Geostatistical Assessment of Spatial Variability of Soil Organic Carbon Under Different Land Uses of Northwestern India
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FULL-LENGTH RESEARCH ARTICLE
Geostatistical Assessment of Spatial Variability of Soil Organic Carbon Under Different Land Uses of Northwestern India Bhabani Prasad Mondal1
•
Bharpoor Singh Sekhon2 • R. K. Setia3 • Rahul Sadhukhan4
Received: 17 May 2019 / Accepted: 7 September 2020 Ó NAAS (National Academy of Agricultural Sciences) 2020
Abstract Changes in land use over time can induce spatial variability and these spatial variability patterns may be land use specific. Blanket nutrient management strategies that disregard spatial variability, not only cause economic losses but can impair soil and environmental quality and crop productivity. Geostatistical tools help better in capturing spatial variability than classical tools. This present study was conducted in three different land uses viz., berseem-based, rice–wheat, and poplar-wheat cropping systems prevalent in the northwestern part of India. A total of 144 geo-referenced surface soil samples were collected from these land uses and analyzed chemically to determine SOC and other physicochemical parameters. The highest amount of SOC was associated with poplar-based system, signifying thereby considerable potential for carbon sequestration. The experimental semivariograms models were computed to find the best fitted model for characterizing the spatial pattern of SOC. Gaussian model was found as the best fit for describing the spatial structure of SOC under berseem-based land use; on the other hand, spherical and exponential models were found suitable for rice– wheat and poplar-wheat systems, respectively. The nugget:sill ratio (NS ratio) of SOC was 0.21 for poplar-wheat based land use, suggesting strong spatial dependence, whereas the other land uses exhibited moderate spatial dependence (Berseem based=0.65; Rice-wheat=0.35). Spatial variability maps of SOC were generated using ordinary kriging (OK) technique which helped identify management zones within a field. Keywords Geostatistics Kriging Semivariogram Soil organic carbon Spatial variability
Introduction Owing to variable synergistic action of soil formation processes, soils are supposed to be spatially heterogeneous. These processes operate at different scales [7]. However, & Bhabani Prasad Mondal [email protected] 1
Division of Agricultural Physics, Indian Agricultural Research Institute, New Delhi 110012, India
2
Directorate of Research, Punjab Agricultural University, Ludhiana, Punjab 141004, India
3
Punjab Remote Sensing Centre, Ludhiana, Punjab 141004, India
4
Division of Agronomy, Indian Agricultural Research Institute, New Delhi 110012, India
land use changes over time can induce spatial variability. Besides, spatial variability patterns may be specific to a land use due to the same set of agronomic practices being used for a particular land use. Conventional farming practices use heavy doses of chemical inputs to achieve higher yield in intensive agricultural system. But indiscriminate use of agro-inputs like chemical fertilizers to soil for supplying plant nutrients without
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