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Due to soil organic carbon, agricultural soil has the ability to absorb carbon from the atmosphere. Adopted management techniques and cropping systems have an impact on sequestering carbon. Here, we looked into the fundamental physiochemical characteristics of the soil, the components of SOC, and the microbiological characteristics in five cropping systems namely Maize- black gram, Maize- rice, Maize-soybean, Maize-mustard, Maize- buckwheat and Maize- Vegetable pea. The SOC pool was significantly (P < 0.001) enlarged by the cropping system. Changes in the SOC pool and stability were seen in soil microbial communities, and the main causes were the persistence of saprotrophic fungal dominance and the change in bacterial life-history strategy from K- to R-strategy. SOC fractions were increased via modifications to the agricultural system and microbial community dynamics. Active carbon pools (Mg ha− 1) in soils in 0–15 cm layers of different cropping system was significantly higher in Maize-soybean (10.27) followed by Maize- Vegetable pea (10.12), Maize- black gram (9.53), Maize- buckwheat (9.30), Maize- rice (8.99) and lowest in Maize –mustard (8.57). The carbon pool index was also higher in Maize-soybean (1.18) followed by Maize- Vegetable pea (1.14), Maize- black gram (1.13), Maize- buckwheat (1.11), Maize- rice (1.08) and lowest in Maize –mustard (1.04). Finally, the carbon management index was higher in Maize-soybean (193.54) followed by Maize- Vegetable pea (184.92), Maize- black gram (178.02), Maize- buckwheat (172.77), Maize- rice (165.99), Maize –mustard (136.48). Among the different cropping system, Maize-soybean had greater amount of total soil organic carbon, carbon pool index, lability index and higher carbon management index and hence, considered the best cropping system to sequester carbon in the Sikkim Himalaya. The second and third position was achieved by Maize- Vegetable pea and Maize- black gram with respect to carbon management index. Thus, the study recommended that in the Indian Himalayan study region, maize-soybean farming be encouraged for effective land resource management planning. [ABSTRACT FROM AUTHOR]

Soil organic carbon (SOC) is the main component of carbon in terrestrial ecosystems and an indicator of soil quality. The study aimed to investigate the stock and vertical distribution of SOC fractions and the SOC sequestration of different agroforestry systems (AFS) and other land uses in the Colombian Amazon. In each land use (Secondary forest—SF, Natural regeneration—NR, Alley cropping 1—AC1, Alley cropping 2—AC2, Forest plantations 1—FP1, Forest plantations 2—FP2, Crops in forest plantation—CFP, Shade trees for crops—STC, Homegarden—HG, Silvopastoral system—SPS and Pasture—P), four soil pits were made (1 × 1 × 1 m) to collect soil samples to determine SOC concentration by carbon lability fractions (CVL: very labile, CL: labile, CLL: less labile, CNL: non-labile) and bulk density at four depths (0—10, 10–20, 20–40 and 40–100 cm). The mean SOC concentration was 15.3 ± 1.2 g kg−1, with a higher concentration in 0–10 cm (26.1 ± 2.4 g kg−1). The concentration of the different fractions presented the following order CVL > CNL > CL > CLL (7.4 ± 0.3, 4.8 ± 0.2, 2.7 ± 0.1 and 2.1 ± 0.1 g kg−1, respectively). SOC stock was 13.3 to 220.0 Mg C ha−1 in the 0–100 cm layers, where FP1, FP2, AC1 and AC2 showed the highest values (174.0 to 199.0 Mg ha−1). In contrast, HG, P and STC showed the lowest values with 134.0, 116.0 and 96.2 Mg ha−1, respectively. Therefore, and due to the contribution of the most stable carbon fractions in the soil (CLL and CNL), land uses such as AC1 and AC2 presented the highest levels of carbon stability measured by the carbon management index. Therefore, the different land uses with agroforestry systems increased the amount and stability of carbon accumulated in the soil compared to pasture. [ABSTRACT FROM AUTHOR]

The potential of soil organic carbon fractions for agroforestry systems (AFSs) is not well understood. Five distinct AFSs were tested for its impact on soil organic carbon fractionation, carbon index, and microbial activity in North Eastern Himalayas, India. The mean labile carbon (LC) ranged from 4.55 to 5.43 kg soil−1 across the land use systems. Napier system observed the lowest very labile carbon (VLC) 12.36 kg soil−1 in 60–75-cm depth. The mean non labile carbon (NLC) ranged from 15.67 to 16.83 g kg soil−1 across the land use. Highest less labile carbon (LLC) was observed in agri-horti-silviculture (AHS) followed by agri-silvi-horticulture (ASH) land use system. The black gram + mandarin + Alnus nepalensis land use recorded higher lability index (1.66) followed by maize + Schima wallichii (1.65) in 0–15-cm depth. Among the different land use systems, carbon pool index increased in all the depths over buckwheat + mandarin. The mean carbon management index (CMI) value ranged from 167.02 to 210.12 among the land use system. The mean CMI was highest in black gram + mandarin + Alnus nepalensis (210.12) followed by soybean + Ficus hookerii + guava (191.56), maize + Schima wallichii (281.71), and lowest in buckwheat + mandarin (167.02). Among the AFSs, black gram + mandarin + Alnus nepalensis showed greater amount of carbon pool index, lability index, and carbon management index and, hence, considered the best sustainable agroforestry system to sequester more carbon in the Sikkim Himalaya. Such system also retained more different organic carbon fractions. The mean CMI value ranged from 167.02 to 210.12 among AFSs. Acid phosphatase activity was more during the rainy season followed by winter and summer season. Similar trends were followed by the urease activity in all the three seasons. Overall conclusion from this investigation is that SOC fractions, carbon index, and microbial activity levels are strongly influenced by the prevailing agroforestry systems. [ABSTRACT FROM AUTHOR]

Depending on the type of agricultural use and applied crop rotation, soil organic carbon accumulation may depend, which can lead to less CO2 fixation in the global carbon cycle. Less is known about organic carbon emissions in different crop production systems (cereals, grasses) using different agrotechnologies. There is a lack of more detailed studies on the influence of carbon content in the soil on plant productivity, as well as the links between the physical properties of the soil and the absorption, viability, and emission of greenhouse gases (GHG) from mineral fertilizers. The aim of this study is to estimate the long-term effect of soil organic carbon sequestration potential in different crop rotations. The greatest potential for organic carbon sequestration is Norfolk-type crop rotation, where crops that reduce soil fertility are replaced by crops that increase soil fertility every year. Soil carbon sequestration potential was significantly higher (46.72%) compared with continuous black fallow and significantly higher from 27.70 to 14.19% compared with field with row crops and cereal crop rotations, respectively, intensive crop rotation saturated with intermediate crops. In terms of carbon sequestration, it is most effective to keep perennial grasses for one year while the soil is still full of undecomposed cereal straw from the previous crop. Black fallow without manure fertilization, compared to crop rotation, reduces the amount of organic carbon in the soil up to two times, the carbon management index by 2–5 times, and poses the greatest risk to the potential of carbon sequestration in agriculture. [ABSTRACT FROM AUTHOR]

