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Carbon mineralization potential and soil carbon pool under different land uses in South Kashmir

KrishiKosh

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Title Carbon mineralization potential and soil carbon pool under different land uses in South Kashmir
 
Creator Monisa Raza
 
Contributor Tahir Ali
 
Subject Soil organic carbon pools, microbial biomass, water soluble organic carbon, labile carbon, non-labile carbon, carbon mineralization and kinetics
Soil Science
 
Description PhD Thesis submitted to SKUAST Kashmir
Carbon (C) is the fundamental building block of all life on earth and is the sixth-most abundant element in the universe. Soil samples were collected from surface (0-15 cm) and sub-surface (15-30 and 30-45 cm) under four land uses namely agriculture, forest, horticulture and grassland. In case of agriculture and grassland samples were collected from two depths viz. 0-15 and 15-30 cm while as in case of horticulture and forest samples were collected from three depths namely 0-15, 15-30 and 30-45 cm. Soil samples were analyzed for various fractions of carbon and it was observed that these forms were in the order; total organic > non labile > oxidisable > very labile > less labile > labile > total inorganic> microbial biomass > water soluble under all land uses. All forms of carbon except very labile and labile carbon were highest in forest land use while these above mentioned forms i.e. very labile and labile carbon were highest in case of grassland. In general a depth-wise decrease in content was observed for most forms (WSOC, MBC, OOC, TOC and labile fractions viz. VLC, LLC and LC) of carbon except for TIC As observed from coefficient of correlation, pH, bulk density, WHC, CEC, sand, silt and CaCO3 were related to various C fractions. CEC was positively correlated with TOC, TC, WSOC, MBC, OOC, VLC and LLC in the surface and subsurface layer. . It was observed that sand fraction had a negative relation whereas silt had a positive relation with different C fractions at various depths. TOC, TC, OOC and VLC had a negative relationship with BD. TIC had a positive relationship with BD and CaCO3 at all soil depths. TOC, TC, OOC, WSOC, MBC, VLC and LC were positively and significantly related with most C fractions. TIC was not significantly correlated with TOC except in the forest land use.
Carbon mineralization was carried out for surface (0-15 cm) and sub-surface (15-30 cm) under all land uses. Cumulative mineralized carbon was highest for grassland land use with a mean value of 1460.36 mg/kg followed by forest land use with a mean value of 1443.19 mg/kg while as the lowest was observed in agricultural land use. It was observed that the CO2-C mineralized decreased with depth i.e. highest values were observed in surface soils (0-15 cm) than in subsurface soils (15-30 cm) under all land uses. Cumulative carbon mineralized was plotted against incubation period and for all four land uses and both depths, a slower rate of organic carbon mineralization in the latter stages of incubation was observed. In all the land uses, maximum mineralization was observed in 5th week and after that the rate of release of mineralized carbon decreased rapidly up to 7th week and then remained almost constant. The value of rate constant (k) for active carbon of double exponential kinetic model was observed highest for grassland for both depths with value of 0.39 and 0.36 week-1 respectively and lowest for agricultural land use for both depths with value of 0.23 and 0.20 week-1 respectively. The rate constant (k) of single exponential kinetic model also followed the same trend as above with highest value observed in forest land use. The values of all kinetic parameters were higher for surface soils than sub-surface soils. Similarly the value of rate constant (h) for slow carbon pool of double exponential kinetic model was highest for forest for both depths. Double exponential kinetic model fitted better than single first order kinetic model which was clear from values of R2 (coefficient of determination) which are higher in case of double exponential model in both the soil depths.
SKUAST Kashmir
 
Date 2016-12-21T13:06:02Z
2016-12-21T13:06:02Z
2015
 
Type Thesis
 
Identifier http://krishikosh.egranth.ac.in/handle/1/91784
 
Language en
 
Format application/pdf