Thumbnail Image

Thesis

Browse

20101
Reset filters
Author: Debasish Saha × End date: 2010 ×
Reset filters

Search Results

Now showing 1 - 1 of 1
  • Thumbnail Image
    ThesisItemOpen Access
    EFFECT OF LAND USE ON SOIL AGGREGATION AND SOIL ORGANIC CARBON FOOTPRINT IN SHIWALIKS OF PUNJAB
    (Punjab Agricultural University, 2010) Debasish Saha
    An understanding of the effect on land use on soil structural stability and soil organic carbon (SOC) is of paramount importance for framing strategies for soil quality management in the present context of increasing atmospheric CO2 concentration. A study was thus conducted in lower Shiwaliks of Punjab (i) to study the impact of different land uses on soil aggregation in relation to soil erodibility and (ii) to study the SOC fractions in different sized aggregates and SOC sequestration under different land uses. Two different approaches of determining aggregate stability were used i.e. by shaking under water and that determined with single simulated rain drop technique (SISRT). The SOC fractions viz. hot water soluble carbon (HWC), particulate organic carbon (POC), labile carbon (LC) were determined. The 1-m profile C stock was determined under different land uses. The concentration of SOC was highest in 0-15 cm layer of grassland soils and lowest in eroded soils but in 15-30 cm layer, it was highest in forest soils. The mean weight diameter (MWD) was highest for surface soils of grasslands (1.13 mm) and lowest in eroded lands (0.19 mm). The SISRT followed the similar trend as MWD. In surface soils, the water-stable macro-aggregates (WSA>2mm) were highest in grassland soils (17.3%) whereas, the micro-aggregates (WSA<0.25mm) were highest (25%) in eroded soils. The SOC in WSA>2mm varied from 7.93 g kg-1 in eroded soils to 17.3 g kg-1 in grassland soils, whereas the SOC in WSA<0.25mm was similar. The SOC decreased with increase in aggregate size and was highest in 1-2 mm aggregates for all the land uses. Among the SOC fractions, the POC was most dominant but LC and HWC showed vulnerability to land use change. The POC was highly correlated (r = 0.83) with wet aggregate stability (WSA>0.25mm) whereas, HWC had good correlation (r = 0.88) with SISRT. The total SOC stock in 1-m profile was highest in forest (83.5 Mg ha-1) and lowest in eroded (55.6 Mg ha-1) soils. The grassland soils had highest C stock (42.5% of total SOC stock) in 0-15 cm soil layer, whereas forest soils stored 73% of the total SOC stock in the subsurface (15-100 cm) layers. The aggregate bulk density was higher than that of whole soils. The water holding capacity of grasslands was highest whereas saturated hydraulic conductivity was similar in forest and grassland soils.