Soils derived from loess are fertile but susceptible to accelerated degradation in response to agricultural practices. The objective of our study was to evaluate the long‐term effects of alfalfa (Medicago sativa L.) integrated with contrasting organic amendments (29 years) to rejuvenate degraded loess via total soil organic carbon (SOC) sequestration. The replicated study was conducted in concrete lysimeter plots (2 m long × 1 m wide × 60 cm deep) filled with degraded loess materials followed by planting of alfalfa with cattle manure (60 Mg/ha) or vermicompost (27 Mg/ha) amendments. After 29 years, SOC concentration increased by 5.3–6.2‐fold under alfalfa–organic amendments compared to the control. A similar impact of alfalfa–organic amendments was observed on the humic acid, fulvic acid, and humin concentrations. There was an overestimation of SOC stocks (151 ± 48 kg/ha) when equivalent depth was used compared to equivalent mass of soil. While the SOC sequestration rates were 614 ± 129, 710 ± 69, and 744 ± 161 kg/ha/year at 0–10 cm depth under alfalfa, alfalfa–manure, and alfalfa–vermicompost treatments, respectively, the SOC sequestration rates decreased with depth. Significantly higher values of carbon pool index (CPI) and carbon management index (CMI) under alfalfa–organic amendments justified our results associated with the SOC sequestration; however, the SOC lability (CL) decreased under alfalfa–organic amendments, when compared to the control. A significant nonlinear inverse relationship (R2 = 0.80) between the CPI and CL suggested that SOC sequestration is significantly dependent on its lability or vice versa. Our results suggested that the impact of alfalfa–organic amendments significantly rejuvenated the degraded loess soils via SOC sequestration. [ABSTRACT FROM AUTHOR]

There has been limited research on the effect of eucalyptus harvest residue management on soil organic carbon (SOC) in subtropical environments. This research evaluated the effect on soil C indices of the following eucalyptus harvest residue managements: AR, with all forest remnants left on the soil; NB, where bark was removed; NBr, in which branches were removed; NR, which removed all residues; and NRs, which is same as NR but also used a shade net to prevent the litter from the new plantation from reaching the soil surface. C stocks within the soil depths of 0–20 cm and 0–100 cm increased linearly with the C input from eucalyptus harvest residues. In the layer of 0–20 cm, the lowest soil C retention rate was 0.23 Mg ha−1 year−1, in the NR treatment, while in the AR treatment, the retention rate was 0.68 Mg ha−1 year−1. In the 0–100 cm layer, the highest C retention rate was obtained in the AR (1.47 Mg ha−1 year−1). The residues showed a high humification coefficient (k1 = 0.23) and a high soil organic matter decomposition rate (k2 = 0.10). The carbon management index showed a close relationship with the C input and tree diameter at breast height. [ABSTRACT FROM AUTHOR]

Land-use systems (LUSs) and soil types (STs) are strongly related to factors that influence soil degradation and carbon (C) loss. However, the way in which land use and soil type affects the soil organic C (SOC) pools, and soil aggregation in the Sanjiang Plain, has not been thoroughly investigated. Therefore, this study aimed to investigate soil physic–ochemical properties, soil aggregates, and C management index (CMI) in three different LUSs (grassland, dryland, and paddy field) under two STs (meadow soil and albic soil) of the Sanjiang Plain in northeast China. A total of 60 composite soil samples were collected for laboratory analyses. The results were as follows: soil properties were affected by LUS and ST, especially soil chemical properties; ST had no significant effect on soil aggregates but significantly affected its SOC content, while LUS had a significant effect on soil aggregates (p < 0.01), except for small macro-aggregates (2–0.25 mm); the mean weight diameter (MWD) and SOC in meadow soil was significantly different under different land uses, with grassland being the highest and dryland the lowest. However, there was no significant difference in albic soil. The heterogeneity of grassland, dryland, and paddy field showed that different LUSs had particular effects on SOC and its active components because LUS had significant effects on C pool index (CPI) and CMI, but ST and its interaction had no significant effects on CPI and CMI. Overall, the results showed that LUS was an important factor affecting CMI in the Sanjiang Plain, rather than ST, and the paddy field CMI was optimal in the Sanjiang Plain. [ABSTRACT FROM AUTHOR]

Soil organic carbon (SOC) shapes carbon cycling and climate. Grassland degradation has greatly reduced the SOC of these biomes. However, vegetation restoration is effective at improving the SOC of degraded grasslands, the sustainability of the outcomes of which is unclear. Therefore, we studied the effects of vegetation restoration on SOC and its stability in perspective of three restoration practices (i.e. Hippophae rhamnoides Linn., Elymus nutans Griseb., Avena nuda, and their combinations) in Zoige, a climatically sensitive area located at the eastern Qinghai‐Tibet Plateau. Topsoil samples (0–10 cm) were collected within each restoration practice to analyze SOC and its fraction contents, soil aggregates, and aggregate‐associated SOC content. Results showed that SOC in the control (CK) was 2.77 g kg−1, and vegetation restoration increased the SOC contents by 10.12, 73.00, and 15.81%, respectively. Vegetation restoration significantly increased the easily oxidizable carbon (EOC) and decreased recalcitrant organic carbon (ROC), highlighting different responses of SOC fractions to vegetation restoration. Soil macroaggregate was 8.74% in CK, which was significantly lower than that after vegetation restoration (57.08–81.01%). Vegetation restoration had no impact on non‐aggregated silt + clay fraction‐associated SOC and significantly increased macroaggregate‐associated SOC content, which was the major contributor of total SOC. These findings suggest that vegetation restoration may affect SOC stability by increasing SOC and EOC, decreasing ROC, and changing the compositions of aggregates and aggregate‐associated SOC. However, our study was conducted 3 years after vegetation restoration, which maybe too short of a period to accurately determine SOC stability. [ABSTRACT FROM AUTHOR]

