e-ISSN: 2582-5208 International Research Journal of Modernization in Engineering Technology and Science Volume:02/Issue:10/October -2020
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SOIL CARBON POOL IN DIFFERENT LAND USES FOR CLIMATE CHANGE MITIGATION AND ADAPTATION IN KOTTAYAM DISTRICT, INDIA Dr Litty Joseph1*and Navya Shaji2 *1Assistant
Professor, Dept. of Chemistry, Kuriakose Elias College, Kerala, India.
2Post-graduate
student, Dept. of Chemistry, Kuriakose Elias College, Kerala, India.
ABSTRACT Climate change has become one of the recently emerged environmental issues, which resulting in a serious threat to the entire environment and human life around the world. It is for the reason, we have to undertake a comprehensive exercise to address the issues of climate change adaptation and mitigation. Studies indicate that 22 per cent of this biomass(~2.4 Pg C/yr) was taken up by the ocean, and 28 per cent (~3.0 Pg C / yr) was absorbed by the terrestrial biosphere, while 6 per cent of the total emissions remain unaccounted for in the sink. Thus, only ~50 per cent of the carbon emitted remained in the atmosphere to induce climate warming during the last decade. Carbon sequestration potential of different land uses plays an important role in regulating the climate of those regions. This paper reviews the influence of land-use changes on soil carbon stocks. For this preliminary study, 5 representative samples were collected from different land use and one from undisturbed native land areas in Kottayam district Kerala. The samples collected were undergone physio-chemical analysis which shows marked spatial variation in carbon content and mineral. Total nitrogen (N) was determined by the Kjeldahl method and soil organic carbon (SOC) content was measured using the modified Walkley–Black wet oxidation procedure. Comparisons of mean differences among land use revealed that soils under native forest contained 4.73% SOC and 0.474% total N, which were significantly greater. Forests play a key role in the carbon cycle as they store huge quantities of organic carbon, most of which is stored in soils, with a smaller part being held in vegetation. So, effective practice in land use will help to pool more carbon in soil mainly in forest soils. Keywords: Climate change, Carbon pool, land coverage
I.
INTRODUCTION
Soil organic carbon is an important element of the global carbon stock and contains approximately two times more carbon than the atmosphere or vegetation [1]. Soil organic carbon and total nitrogen are the key indicators for estimating soil quality and act as important carbon and nitrogen reservoirs [2], and understanding the distribution of SOC and total N stocks are essential in achieving improvements in soil quality[3].Soil organic carbon were influenced by climate, hydrology, soil, land use, abiotic factors and the other biotic factors, while land uses were the most sensitive to display human disturbance. Thus, monitoring the SOC in different land uses is essential for estimating the SOC distribution and stock. The equilibrium of carbon and nitrogen stocks is the result of the inputs and outputs [4,5] of the carbon and nitrogen cycle. Organic carbon losses due to land-use change from grasslands and forests to croplands are estimated 20% to 25% in the zone of cultivation within the first 40-50yrs[6].These decline suggest a fast decrease for the first 20 years, during which soil organic carbon levels gradually stabilise for the next 30 years at anew steady state[7-9]. During the past two centuries, land uses practices have modified decomposition dynamics by changing soil aeration, water dynamics and storage, as well as the biochemistry and quantity of crop residues [10,11]. Land use change has been recognized as a global problem as it is one of the key causes for environmental change. Land uses can be described as the collection of anthropogenic activities ans arrangements in a piece of land for economic and social welfare. Land use practices, controlled by different societal behaviors, contribute to changes in land use that have a detrimental impact on the global environment and biosphere by greenhouse gas pollution and biodiversity modification. The land use transition from forest to agricultural land (deforestation) is one of the anthropogenic sources of elevated atmospheric carbon dioxide levels. Land use and vegetation type have a tremendous impact on soil disturbance. The utilization and maintenance of land with the least soil disturbance helps improve the accumulation of soil OC, while intense disturbance leads to lower soil OC and consequent soil degradation.[12]. Land use changes to the cultivated environment, from a natural www.irjmets.com
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ecosystem (grassland / forest), leads to depletion of soil C up to 50% [12–15]. Cultivated systems can reduce Carbon content by decreasing annual Carbon input and increasing surface disruptions due to mineralization [16]. However, the extent of the land use effect on soil C is not always equal in all soils. The composition of soil minerals, microbs, indigenous organic matter (OM) quantities, etc. can vary. Among all properties, native soil OM content is a significant factor in soil OC accumulation. Under natural conditions, native soil OM levels reflect the equilibrium of Carbon inputs and C losses. By increasing C input and / or decreasing C harvest by adopting enhanced land use and crop management, soils can sequester additional C. With proper land use management system amount of Carbon in long-term grassland, pastoral land and even agricultural land will exceed their native carbon content[17].
