Temporal changes in carbon sequestered in soils of different agricultural land uses in sub montaneous Punjab
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Date
2020
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Punjab Agricultural University, Ludhiana
Abstract
The present investigation was conducted to study distribution of organic carbon pools under
different land uses in sub montaneous Punjab and to study temporal changes in carbon
sequestration after eight years. Two sites viz. Takarla and Mukerian and four land uses viz.
cropland, forest, agroforestry and grassland were selected for the study. Soil pH varied from
slightly alkaline to moderate alkaline at Takarla, whereas at Mukerian, soil pH was slightly
alkaline. At both sites, EC was higher in cropland. Forest soils had higher silt and clay content at
Takarla, while grassland had higher silt content at Mukerian. Bulk density at both sites was higher
in cropland. CEC was highest in cropland (at Takarla) and forest (at Mukerian). At both sites,
highest available N was found in forest as well as agroforestry system and lowest in cropland.
Cropland had highest available P and K at both sites. At Takarla, Zn was highest in agroforestry
and Cu as well as Fe were highest in grassland. At Mukerian, there was no significant difference
among different land uses at surface layer for both Cu and Fe. At both sites, Mn content was nonsignificantly
different among different land uses. Water-stable macro-aggregates (WSA>2mm)
were higher in grassland as well as agroforestry and microaggregates were higher in agroforestry
and cropland at both sites. Microaggregates had lower C as compared to macro-aggregates at both
sites in all land use systems. Soil organic carbon (SOC) was more in forest (0.64%) at Takarla and
in grassland (1.45%) at Mukerian. At Takarla, HWC (520 mg kg-1), LC (1627 mg kg-1), IC (8.07
mg kg-1) and mineralizable C were more in agroforestry whereas, mineralizable N was more in
forest. At Mukerian, HWC (1450 mg kg-1), LC (2026 mg kg-1), IC (3.29 mg kg-1) and
mineralizable C were more in grassland whereas, mineralizable N was more in agroforestry. At
both sites, total POC was more in forest. From 2010 to 2018 at Takarla, SOC stock (Mg ha-1)
increased from 7.52 to 8.02 in cropland, 8.78 to 12.48 in forest, 8.90 to 9.59 in agroforestry and
7.02 to 10.35 in grassland. At Mukerian, SOC stock (Mg ha-1) decreased from 28.67 to 25.60 in
cropland, 29.7 to 28.33 in forest, 37.21 to 33.93 in grassland and increased from 19.85 to 24.53 in
agroforestry, from 2010 to 2018. Carbon sequestration seems to be more in agroforestry at Takarla
and in grassland at Mukerian. At Mukerian, values for carbon fractions were high as compared to
Takarla, due to comparatively low temperature which decreased the rate of decomposition of soil
organic matter.
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Citation
Sharma, Sharma (2020). Temporal changes in carbon sequestered in soils of different agricultural land uses in sub montaneous Punjab (Unpublished M.Sc. thesis). Punjab Agricultural University, Ludhiana, Punjab, India.