Depending on the type of agricultural use and applied crop rotation, soil organic carbon accumulation may depend, which can lead to less CO2 fixation in the global carbon cycle. Less is known about organic carbon emissions in different crop production systems (cereals, grasses) using different agrotechnologies. There is a lack of more detailed studies on the influence of carbon content in the soil on plant productivity, as well as the links between the physical properties of the soil and the absorption, viability, and emission of greenhouse gases (GHG) from mineral fertilizers. The aim of this study is to estimate the long-term effect of soil organic carbon sequestration potential in different crop rotations. The greatest potential for organic carbon sequestration is Norfolk-type crop rotation, where crops that reduce soil fertility are replaced by crops that increase soil fertility every year. Soil carbon sequestration potential was significantly higher (46.72%) compared with continuous black fallow and significantly higher from 27.70 to 14.19% compared with field with row crops and cereal crop rotations, respectively, intensive crop rotation saturated with intermediate crops. In terms of carbon sequestration, it is most effective to keep perennial grasses for one year while the soil is still full of undecomposed cereal straw from the previous crop. Black fallow without manure fertilization, compared to crop rotation, reduces the amount of organic carbon in the soil up to two times, the carbon management index by 2–5 times, and poses the greatest risk to the potential of carbon sequestration in agriculture.

Although agro-geotextile (AGT) emplacement shows potential to mitigate soil loss and, thus, increase carbon sequestration, comprehensive information is scanty on the impact of using agro-geotextiles on soil organic carbon (SOC) sequestration, aggregate-associated C, and soil loss in the foothills of the Indian Himalayan Region. We evaluated the impacts of Arundo donax AGT in different configurations on SOC sequestration, aggregate stability, and carbon management index (CMI) since 2017 under maize-based cropping systems on a 4% land slope, where eight treatment procedures were adopted. The results revealed that A. donax placement at 0.5-m vertical-interval pea–wheat (M + AD10G0.5-P-W) treatment had ∼23% increase in SOC stock (27.87 Mg·ha−1) compared to the maize–wheat (M-W) system in the 0–30-cm soil layer. M + AD10G0.5-P-W and maize–pea–wheat treatments under bench terracing (M-P-W)BT had similar impacts on SOC stocks in that layer after 5 years of cropping. The total SOC values in bulk soils, macroaggregates, and microaggregates were ∼24, 20, and 31% higher, respectively, in plots under M + AD10G0.5-P-W treatment than M-W in the topsoil (0–5 cm). The inclusion of post-rainy season vegetable pea in the maize–wheat cropping system, along with AGT application and crop residue management, generated additional biomass and enhanced CMI by ∼60% in the plots under M + AD10G0.5-P-W treatment over M-W, although M + AD10G0.5-P-W and (M-P-W)BT had similar effects in the topsoil. In the 5–15-cm layer, there was no significant effect of soil conservation practices on CMI values. Under the M + AD10G0.5-P-W treatment, the annual mean soil loss decreased by ∼92% over M-W treatment. We observed that CMI, proportion of macroaggregates, aggregate-associated C, labile C, total SOC concentration (thus, SOC accumulation rate), and mean annual C input were strongly correlated with the mean annual soil loss from 2017 to 2021. The study revealed that the emplacement of an A. donax mat and incorporation of a legume in a cropping system (M-W), conservation tillage, and crop residue retention not only prevented soil loss but also enhanced C sequestration compared to farmers’ practice (M-W) in the Indian Himalayas. The significance of this study is soil conservation, recycling of residues and weeds, and climate change adaptation and mitigation, as well as increasing farmers’ income.

Soil labile organic carbon (LOC) is a crucial component in carbon cycling in coastal wetlands and serves as an important indicator of SOC. Despite this, little is known about the stabilization of SOC and its LOC during mangrove development. The objective of our study was to quantify SOC and LOC in the soil at depths ranging from 0 to 100 cm across four sites, including a mudflat and three mangrove sites of varying ages (15-, 45-, and 80-yr old) were selected in Yingluo Bay, China. The concentration of SOC, POC (particulate organic carbon), DOC (dissolved organic carbon), MBC (microbial biomass carbon), and KMnO4-C (potassium permanganate-oxidizable carbon) were measured. The CMI (soil carbon management index) was also calculated to precisely and directly reflect the dynamic changes of soil carbon pools. Mangrove natural expansion showed a significant positive effect on both SOC and LOC. The concentration of KMnO4-C in the top 50 cm of soil layer showed a significant increase in three different mangrove forest sites. The POC, DOC and MBC were also significantly increased in response to mangrove development. The 80-yr old mangrove site had the highest SOC concentrations, LOC concentrations, soil carbon lability Index (LI) and CMI among all sites. These findings suggested that the development of mangroves increases soil organic carbon fractions through vegetation production and enhances long-term carbon sequestration rates by expanding soil labile carbon pools. As a management option, promoting the natural expansion of mangroves can maximize the sequestration potential of soil organic carbon.

The growing global population and increasing demand for agricultural products have exerted significant pressure on agricultural systems. As a result, soil organic matter depletion and degradation have become prevalent issues, including in regions such as South Bohemia, Czech Republic, where conventional farming practices are predominant. Soil organic matter (SOM) plays a critical role in soil health, crop productivity, and the sustainability of agricultural systems, with changes occurring in both the total and labile fractions of the organic matter pools. However, changes in the total soil organic matter carbon pool (TOC) resulting from agricultural practices occur gradually and may become evident only after several years, posing challenges for timely management adjustments. Therefore, the identification of early indicators of SOM dynamics is crucial for implementing prompt corrective actions. The aim of this study was to evaluate the effects of sustainable management practices, such as cultivated crops (Pisum sativum and Lupinus albus), selected entomopathogenic and myco parasitic fungi (MEHA) (Trichoderma virens and Metarhizium brunneum), and lactic acid bacteria (LAB) on the labile fraction of the SOM pool (CLSOM) and identify potential early indicators. Our findings demonstrated that the type of crop and applied microorganisms (treatments) significantly affected the CLSOM in peas, and the crop growth stages affected the TOC in both pea and lupin. Growth stages also showed an impact on the CLSOM in lupin. Moreover, in both crops, the change in CLSOM correlated with changes in the SOM oxidation rate constant (k), carbon lability index (LI), carbon management index (CMI), and carbon enrichment ratio (ER). Conversely, changes in the TOC did not exhibit significant correlations, except for LI and CMI, which showed a positive correlation with the TOC in peas (p < 0.05). Furthermore, the separate application of MEHA and LAB on seeds or leaves resulted in increased SOM carbon pools compared with the combined application. The application of these beneficial microorganisms in pea and lupin crops showed potential in maintaining or increasing CLSOM, which can be assessed early through indicators such as k, LI, CMI, and ER. Contributing to the development of sustainable soil management strategies, future research should further investigate different crops and microorganisms—and the mechanisms underlying their observed relationships—and explore additional early indicators to refine and optimize sustainable agricultural practices. [ABSTRACT FROM AUTHOR]

