽  
María Almagro ◽  
Noelia García-Franco ◽  
Joris de Vente ◽  
Eloisa García ◽  
...  
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Forest Soils ◽  
Agricultural Soils ◽  
Basal Respiration ◽  
Carbon Sinks ◽  
Sediment Sources ◽  
Catchment Scale ◽  
Upland Soils

Abstract. The role of fluvial sedimentary areas as organic carbon sinks remains largely unquantified. Little is known about mechanisms of organic carbon (OC) stabilization in alluvial sediments in semiarid and subhumid catchments where those mechanisms are quite complex because sediments are often redistributed and exposed to a range of environmental conditions in intermittent and perennial fluvial courses within the same catchment. The main goal of this study was to evaluate the contribution of transport and depositional areas as sources or sinks of CO2 at the catchment scale. We used physical and chemical organic matter fractionation techniques and basal respiration rates in samples representative of the three phases of the erosion process within the catchment: (i) detachment, representing the main sediment sources from forests and agricultural upland soils, as well as fluvial lateral banks; (ii) transport, representing suspended load and bedload in the main channel; and (iii) depositional areas along the channel, downstream in alluvial wedges, and in the reservoir at the outlet of the catchment, representative of medium- and long-term residence deposits, respectively. Our results show that most of the sediments transported and deposited downstream come from agricultural upland soils and fluvial lateral bank sources, where the physicochemical protection of OC is much lower than that of the forest soils, which are less sensitive to erosion. The protection of OC in forest soils and alluvial wedges (medium-term depositional areas) was mainly driven by physical protection (OC within aggregates), while chemical protection of OC (OC adhesion to soil mineral particles) was observed in the fluvial lateral banks. However, in the remaining sediment sources, in sediments during transport, and after deposition in the reservoir (long-term deposit), both mechanisms are equally relevant. Mineralization of the most labile OC (the intra-aggregate particulate organic matter (Mpom) was predominant during transport. Aggregate formation and OC accumulation, mainly associated with macroaggregates and occluded microaggregates within macroaggregates, were predominant in the upper layer of depositional areas. However, OC was highly protected and stabilized at the deeper layers, mainly in the long-term deposits (reservoir), being even more protected than the OC from the most eroding sources (agricultural soils and fluvial lateral banks). Altogether our results show that both medium- and long-term depositional areas can play an important role in erosive areas within catchments, compensating for OC losses from the eroded sources and functioning as C sinks.

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