Comparative carbon stability in surface soils and subsoils under submerged rice and upland non-rice crop ecologies: A physical fractionation study

Deb, Shovik; Kumar, Deo; Chakraborty, Somsubhra; Weindorf, David C.; Choudhury, Ashok; Banik, Pabitra; Deb, D. L.; De, Parijat; Saha, Sushanta; Patra, Alok Kumar; Majhi, Munmun; Naskar, Puspendu; Panda, Parimal; Hoque, Anarul

doi:10.1016/j.catena.2018.12.037

Cited by 7 publications

(5 citation statements)

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“…Physical fractionation of soils was done to comprehend soil structure and C distribution within aggregates and in attachment with mineral matrix [ 35 , 36 , 38 , 54 ]. In density fractionation, heavy density fraction represented humified/ amorphous organic matter attached to soil mineral matrix [ 55 ] whereas light density fraction represented loose and undecomposed plant/ organic residues [ 55 , 56 ].…”

Section: Discussionmentioning

confidence: 99%

“…While humic substances and soil particles combine to form microaggregates, microbial polysaccharides, organic mucilages bind the microaggregates into larger macroaggregates [ 61 ]. Conversely, tillage operations break-down the macroaggregates in croplands, exposing physically protected C to soil microorganisms and causing C loss from soils [ 36 , 62 ]. In this study, highest and lowest soil macroagegate formation was observed in forest and cropland soils.…”

Section: Discussionmentioning

confidence: 99%

“…The change in LULC also affected soil macro and microaggregate occluded C. Highest aggregate occluded C was found in forest soils followed by soils of converted and croplands. In soils, aggregates protect the encrusted C from microbial decomposition [ 36 , 63 ]. Therefore, higher soil aggregation leads to a longer turnover time of C or pathway of its sequestration [ 61 ].…”

Section: Discussionmentioning

confidence: 99%

“…For density fractionation, sodium polytungstate (SPT) was used as the heavy liquid [ 35 ]. After adjusting the density to 1.6 g cm -3 , the samples were shaken in repeated cycles and filtered by Whatman glass filter paper (0.7 μ m pore size) to separate light and heavy density fractions [ 36 ]. The fractions were further analyzed in Vario EL III elemental analyzer (Elementar, Germany) to measure C associated with heavy and light fractions.…”

Section: Methodsmentioning

confidence: 99%

“…The sieves were mechanically shaken vertically for 2 mins with 10 mm amplitude. The weight of the soil samples, collected in each of the sieves, were measured and then used to calculate aggregate stability indices like mean weight diameter (MWD) and geometric mean diameter (GMD) as per the following equations [ 36 , 38 ].…”

Section: Methodsmentioning

confidence: 99%

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Soil quality under different land uses in eastern India: Evaluation by using soil indicators and quality index

Deb

et al. 2022

PLoS ONE

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Indian soils are inherently poor in quality due to the warm climate and erosion. Conversion of land uses like forests to croplands and faulty management practices in croplands further cause soil degradation. This study aimed to understand the extent of these impacts in a small representative part of eastern India, covering Himalayan terai and nearing alluvial plains. Soils were collected from (i) forests, (ii) croplands (under agricultural practices for more than 50–60 years) and (iii) converted lands (converted from forests to croplands or tea gardens over the past 15–20 years). Different soil quality indicators were assessed and soil quality index (SQI) was generated to integrate, scale and allot a single value per soil. Results indicated that continuous organic matter deposition and no disturbances consequence the highest presence of soil carbon pools, greater aggregation and maximum microbial dynamics in forest soils whereas high application of straight fertilizers caused the highest available nitrogen and phosphorus in cropland soils. The SQI scorebook indicated the best soil quality under forests (x¯ 0.532), followed by soils of converted land (x¯ 0.432) and cropland (x¯ 0.301). Comparison of the SQI spatial distribution with land use and land cover confirmed the outcome. Possibly practices like excessive tillage, high cropping intensity, no legume in crop rotations, cultivation of heavy feeder crops caused degraded soil quality in croplands. This study presented an example of soil quality degradation in India due to land use change and faulty management practices. Such soil degradation on a larger scale may affect future food security.

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