Current study was conducted to evaluate the effect of important land uses and soil depth on soil organic carbon pools viz. total organic carbon, Walkley and black carbon, labile organic carbon, particulate organic carbon, microbial biomass carbon and carbon management index (CMI) in the north Western Himalayas, India. Soil samples from five different land uses viz. forest, pasture, apple, saffron and paddy-oilseed were collected up to a depth of 1 m (0-30,30-60,60-90 cm). The results revealed that regardless of soil depth, all the carbon pools differed significantly (p < 0.05) among studied land use systems with maximum values observed under forest soils and lowest under paddy-oilseed soils. Further, upon evaluating the impact of soil depth, a significant (p < 0.05) decline and variation in all the carbon pools was observed with maximum values recorded in surface (0-30 cm) soils and least in sub-surface (60-90 cm) layers. CMI was higher in forest soils and lowest in paddy-oilseed. From regression analysis, a positive significant association (high R-squared values) between CMI and soil organic carbon pools was also observed at all three depths. Therefore, land use changes and soil depth had a significant impact on soil organic carbon pools and eventually on CMI, which is used as deterioration indicator or soil carbon rehabilitation that influences the universal goal of sustainability in the long run. [ABSTRACT FROM AUTHOR]

Manure nutrient management can affect soil carbon (C) and nitrogen (N) fractions. The objective of this study was to determine the effects of long-term manure and mineral fertilizer applications on C and N fractions. This study was conducted for 11 years under corn and soybean rotation. The study rates included low manure (LM (4,194 kg ha−1), based on the crop's phosphorus (P) requirement), medium manure (MM (8,081 kg ha−1), based on the crop's N requirement), high manure (HM (16,162 kg ha−1), two times the rate of MM), medium fertilizer (MF (204 kg N ha−1), recommended), high fertilizer (HF (224 kg N ha−1), high), and control. Soil samples were collected to measure C and N fractions. HM recorded higher particulate C (8%) at 0–10 cm and higher dissolved C (26%) at 10–20 cm compared to LM. All manure rates had higher permanganate oxidizable C compared to mineral fertilizer rates. Carbon management index was higher under MM compared to the HF (17%) and MF (33%). This study suggests that manure application (16,162 kg ha−1 rate and even 8,081 kg ha−1 and 4,194 kg ha−1 rates in some cases) can enhance C and N pools compared to mineral fertilizer application. [ABSTRACT FROM AUTHOR]

Current study was conducted to evaluate the effect of important land uses and soil depth on soil organic carbon pools viz. total organic carbon, Walkley and black carbon, labile organic carbon, particulate organic carbon, microbial biomass carbon and carbon management index (CMI) in the north Western Himalayas, India. Soil samples from five different land uses viz. forest, pasture, apple, saffron and paddy-oilseed were collected up to a depth of 1 m (0–30, 30–60, 60–90 cm). The results revealed that regardless of soil depth, all the carbon pools differed significantly (p

The southwest region of the Goiás state, Brazil, is suitable for several agricultural activities, even in more fragile soils such as Typic Quartzipsamments. This study aimed to evaluate the carbon stocks and lability of a Typic Quartzipsamment under land use and management systems in southwestern Goiás. The experiment was conducted in a completely randomized design and consisted of areas subjected to five land use and management systems [native Cerrado vegetation (Brazilian Savanna), pasture under intensive grazing, pasture under extensive grazing, soybean and maize rotation, and eucalyptus]. Soil samples were collected at the 0-0.1 and 0.1-0.2 m layers. The land use and management systems affected the carbon stocks and quality. In the 0-0.2 m layer, the carbon stocks ranged between 15.9 and 29.2 Mg ha-1. The areas with eucalyptus and under intensive grazing promoted increases in the carbon stocks that ranged between 72 and 84 %, when compared to the areas with Cerrado vegetation and soybean and maize rotation. The carbon contents in the F1, F2 and F4 fractions were higher in the areas with eucalyptus and under intensive grazing. In the 0-0.1 m soil layer, the areas with eucalyptus and under intensive grazing had an increase in the carbon management index by 33 and 36 %, respectively, when compared to the reference area with native Cerrado vegetation.

Dry stable aggregates, soil organic carbon (SOC) stocks, and aggregate‐associated carbon are measured as vital factors for preserving soil quality. Different land use systems strongly impacts the services of the ecosystem to influence soil degradation and loss of carbon. Little is known about the dry aggregates stability and SOC stocks in the dry, semiarid region of Balochistan, Pakistan or how these resist land degradation. This study aimed to assess the impact of several land‐use systems on SOC stocks, the distribution of soil aggregates, and the carbon management index. The treatments consisted of five land‐use systems, namely, grassland, cropland, fallow land, forests, and vegetation, typically prevail in the region. Three layers of soil were used to sample it (0–15, 15–30, and 30–45 cm) and sieved into five aggregate classes (>8, 8–5, 5–2, 2–0.25, and <0.25 mm). The grasslands had significant higher SOC concentrations (12.83 g kg−1), SOC stocks (19.44 mg ha−1), liability index (0.89 g kg−1), nonlabile C (9.56 g kg−1), labile C (0.35 g kg−1), carbon management index (204.6), and easily oxidizable carbon (3.27 g kg−1), when compared with fallow land. Moreover, grassland and forestland soils contained larger macroaggregates (>0.25 mm), although the fallow land‐use system had a higher degree of micro aggregates (<0.25 mm). We found strong relationship of soil SOC with SOC concentration of soil aggregates and other labile fractions of carbon. Therefore, grassland and forestland promotes the aggregate‐associated SOC and carbon management index by enhancing the soil aggregation and is therefore a possible managing option to develop the SOC sequestration potential of eroded dry soils. [ABSTRACT FROM AUTHOR]