II.
METHODOLOGY
Sample collection and analysis In total 5 representative surface soil samples from different agricultural lands-Rubber plantations, Coco Plantations, Mixed plantation(pepper, turmeric, coconut and Banana), Tapioca & Paddy spread over Kottayam district were collected at a depth of 15-30 cm during May 2020 (post-monsoon). One Sample from barren waste land was set as control.
Fig: 1 Topographical map showing sampling sites The soil samples collected were air-dried in shade, gently crushed to powder in a ceramic mortar using pestle and sieved through a 2mm sieve to remove stones, roots, and large organic residues, passed through a 20 mesh sieve to obtain very fine particles which is then stored in clean polyethylene containers before conducting analyses for chemical and physical characteristics, with the samples being numbered from 1 to 6 in accordance with the standard techniques of soil survey (Jackson and Black, 1965, 1968, 1982), the following physical and c hemical analyses were carried out in the soil sample to obtain qualitative and quantitative information. pH pH was determined in the supernatant solution of 1:5 soil/water ratio (w/v) using a pH meter Exchangeable base cations Ca2+, Mg2+, and K+ in soil were extracted by leaching the soil with 1N ammonium acetate at pH 7.0 (w/v), kept for overnight and filtered and was made up to 100ml. The filtrate was used to estimate calcium (Ca 2+) and magnesium (Mg2+) by complexometric titration using standardised EDTA (Jackson, 1973). The potassium (K+ ) in the filtrate was determined using flame photometer. Analysis of soil organic carbon and Total nitrogen (N) SOC content were determined following the wet digestion method of Walkley and Black (20]. Total nitrogen (N) was determined by the Kjeldahl method.
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Estimation of Available Phosphorus Available Phosphorus in the soil samples was determined by leaching the soil with 0.002N H 2SO4 (1 soil : 200 H2SO4 suspension, w/v).Amount of phosphorus in the extract was estimated by chlorostannous reduced phosphomolybdate blue colour method using spectrophotometer at wavelength of 690 nm [19]. Estimating soil organic matter stock from soil organic carbon About 58% of the mass of organic matter exists as carbon. We can estimate the percentage of SOM from the SOC% using the conversion factor 1.72 (derived from 100/58). Organic matter (%) = total organic carbon (%) x 1.72 This conversion factor can vary in different soils, but 1.72 provides a reasonable estimate of SOM for most purposes. Statistical Analysis Correlation analysis was conducted using SPSS and results were plotted with Origin Pro software.
III.
RESULTS AND DISCUSSIONS
The main objective of the study was to quantify the dynamics of soil under various land use practices in the Kot tayam district , where there is no information about the influence of land use on SOC and TN pools.. Six land use: Coco plantation (CP), Native land (NL), Rubber plantation(RP),Paddy field(PF),Tapioca cultivation(TC) and Mixed plantation(MP).The obtained results were shown in the table below. Comparing the five land uses, significantly higher soil organic carbon stock was encountered in the natural forest. In paddy field, organic carbon stock was significantly higher compared with other croplands. However, there was no significant difference in SOC stock of coco plantation and mixed plantation. Table 1. Physio-chemical characteristics of selected soil samples Available Sample ID Organic carbon Phosphorus (%)
Available Potassium
Available Calcium
Available Magnesium
pH
ppm
Total Nitrogen
Organic Matter
(%)
(%)
CP/1/20
1.4
85.9
535
877
66.4
5.6
0.0644
0.2408
RP/2/20
1.6
49.8
55
44.2
13
4.6
0.0736
0.2752
TP/3/20
1.9
131
104
709.4
138.8
5.65
0.0874
0.3268
PF/4/20
2.2
131
85
230.2
77.2
4.15
0.1012
0.3784
MP/5/20
1.4
85.9
105
974.4
53
6.25
0.0644
0.2408
NL/6/20
3.3
135.7
185
2613
141.5
7.55
0.1518
0.5676
The results indicated that soils under the native forest ecosystems have a significantly higher organic carbon and total N than in soils under croplands, which may be a result of higher organic matter accumulation due to increased above and below ground biomass. Conversely, compared to native sites, the organic carbon and total N content of the mineral soil is considerably lower in the croplands, which is likely to be the result of the significantly reduced quantity of organic material returned to the soil system and high levels of soil organic matter oxidation due to land tillage, and loss of organic matter by erosion Cultivation promotes SOC loss due to exposing micro-aggregate organic carbon to microbial decomposition by changing the moisture and temperature regimes.
