ASSESSMENT OF CARBON DYNAMICS IN INDO-GANGETIC PLAINS OF U. P. USING GEOMATICS

Abstract

Soil Organic Carbon (SOC) is important for the soil fertility and crop production. The assessment of soil organic carbon dynamics can help in monitoring the effect of land use change in the context of global warming and climate change. Global warming phenomenon and climate change has a great role of CO2. Among greenhouse gases CO2 shares major (50%) responsibility of global warming. The CO2 concentration is gradually increasing in atmosphere since 12 century (250 ppmv) onwards up to 378 ppmv in 2005. The average annual emissions of 8.5 Pg Cyr"1 during the 1990s is from the combustion fossil fuels (6.3±0.4 Pg Cyr"1) and changes in land use (2.2±0.8 Pg Cyr"1). The average annual accumulation of carbon is 6.1 Pg C yr"1 of which the accumulation in the atmosphere (3.2±0.2 Pg Cyr"1), the annual uptake by the oceans (2.4±0.7 Pg Cyr"1), and vegetative regrowth in the northern hemisphere (0.5±0.5 Pg C yr"1). The missing C02 | #- sink of 2.4 PgC yr"1 is not in the ocean and may be within soil. The soil organic carbon (SOC) pool is the largest component of terrestrial carbon pools (Wang et. al., 2005), and therefore an increase in sequestration of atmospheric CO2 of the soil-plant system and stabilization of SOC may play a pivotal role in controlling global warming (Mosier, 1998; Su et. al., 2006; Crosson, 1989; White et. al., 2000; Lai, 1999; Hobbie et. al, 2000; Johnsen et. al., 2001). Stabilization of SOC can also help in maintaining the soil physical properties and health. The Indo-Gangetic plain (IGP) covers 13% of the geographical area of India. It produces nearly 50% food grain of the country and feeds 40% population of the country (Abrol and Gupta, 1998). Hence the present study has been undertaken in IGP Uttar Pradesh. Cropping pattern map of study area is generated using four season AWiFs data. The soil sampling locations are determined by integrating cropping pattern, soil map (Singh et al., 2004). Homogeneous composite units are considered for soil sampling. Soil ii samples are collected from 242 locations spread over the study area. The physicochemical properties are analysed using standard methods. The SOC is analysed with CHN analyser and SIC is analysed by acid-base titration method (Jackson, 1973). The soil carbon pool was computed by the method suggested by Batjes (1996). Twelve different cropping patterns are delineated and mapped in Indo-Gangetic plain, Uttar Pradesh using multidate Indian Remote Sensing Satellite (IRS)-P6 Advanced Wide Field Sensor (AWiFS). Four dominant cropping patterns (i.e. rice-wheat, sugarcane-wheat, maize/jowar-wheat and jowar-pulses) among the twelve different cropping patterns are found in the study area. The forests accounts for 6.32% of the total geographical area. The net cropped area is 20282159.46 ha (84.18% of the total geographical area) and the non-agricultural area observed is 3437376.00 ha (14.26% of total geographical area). Rice is the single most dominant crop of the state occupying about 32.94% of the total geographical area during kharif season. Maize/jowar is the second major cereal crop next to the rice accounting for 13.77 %of the total geographical area of the state. The major crops grown during rabi season are wheat, and pulses oilseed covering an area of 7979267.71 ha (33.12%) and 5974742.58 ha (24.80%), respectively. Rice-wheat, sugarcane and rice-pulses are the major cropping pattern occupying about 3958739.85 ha (16.43%), 3609939.74 ha (14.98%), and 2511298.24 ha (10.42%) respectively. The areas under pulses/oilseed are significantly higher in the rabi season. Sugarcane-wheat and pulses are almost shared equal area (6.49%). Maize/jowar-wheat cropping pattern is occupying 6.14% of the total geographical area of the state. Single cropping patterns i.e. rice-fallow, fallow-pulses, fallow-wheat, maize fallow and sugarcane-fallow, are minor cropping pattern which are occupying 6.08%,2.94%, 4.06%, 2.69%, 2.51%, respectively. Waste land including gulley, salt affected, waterlogged and rocky land accounted for 3.80% of the total geographic area of the state. The value of in Multiple Cropping Index (MCI) and Cultivated Land Utilization Index (CLUI) shows that the study area belongs to high cropping intensity. The total carbon content of Uttar Pradesh at 0-15 cm, 0-30 cm, 0-50 cm, 0-100 cm and 0-150 cm depth are 0.70, 1.33, 2.07, 3.73, and 5.26 Pg respectively. The soil organic carbon (SOC) stock increases with depth of the soil. The SOC content of Uttar Pradesh at 0-15 cm, 0-30 cm, 0-50 cm, 0-100 cm and 0-150 cm depth are 0.53, 0.96, 1.42, 2.27 and 2.97 Pg respectively. The SIC content of Uttar Pradesh at 0-15 cm, 0-30 cm, 0-50 cm, 0- 100cm and 0-150 cm depth are 0.17, 0.36, 0.66,1.46, and 2.35 Pg respectively. The physiographic unit eastern plateau exhibits maximum organic carbon density 29.81 x 106 to 34.94 x 106g ha"1, followed by Vindhyan range (30.07 x 106 to 31.70 x 106 g ha"1). Both the units are under dense forest. Minimum soil organic carbon content is exhibited by the side slope of Siwalik hill. Among the other physiographic units