This study is aimed at evaluating C and N stocks in fractions of soil organic matter (SOM) in an area of bauxite mining under recovery with tree species. We have analyzed the long-term recovery of C and N stocks of organic matter fractions from five types of forest cover (Eucalyptus, Anadenanthera peregrina, mixed plantation of 16 native species, a mined area without vegetation cover as a control site, and a natural forest cover as a reference site). The total organic C (TOC) and N (TN) stocks and also organic matter fractions, particulate organic matter (POM), mineral-associated organic matter (MAOM), microbial biomass (MB), and labile C (LC), were determined, as well as the C/N ratio and the carbon management index (CMI). Although the stocks of TOC and LC, CMI, and MB did not differ between the types of forest cover in the 0–60 cm layer, they were lower than the values in the native forest. Forest cover increases the stocks of TOC, LC, MB, and CMI in the area of bauxite mining compared to the control site. In addition, we found that the TOC C and TN stocks and also SOM fractions (LC, C-MAOM, C-POM, N-MAOM, and N-POM) are positively correlated (r ≥ 0.71 for all cases) with volume of roots larger than 2 mm. Therefore, Eucalyptus, A. peregrina, and a mixed of 16 native trees contribute for restoring stocks of soil C and N following bauxite mining in the Brazilian Atlantic Forest. [ABSTRACT FROM AUTHOR]

Permanganate oxidized organic carbon (POXC) is used as a standardized methodology for the determination of labile carbon due to its correlation with other soil labile fractions, high accuracy, and practical application. The main goals of this study were to assess labile carbon in the soil across different types of land use and establish the Carbon Management Index (CMI), which is a numerical index that evaluates the carbon status of soil in a given area and is derived from the outcomes of POXC analysis. The study was carried out in the Bukhmurun soum of Uvs province. Soil samples were collected from riverbeds, pastures, and forests at a depth of 0-20 and 20-40 cm, and analyzed for the physical and chemical properties of the soil following the standard methods, and labile carbon was determined using international methods in the Soil Laboratory of the Institute of Geography and Geoecology. According to the results, soil organic carbon (SOC) was detected in all samples and ranged between 9.4 and 73.2 g kg-1, with the highest value in forest soil and the lowest value in grassland soil. It was found that the POXC had a strong correlation (R2=0.62) with SOC. POXC exhibited a similar pattern as the SOC, it was highest in the forest soil, followed by alluvial and grassland soils. The percentage of the POXC ranged from 1.7% to 20% of the SOC. The CMI value varied with the depth. At the depth of 0-20 cm, it was 216 in forest soil, 192 in alluvial soil, and 83 in pasture soil, whereas, at the depth of 20-40 cm, it was 156 in forest soil, 129 in alluvial soil, and 73 in pasture soil. The CMI provides an assessment of how effectively soils are sequestered and storing carbon, as well as how susceptible they are to carbon loss. POXC is a relatively new and inexpensive method for determining labile organic carbon that is less harmful and can be executed without the need for special equipment such as centrifuges. This method of POXC determination is of practical importance in predicting soil quality or determining soil quality by the color change of the permanganate solution after soil-solution interaction. It is deemed prudent to employ this method further for the comprehensive assessment of soil quality. [ABSTRACT FROM AUTHOR]

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The overapplication of mineral nitrogen (N) fertilizer has become a scientific problem to be solved in the North China Plain; meanwhile, most organic manure cannot be recycled into the soil. To make full use of organic manure and decrease the applied rate of mineral N fertilizer, a four-year fertilization experiment was carried out to assess the effects of substituting mineral fertilizer with organic manure on soil organic carbon (SOC), labile organic carbon (LOC), stable organic carbon (UOC), microbial biomass carbon (MBC), and soil enzymatic activity. There were six treatments including unfertilized control (CK); mineral fertilizer without organic manure (FR); and mineral nitrogen substituted by organic manure at 20%, 40%, 60%, and 80% (FM1, FM2, FM3, and FM4), respectively. The results showed that SOC, UOC, and LOC were significantly increased by 13.30~40.56%, 41.10~121.92%, and 4.91~15.57% with increasing amounts of organic manure, respectively. Adding organic manure also enhanced urease, catalase, sucrase, and cellulase activities as well as MBC in surface soil (0–20 cm). The present study revealed the activities of urease, catalase, sucrase, and cellulase were closely related to SOC and its components. Following organic manure application, MBC and enzymatic activities had active effects in enhancing LOC and UOC sequestration based on path analyses. Additionally, organic manure increased SOC by direct and indirect enhancement of UOC and LOC, respectively, and improved SOC sequestration as compared to FR treatment. Finally, the study revealed that SOC quantity and quality were both significantly improved by combined application of mineral fertilizer and organic manure, and this effect was enhanced with the increase of organic manure application. Considering the improvements in soil properties and grain yields, substituting mineral fertilizer with organic manure might be a promising alternative in the North China Plain. [ABSTRACT FROM AUTHOR]

This study quantified the C content of the chemical and physical fractions of SOM in different management systems in an Argisoil of sandy texture. The study was carried out in a reference area of Native Forest (NF), and in three managed areas: Permanent Pasture (PP), No-Tillage System (NTS) and an area of Private Natural Heritage Reserve (PNHR) in the process of natural regeneration. Soil samples were collected in the layers 0.0-0.05, 0.05-0.10 and 0.10-0.20 m. We assessed the soil density (Sd), total organic carbon (TOC) content, chemical fractionation of SOM with determination of the C contents of the fulvic acids (FA), humic acids (HA) and humin (HUM), with subsequent calculations of the HA/FA ratios, AE/HUM, stock (StockC), physical granulometric fractionation and determination of C contents of particulate organic matter (C-POM) and carbon management index (CMI). Higher TOC contents were observed for the NF area. The C-HA and C-HUM contents were higher in the NF and NTS. NF showed higher C-POM levels in all layers evaluated. For the C-MOM, the NTS area was superior to the other managed areas. The managed areas had lower StockPOM values than the NF. The managed areas had lower CMI values in relation to NF. The NTS area showed that, even in crop succession, it contributes to the improvement of the soil organic fraction over the adoption time. On the other hand, the areas of PP and PNHR showed that inadequate management favors the reduction of edaphic quality.