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Variation in pH
8
pH
6 4 2 0 CP
RP
TP
PF Sample Id
MP
NL
Fig.2: Plots showing variation in pH with respect to different land uses
Variation in SOC &TN 0.16 y = 0.0475x - 0.0056 R² = 0.993
0.14 Total N %
0.12 0.1 0.08 0.06 0.04 0.02 0 0
0.5
1
1.5
soc %
2
2.5
3
3.5
Fig.3: Plots showing correlations of soil organic carbon (SOC) and soil total nitrogen (TN) in samples Correlation between various soil Quality parameters There was a strong significant positive correlation between SOC and TN. Avl. K had low negative correlation with Avl. P, Avl. Ca, and TN. The correlation between studied paramaters are presented in Table 3. From the obtained results we can conclude that Avl. K has a low or non-significant correlation with pH, TN and other exchangeable bases. Table 2. Pearson Correlation Coefficient values among the soil parameters Parameters SOC
SOC 1
TN Avl.Ca Avl. K
TN
Avl. Ca
Avl. K
Avl. Mg
pH
0.99651521 0.73573081 5 1 -0.189401065 0.693002317 0.687922491 0.515840704 1
0.74743217 2 -0.199120955 0.672879731 0.651169362 0.527768525 1
0.219278311 0.482676939 0.661393585 0.943236612 1
-0.088127144 0.037453494 0.202221404
Avl. P
1
Avl.Mg pH www.irjmets.com
Avl. P
0.89607695
0.316381723
1
0.578756916 1
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The overall results indicates that the effect of land uses and soil organic matter has influenced soil Organic Carbon. In order to reveal the capacity of the soil in C storing rather than bulk soil total OC, separated OC pools are the best indicator of OC status.. Cultivation induces OC depletion, which does not inherently mean stable OC depletion. In order to enhance OC storage, less disturbed native soil is best rather, it could depend on the type of vegetation cover, management methods, and type of soil. To investigate the specific explanation for this, further research needs to be done. Although the findings showed a higher proportion of stable OC in soils with a higher native OM content than soils with a lower OM content, also in the latter soils with proper maintenance, the OC storage capacity can be enhanced by daily residue addition, minimal tillage and balance fertilization, even if land is intensively cultivated.
IV.
CONCLUSION
The capacity of soil for sequestering carbon has now become significant in modern agricultural systems, apart from climate change mitigation and adaptation. There is growing international interest in better soil management to increase soil organic carbon (SOC) to contribute to climate change mitigation, to increase climate change adaptation and to sustain food security, through initiatives such as international ‘4p1000’ initiative and the FAO's Global assessment of SOC sequestration potential (GSOCseq) programme. The identification of any system for efficient land-based carbon sequestration requires a quantitative estimate on a regional setting. This work provided a background and scientific significance for the research project on carbon pooling and its impact on global warming. We have correlated and document how nitrogen (N) and phosphorus (P) stoichiometry mediate ecosystem pools Carbon. Considering this as a pilot study we would extend our research to identify both horizontal and vertical agricultural technologies that restore carbon pools and soil quality and create tools to measure, monitor and verify soil-carbon pools and fluxes of greenhouse gas emissions. Soil organic carbon and total nitrogen are the key indicators for estimating soil quality and act as important carbon and nitrogen reservoirs. So understanding the distribution of SOC and total N stocks are essential in achieving improvements in soil quality. The adoption of diverse management strategies of carbon sequestration in croplands, may provide potential estimation of carbon sequestration potential.
ACKNOWLEDGEMENTS We gratefully acknowledge the Kerala State Council Science Technology and Environment (KSCSTE) for providing financial assistance for this research work. We are thankful to the Rubber Research Institute of India (RRII) for extending laboratory facilities.
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[2]
[3] [4] [5] [6] [7]
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