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Stabilization mechanisms of organic ...

Jagadamma, Sindhu.

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Stabilization mechanisms of organic carbon in two soils of the Midwestern United States.

紀錄類型:	書目-語言資料,印刷品 : Monograph/item
正題名/作者:	Stabilization mechanisms of organic carbon in two soils of the Midwestern United States./
作者:	Jagadamma, Sindhu.
面頁冊數:	194 p.
附註:	Source: Dissertation Abstracts International, Volume: 70-06, Section: B, page: 3243.
Contained By:	Dissertation Abstracts International70-06B.
標題:	Agriculture, Soil Science. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3362098
ISBN:	9781109206760

Stabilization mechanisms of organic carbon in two soils of the Midwestern United States.
Jagadamma, Sindhu.

Stabilization mechanisms of organic carbon in two soils of the Midwestern United States. - 194 p.

Source: Dissertation Abstracts International, Volume: 70-06, Section: B, page: 3243.

Thesis (Ph.D.)--The Ohio State University, 2009.

The overall goal of this research project was to evaluate the stable soil organic carbon (SOC) fraction isolated by physical and chemical methods in terms of pool size, structural composition, and turnover rates in two major soils of the Midwestern United States.

ISBN: 9781109206760Subjects--Topical Terms:

1017824
Agriculture, Soil Science.

Stabilization mechanisms of organic carbon in two soils of the Midwestern United States.
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245 1 0 $a Stabilization mechanisms of organic carbon in two soils of the Midwestern United States.
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500 $a Source: Dissertation Abstracts International, Volume: 70-06, Section: B, page: 3243.
500 $a Adviser: Rattan Lal.
502 $a Thesis (Ph.D.)--The Ohio State University, 2009.
520 $a The overall goal of this research project was to evaluate the stable soil organic carbon (SOC) fraction isolated by physical and chemical methods in terms of pool size, structural composition, and turnover rates in two major soils of the Midwestern United States.
520 $a There is general agreement that wet oxidation methods isolate stable SOC fractions more effectively than other chemical methods. To determine the efficiency of the three widely used oxidizing agents (hydrogen peroxide, H 2O2; disodium peroxodisulphate, Na2S2O 8 and sodium hypochlorite, NaOCl) for stable SOC isolation, horizon-wise soil samples from four land uses (woodlot, grassland, no-till and conventional-till continuous corn [Zea mays L.]) at Wooster, OH were evaluated. The results showed that among the land uses and horizons, the proportion of total SOC resistant to oxidation was lower and similar for Na2S 2O8 (4 to 43%) and H2O2 (7 to 46%) as compared to NaOCl (38 to 79%).
520 $a A comparative evaluation of SOC associated with all physical fractions indicated that sand and silt-associated SOC quickly changed with land use conversion from native vegetation to agricultural crops. Although soil texture at both locations was dominated by silt-sized particles, most of the SOC pool was associated with the clay fraction. Interestingly, the clay associated SOC in agricultural soils of Wooster continues to increase, albeit at a slower rate, with increase in total SOC concentration, while it attained maximum saturation capacity in the Mollisol at Monmouth. A more pronounced influence of agricultural management practices on physically isolated SOC fractions was observed at the Wooster site after 45 years of experimentation, than at the Monmouth site after 10 years of experimentation. It was unclear whether the observed difference in the effect of management practices on SOC was due to the difference in experimental duration or soil types.
520 $a Recent literature suggests that combining various fractionation techniques could result in more precise separation of SOC fractions with distinct stability. This approach was tested in the last study by comparing the pool sizes and turnover rates of the stabilized fraction of SOC isolated by physical and chemical methods individually and in combination. The pool sizes were evaluated for soils from both Wooster and Monmouth, while the turnover rates using 13C natural abundance technique was calculated only for the Wooster site, where there is a clear vegetation shift from C3 forest to C4 corn. In general, the pool size of the stable SOC fraction isolated by physical methods (silt and clay-associated SOC) was significantly higher (10.7 to 64.8% of total SOC) than that isolated by chemical methods (1.3 to 25.6% of total SOC) in both surface and subsurface soils. In surface soils, the SOC isolated by combining physical and chemical methods resulted in longer turnover rates than that isolated by the individual methods, while in the subsoil, different methods did not influence substantially the turnover rates of the stable SOC pool.
520 $a A great deal of research conducted so far on SOC dynamics focused primarily on how total SOC pool changes with environmental and management changes. However, because diverse SOC stabilization mechanisms operate at varying degrees, the total SOC pool is highly heterogeneous in terms of structural composition and stability. The biggest challenge is to identify and characterize the different fractions of SOC pool that cycles at different rates. There are several techniques available currently to segregate the total SOC into different compartments, but the relative performance of these techniques is questionable. The findings from this dissertation research provide valuable information on the size and stability of SOC fractions separated by common fractionation methods. (Abstract shortened by UMI.)
590 $a School code: 0168.
650 4 $a Agriculture, Soil Science. $3 1017824
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710 2 $a The Ohio State University. $3 718944
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790 $a 0168
791 $a Ph.D.
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