Commercial cultivation of the Macauba palm is growing due to its agro-energy potential. This study quantified carbon stock in two macauba plantations (4.8 and 9.0 years old), considering carbon stored in soil and biomass. We assessed total organic carbon (TOC) stocks in labile (EOC and LF-C) and non-labile (NL-C) soil fractions, comparing these with a forest regenerating for over 30 years. Soil samples were collected within the palm plantation (rows and inter-rows) and the forest area at five depths (0–10, 10–20, 20–40, 40–60, and 60–100 cm). The impact of plantation age and sampling position on TOC stocks and organic matter fractions across different soil layers (0–100 cm) was assessed. The Carbon Management Index (CMI) was calculated to evaluate carbon recovery. Plantation age and sampling position influenced soil TOC stocks across all depths up to 1 m. Higher TOC and NL-C soil stocks were observed in the older plantation (9.0 years) and inter-row. EOC and LF-C fractions varied by soil layer. The inter-row region of the 9.0-year-old plantation exhibited higher carbon recovery based on the CMI. Over 4.2 years of palm cultivation (between 4.8 and 9.0 years), carbon accumulation in biomass and soil reached 75.36 Mg C ha−1. These findings underscore the potential of commercial macauba plantations to enhance soil carbon stocks rapidly, particularly in inter-row areas. Plantations younger than a decade surpassed the soil carbon stock of a forest regenerating for over 30 years, highlighting significant environmental benefits of macauba cultivation, including soil and biomass carbon sequestration. • The age of macauba cultivation and the sampling position determine the soil organic carbon stocks up to a depth of 1 m. • Macauba cultivation can sequester more soil carbon in under a decade than a forest with 30+ years of natural regeneration. • The commercial cultivation of adult macauba can increase carbon accumulation in biomass and soil by 17.94 Mg C ha−1 year−1. [ABSTRACT FROM AUTHOR]

There has been limited research on the effect of eucalyptus harvest residue management on soil organic carbon (SOC) in subtropical environments. This research evaluated the effect on soil C indices of the following eucalyptus harvest residue managements: AR, with all forest remnants left on the soil; NB, where bark was removed; NBr, in which branches were removed; NR, which removed all residues; and NRs, which is same as NR but also used a shade net to prevent the litter from the new plantation from reaching the soil surface. C stocks within the soil depths of 0–20 cm and 0–100 cm increased linearly with the C input from eucalyptus harvest residues. In the layer of 0–20 cm, the lowest soil C retention rate was 0.23 Mg ha−1 year−1, in the NR treatment, while in the AR treatment, the retention rate was 0.68 Mg ha−1 year−1. In the 0–100 cm layer, the highest C retention rate was obtained in the AR (1.47 Mg ha−1 year−1). The residues showed a high humification coefficient (k1 = 0.23) and a high soil organic matter decomposition rate (k2 = 0.10). The carbon management index showed a close relationship with the C input and tree diameter at breast height.

Land-use systems (LUSs) and soil types (STs) are strongly related to factors that influence soil degradation and carbon (C) loss. However, the way in which land use and soil type affects the soil organic C (SOC) pools, and soil aggregation in the Sanjiang Plain, has not been thoroughly investigated. Therefore, this study aimed to investigate soil physic–ochemical properties, soil aggregates, and C management index (CMI) in three different LUSs (grassland, dryland, and paddy field) under two STs (meadow soil and albic soil) of the Sanjiang Plain in northeast China. A total of 60 composite soil samples were collected for laboratory analyses. The results were as follows: soil properties were affected by LUS and ST, especially soil chemical properties; ST had no significant effect on soil aggregates but significantly affected its SOC content, while LUS had a significant effect on soil aggregates (p < 0.01), except for small macro-aggregates (2–0.25 mm); the mean weight diameter (MWD) and SOC in meadow soil was significantly different under different land uses, with grassland being the highest and dryland the lowest. However, there was no significant difference in albic soil. The heterogeneity of grassland, dryland, and paddy field showed that different LUSs had particular effects on SOC and its active components because LUS had significant effects on C pool index (CPI) and CMI, but ST and its interaction had no significant effects on CPI and CMI. Overall, the results showed that LUS was an important factor affecting CMI in the Sanjiang Plain, rather than ST, and the paddy field CMI was optimal in the Sanjiang Plain.

Soil erosion threatens the sustainable intensification of food systems among smallholder farmers in arid and semi-arid lands (ASALs). Intensifying adoption of soil mitigation and rehabilitation measures is thus needed urgently in these ASALs, but scaling up these measures depends on scientific evidence of their contributions to key components of sustainable intensification such as soil organic carbon. However, there is no information on how existing mitigation and rehabilitation measures influence soil carbon fractions and carbon management indices in ASALs. This study evaluated the influence of soil erosion mitigation and rehabilitation measures on soil carbon fractions and management indices in Arenic Lixisols of semi-arid environments in West Pokot County, Kenya. We evaluated different vegetation types (maize-beans intercrop and pastures) with and without two locally developed terrace designs for soil conservation (Fanya Juu and Fanya Chini). Combining terracing with annual cropping significantly increased total organic carbon (TOC). The highest TOC (13 g C kg−1) was recorded in pasturelands with terraces while degraded land with no intervention was found to have the lowest TOC (6.0 g C kg−1). Terraced farms with longer residence time (>4 years old) had significantly higher organic carbon than (

Food security and environmental health are directly linked with soil carbon (C). Soil C plays a crucial role in securing food and livelihood security for the Himalayan population besides maintaining the ecological balance in the Indian Himalayas. However, soil C is being severely depleted due to anthropogenic activities. It is well known that land use management strongly impacted the soil organic carbon (SOC) dynamics and also regulates the atmospheric C chemistry. Different types of cultivation practices, i.e., forest, plantations, and crops in the Kashmir Himalayas, India, has different abilities to conserve SOC and emit C in the form of carbon dioxide (CO2). Hence, five prominent land use systems (LUC) (e.g., natural forest, natural grassland, maize-field-converted from the forest, plantation, and paddy crop) of Kashmir Himalaya were evaluated to conserve SOC, reduce C emissions, improve soil properties and develop understanding SOC pools and its fractions variations under different land use management practices. The results revealed that at 0–20 cm and 20–40 cm profile, the soil under natural forest conserved the highest total organic carbon (TOC, 24.24 g kg−1 and 18.76 g kg−1), Walkley-black carbon (WBC, 18.23 g kg−1 and 14.10 g kg−1), very-labile-carbon (VLC, 8.65 g kg−1, and 6.30 g kg−1), labile-carbon (LC, 3.58 g kg−1 and 3.14 g kg−1), less-labile-carbon (VLC, 2.59 g kg−1, and 2.00 g kg−1), non-labile-carbon (NLC, 3.41 g kg−1 and 2.66 g kg-1), TOC stock (45.88 Mg ha−1 and 41.16 Mg ha−1), WBC stock (34.50 Mg ha−1 and 30.94 Mg ha−1), active carbon pools (AC, 23.14 Mg ha−1 and 20.66 Mg ha−1), passive carbon pools (PC, 11.40 Mg ha−1 and 10.26 Mg ha−1) and carbon management index (CMI, 100), followed by the natural grassland. However, the lowest C storage was reported in paddy cropland. The soils under natural forest and natural grassland systems had a greater amount of VLC, LC, LLC, and NLC fraction than other land uses at both depths. On the other hand, maize-field-converted-from-forest-land-use soils had a higher proportion of NLC fraction than paddy soils; nonetheless, the NLC pool was maximum in natural forest soil. LUS based on forest crops maintains more SOC, while agricultural crops, such as paddy and maize, tend to emit more C in the Himalayan region. Therefore, research findings suggest that SOC under the Kashmir Himalayas can be protected by adopting suitable LUS, namely forest soil protection, and by placing some areas under plantations. The areas under the rice and maize fields emit more CO2, hence, there is a need to adopt the conservation effective measure to conserve the SOC without compromising farm productivity.

