Thumbnail Image

Thesis

Browse

20131
Reset filters
Subject: Soil Science × Author: Boparai, Arpandeep Kaur × Start date: 2012 × Thesis Type: M.Sc ×
Reset filters

Search Results

Now showing 1 - 1 of 1
  • Thumbnail Image
    ThesisItemOpen Access
    TEMPERATURE DEPENDENCE OF CARBON MINERALIZATION FROM ACTIVE, SLOW AND PASSIVE POOLS OF SOIL ORGANIC MATTER
    (Punjab Agricultural University, Ludhiana, 2013) Boparai, Arpandeep Kaur
    The present investigation was conducted to study the effect of temperature on C mineralization from active, slow and passive pools of soil organic matter (SOM) in comparison to bulk soil. Laboratory incubation experiments were conducted at 15, 25, 35 and 450C temperature and field capacity moisture to study C mineralization from three isolated SOM fractions viz. >250 μm, 53-250 μm and <53 μm that respectively represent active, slow and passive pools of SOM. During 54 days of incubation at different temperatures, the highest amount of C (1196-13104 mg C kg-1) was mineralized from >250 μm SOM fraction, followed by 53-250 μm fraction (305-1955 mg C kg-1) and the lowest from <53 μm fraction (258-1263 mg C kg-1). The amount of C mineralized from bulk soil ranged between 249 and 1047 mg C kg-1 at different temperatures. For a given SOM fraction and bulk soil C mineralization rate was highest at 450C and lowest at 150C. The C mineralization rates (mg C kg-1 d-1) at different temperatures ranged between 72 and 375 for >250 μm fraction, 26-149 for 53-250 μm fraction, 9-105 for <53 μm fraction and 7-91 for bulk soil. Of the total organic C, 66 percent of C was mineralized in >250 μm fraction, 60 percent of C in 53-250 μm fraction, 10 percent of C <53 μm fraction and 14 percent from bulk soil. First order single compartment kinetic model provided good fit to all the data sets and yielded high coefficient of determination (R2=0.864 to 0.999). Different SOM fractions differed significantly with respect to temperature sensitivity of decomposition. The Q10 values for decomposition of different SOM fractions ranged between 1.8 - 2.0 for >250 μm fraction, 1.6-1.8 for 53-250 μm fraction and 1.4-1.6 for <53 μm fraction. Bulk soil showed temperature sensitivity similar to <53 μm fraction with Q10 values ranging between 1.4 and 1.5 for different treatments. The higher Q10 values for SOM fraction >250 μm suggested that decomposition of labile fraction was affected to a greater extent by increase in temperature as compared to other stable fractions. Since the labile pool of SOM (>250 μm fraction) constituted only about 4-5 percent of the bulk soil organic matter, the results suggest that the effect of global warming on soil organic C content will probably be small.