old alluvial plain with ox bows shows higher value of Soil Organic Carbon (SOC). The Soil Organic Carbon (SOC) content is also estimated for all the soil subgroups. The maximum soil organic carbon (SOC) is observed for and Typic Paleustalfs and minimum value of SOC was found for Aerie Fluvaquents. Intermediate SOC content is observed for Typic Haplustepts, the largest soil subgroup in the study area. The cropping pattern and land use influence the SOC content. Forested land shows higher SOC content. The order of SOC content under various land use and cropping pattern is in the order of Forest> Rice - Wheat > Sugarcane-Wheat > Maize-Wheat > wastelands > Maize-Pulses/Oilseeds. Active flood plain and recent alluvial plain shows higher SIC values. The minimum SIC content in undulating land with hillocks of eastern Rajasthan upland is followed by the side slopes of Siwalik hill. The SIC content of Udic Haplustepts on tarai shows the lower value in rice-wheat cropping system. The order of maximum SIC content in different soil type are as Aerie Fluvaquents>Typic Ustifluvents>Fluventic Haplustepts. IV The minimum SIC value is noticed for Dystric Eutrochrepts. Udifluventic Haplustepts /Typic Ustipsamment which is formed under recent flood plain show higher SIC. The waste land (mainly saline / sodic soils) shows higher inorganic carbon as compare to crop land. The trend of SIC content of various cropping pattern is in the order of waste land > maize- pulses/oilseed > maize -wheat > sugarcane-wheat > rice -wheat> forest. SIC follows the reverse trend of SOC. Spatial variability and distribution of SOC at 0-30 cm of simple kriging exponential model is shown the superiority over other. A significant autocorrelation and reliable semivariograms are obtained for SOC content. The nugget to-sill ratio defines the spatial dependence property. The semivariogram shows moderate nugget effect, which accounts for about 43% of the total sill if they are fitted with a theoretical model. SOC is ranging from 2.3 to 99.92 (xl06g ha"1) with an average 39.49 (xl06g ha"1). Spatial variability of SOC shows the decreasing trend from the north eastern part to south eastern part of the study area. Exponential model of ordinary kriging for SOC at 0-100 cm depth shows the superiority over other semivariogram models with nugget to sill ratio 0.093. This shows a strong spatial dependence for soil organic carbon. The trend of SOC decreased from north to south. The eastern most part and north western part of the study area show lower SOC density. The lower value in central most part might be attributed to recent alluvium. The lowest value of SOC in north-western most part might be due to severe erosion in the Siwalik hill. Indicator kriging shows superior predictability for SIC content both at 30 cm with nugget to sill ratio 0.7772. It shows poor spatial dependence (Liu et al 2006) because high SIC values are confined to southernmost part of the study area. SIC density increased from northern part to southern part. Salt affected land showed highest values of SIC. Higher value of SIC are attributed to jowar- pulsed. Forest lands shows minimum SIC values followed by rice- wheat. Therefore, SIC is showed the reverse trend of SOC. The CENTURY model is validated with estimated soil organic carbon values from the long term experiment of rice-wheat cropping system (1988-2000) conducted at Indo-Gangetic alluvial plain, Ludhiana. The model is run using the site characteristics which are the basic inputs for the model. The modeling efficiencies for the treatment T4, T5 and T7 were 0.87, 0.93 and 0.97 respectively. It indicates that model performance is satisfactory. In all three treatments modeled output followed the trend of the actual data reasonably well. The correlation coefficients for all the treatments are observed more than 0.9. The century simulated values are higher than that of estimated values. The estimation of soil carbon is performed using di-chromate titration method. This titration method fails to give 100% recovery. The century simulated SOC for 100 years of four dominant cropping patterns to understand the future scenario in Indo-Gangetic plain (IGP) of Uttar Pradesh. Initially there is a slow decreased in SOC pool for three cropping patterns namely rice-wheat, sugarcane-wheat and maize/jowar-wheat. But for jowar-pulses up to 1965 SOC pool is constant. For first three cases there is a conversion of single crop i.e. rice-fallow, rice or maize/jowar-fallow, jowar-fallow to intensive cultivation of double cropping system since green revolution. The model simulated SOC under rice-wheat and sugarcane-wheat system is shown a sharp increased. After 1995 this increase is slowed down and tending to attain towards equilibrium. The rice -wheat cropping pattern shows increasing trend, whereas sugarcane - wheat shows quasi equilibrium. The overall SOC stock up to 2030 for rich-wheat cropping pattern (rotation) shows increasing trend. However, the nearly stable SOCpools under jowar/ maize-wheat might be attributed to constant management VI and cropping practices. Jowar-pulses cropping system showed decreasing trend in SOC pool. vn