The increased land-use change (LUC) from native lands to other land use at the Conoor region of western ghats in Tamil Nadu has severely declined soil carbon concentration. Therefore to quantify this decline, Carbon Management Index (CMI) was worked out under major land uses {(Forest (FOR), cropland (CRP), tea plantation (TEA)} using total organic carbon (TOC) and carbon pools under varying degrees of lability {a) NLC (non-labile carbon) b) VLC (very labile carbon) c) LC (labile carbon) d) LLC (less labile carbon)}. Results portray that the carbon pools were significantly (p < 0.05) higher in FOR than in TEA and CRP. The contribution of active pools {(very labile carbon (VLC) and labile carbon (LC)} towards TOC was higher in TEA and CRP, whereas in FOR, the passive pool {(less labile carbon (LLC) and non-labile carbon (NLC)} was higher. TOC (0-45 cm) was concentrated on the surface soils of FOR (32.88 g kg-1), CRP (11.87 g kg-1) and TEA (18.84 g kg-1) and it gradually declined with the increase in depth. The decline in TOC was maximum between 0 -- 15 and 15 -- 30 cm depth in CRP (30.62%) and FOR (22.17%), whereas it was maximum (37.16%) between 15-30 and 30 -45 cm depth in TEA. Therefore, LUC spotlights the degradation of carbon pools and its extent was quantified using the carbon management index (CMI). The CMI (0 -- 45 cm) recorded at CRP (12.93) and TEA (32.62) signals the need for an implementation of carbon management strategies at Conoor to keep the soils alive and protect biodiversity. [ABSTRACT FROM AUTHOR]

Land uses are pivotal in global carbon cycles. The native forest lands possess a greater potential to sequester higher carbon, which can directly address soil quality and climate change problems. Unfortunately, the rapid conversion of forests to other land use over the past few decades has significantly declined the concentration of carbon in the soils. Therefore, in order to estimate the impact of land-use change (LUC) on soil carbon status, this present study was attempted under major ecosystems (Forest (FOR), cropland (CRP), tea plantation (TEA)) of Conoor. Results from findings revealed that total organic carbon (TOC) concentration and carbon pools were significantly (p<0.05) higher in FOR than in CRP and TEA. TOC (0-45 cm) recorded in FOR, CRP and TEA was 32.88, 11.87 and 18.84 g kg-1 and it decreased along the depth increment. Carbon stock (t ha-1) in FOR, CRP and TEA (0-45cm) was 68.10, 26.04, 42.42. Microbial biomass carbon (MBC) was higher in FOR (283.08 mg kg-1) followed by TEA (94.64 mg kg-1) and CRP (76.22 mg kg-1). The microbial biomass nitrogen (MBN) followed; FOR > TEA > CRP. These results clearly indicate that the LUC has inflicted a greater impact on soil carbon status and its extent was quantified using the land degradation index (LDI). The LDI (0-45 cm) recorded in CRP (-38.65) and TEA (-61.75) signals the need for immediate implementation of carbon management strategies in the CRP and TEA ecosystem to keep the soils of Conoor alive and prevent land degradation. [ABSTRACT FROM AUTHOR]

Copyright of Revista Ambiente e Água is the property of Revista Ambiente e Agua and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Agroforestry systems (AFS) are economically viable and provide diverse ecosystem services. We studied the long-term effects of tree-based AFS on carbon and nitrogen pools in Punjab, India. The selected systems were poplar with fodder–wheat rotation (T1), eucalyptus with fodder–wheat rotation (T2), sole fodder–wheat rotation (T3), poplar with citrus (kinnow) (T4), eucalyptus with citrus (T5), sole citrus (T6) and fallow land (T7). At the 0–15 cm soil depth, T1 and T2 had 87.9 and 70.6% higher soil organic carbon (SOC), respectively, than T3, while T4 and T5 had 37.4 and 30.2% higher SOC, respectively, than T6. At all soil depths, SOC was lowest under fallow land and decreased with depth. The soil carbon pools (very labile, labile, less labile and recalcitrant carbon) were highly positively correlated with SOC and were higher in T1 and T2 than in other land-use systems. Water-soluble carbon, microbial biomass carbon, total N, ammonium N and nitrate N were highest in T1 and decreased with depth. Carbon management index was significantly higher in T1 and T2 than other systems. Therefore, poplar- and eucalyptus-based AFS with fodder–wheat rotation were more efficient in improving soil carbon and nitrogen status along with sustainability of the systems.

The growing global population and increasing demand for agricultural products have exerted significant pressure on agricultural systems. As a result, soil organic matter depletion and degradation have become prevalent issues, including in regions such as South Bohemia, Czech Republic, where conventional farming practices are predominant. Soil organic matter (SOM) plays a critical role in soil health, crop productivity, and the sustainability of agricultural systems, with changes occurring in both the total and labile fractions of the organic matter pools. However, changes in the total soil organic matter carbon pool (TOC) resulting from agricultural practices occur gradually and may become evident only after several years, posing challenges for timely management adjustments. Therefore, the identification of early indicators of SOM dynamics is crucial for implementing prompt corrective actions. The aim of this study was to evaluate the effects of sustainable management practices, such as cultivated crops (Pisum sativum and Lupinus albus), selected entomopathogenic and myco parasitic fungi (MEHA) (Trichoderma virens and Metarhizium brunneum), and lactic acid bacteria (LAB) on the labile fraction of the SOM pool (CLSOM) and identify potential early indicators. Our findings demonstrated that the type of crop and applied microorganisms (treatments) significantly affected the CLSOM in peas, and the crop growth stages affected the TOC in both pea and lupin. Growth stages also showed an impact on the CLSOM in lupin. Moreover, in both crops, the change in CLSOM correlated with changes in the SOM oxidation rate constant (k), carbon lability index (LI), carbon management index (CMI), and carbon enrichment ratio (ER). Conversely, changes in the TOC did not exhibit significant correlations, except for LI and CMI, which showed a positive correlation with the TOC in peas (p < 0.05). Furthermore, the separate application of MEHA and LAB on seeds or leaves resulted in increased SOM carbon pools compared with the combined application. The application of these beneficial microorganisms in pea and lupin crops showed potential in maintaining or increasing CLSOM, which can be assessed early through indicators such as k, LI, CMI, and ER. Contributing to the development of sustainable soil management strategies, future research should further investigate different crops and microorganisms—and the mechanisms underlying their observed relationships—and explore additional early indicators to refine and optimize sustainable agricultural practices.

A long-term experiment was conducted for 8 years to assess the impact of imbalance and balance fertilization based on soil test-based nutrient management practices on different carbon fractions, carbon (C) stocks, sequestration, C indexes and soil quality under Jute-rice-lentil cropping system in subtropical India. The 10 treatments were laid out in a randomized block design. Treatments included the use of farm yard manure (FYM), bio-inoculants and inorganic fertilizers at different rates and combinations. Results revealed that conjunctive use of inorganic fertilizer based on soil test and targeted yield approach, organic manure (FYM) and bio-inoculants was found to be superior in comparison to other nutrient management practices in terms of sustaining crop productivity and enhancing soil quality. Integrated soil test-based nutrient management increased total soil organic carbon (TSOC) by 16.9% compared to initial values and permanganate oxidizable C (KMnO4-C) to the extent of 26.2% over the control. Soil microbial biomass carbon (SMBC) (374 μg g−1 soil) and microbial quotient (3.3%) were also found highest in integrated soil test-based nutrient management treatment. SMBC and KMnO4-C constituted to the TSOC to the extent of 1.7 to 3.34% and 12.6 to 13.8%. The highest carbon management index value (129) was obtained in the treatment with integrated application of balanced fertilizes based on soil test and targeted yield, indicating that this system has better soil quality than the other management systems. C sequestration rate in the study varied from 0.015 to 0.16 Mg C ha−1 yr−1 under different treatments. [ABSTRACT FROM AUTHOR]

Moso bamboo (Phyllostachys pubescens) has an extremely fast growth rate and major carbon sequestration potential. However, little information is available on the dynamics of soil C accumulation and fungi communities related to different management practices. Here, we investigated changes in the soil organic carbon (SOC) fractions and fungal communities of a Moso bamboo plantation under three different management practices (M0: undisturbed; M1: extensively managed; and M2: intensively managed). Compared with M0, SOC levels were reduced by 41.2% and 71.5% in M1 and M2, respectively; furthermore, four SOC fractions (C1: very labile; C2: labile; C3: less labile; and C4: nonlabile) and the carbon management index (CMI) were also significantly reduced by plantation management. These practices further altered fungal communities, for example, by increasing Basidiomycota and Mortierellomycota, and by decreasing Ascomycota and Rozellomycota. Pyrenochaeta, Mortierella, Saitozyma, and Cladophialophora were identified as keystone taxa. Soil fungal communities were significantly related to the pH, NH4-N, AP, C3, and the C4 fractions of SOC. Random forest modeling identified soil C3 and Mortierella as the most important predictors of the CMI. Our results suggest that reducing human interference would be beneficial for fungal community improvement and C sequestration in Moso bamboo plantations. [ABSTRACT FROM AUTHOR]

To test the applicability of alternate land use systems for improving soil functionality in restored ecologies, soils were sampled from 0–15, 15–30 and 30–45 cm deep layers of Leucaena leucocephala (LL), Hardwickia binata (HB), Emblica officinalis (EO), Azadiracta indica (AI)‐based silviculture systems; Acacia nilotica‐based silvipasture systems (AN); and natural grassland (NG). These were compared with samples from fallow land (F). They were evaluated for their carbon management index (CMI), nutrient supply capacity (NSC), soil functionality (SF), ecorestoration efficiency (ERE) and 21‐day cumulative microbial respiration (CO2‐21) to assess their applicability in semiarid India. Soil functionality and functional diversity as impacted by restoration have remained largely overlooked. The LL had ~12, 7 and 11% higher CMI than fallow in sampled soil layers. ERE of LL was ~ 55, 65 and 79% higher than fallow land in sampled soil layers, respectively. However, ERE in surface layer was poorer than subsequent soil layers for all systems. The LL, HB and AN improved NSC and SF by: a) ~ 2.5‐, 2.2‐ and 1.6‐times; and b) 9.3‐, 5.3‐ and 5.1‐times over fallow land in the surface soil layer. A similar trend was observed for SF in lower layers. However, the topsoil layer had >16% mean SF values than subsequent layers. LL, HB and AN systems had ~4.2‐, 2.3‐ and 1.9‐times higher CO2‐21 than fallow land in the top layer. CO2‐21 was positively correlated with NSC and SF but could not predict ERE well. Hence, legume tree‐based restoration tactics might be useful for improving land restoration and soil functionality in semiarid regions. [ABSTRACT FROM AUTHOR]

Soil carbon and its fractions are important in understanding the mechanism of soil carbon sequestration. The present study evaluated the impact of seven commercial bamboo species, viz., Bambusa balcooa, B. bambos, B. vulgaris, B. nutans, Dendrocalamus hamiltonii, D. stocksii, and D. strictus, on labile and non-labile carbon fractions. In the 0–15-cm layer, B. nutans had the highest very labile C (7.65 g kg−1) followed by B. vulgaris > B. balcooa > D. stocksii > D. hamiltonii > B. bambos > D. strictus > open. The active carbon pool was significantly low under the control plot (i.e. the open) indicating the positive influence of bamboo in soil C build-up in the top 0–15 cm soil layer. Amongst the different species of bamboo evaluated in this study, D. strictus accumulated the highest active C pool in 0–30-cm soil layer followed by B. vulgaris. Of the total organic C in the 0–30 cm soil depth, majority (55–60%) was contributed by the passive C pool comprising the less labile and the non-labile fraction of SOC. A high value of carbon stratification ratio (> 2) was observed for D. strictus, B. bambos, and D. hamiltonii which proves their potential for restoration of the degraded lands. The majority of bamboo species except for B. balcooa and D. stocksii showed a higher carbon management index than open systems, thereby indicating higher rates of soil C rehabilitation. Of the seven bamboo species, B. vulgaris, D. strictus, and B. nutans can be adopted for cultivation in the northwest Himalayas given their ability to positively impact the SOC and its fractions in both surface and sub-surface soil. [ABSTRACT FROM AUTHOR]

Soil organic C (SOC) pools have various stabilization mechanisms and turnover times, which change with depth and are highly influenced by land use. Total SOC (TOC), particulate organic carbon (POC), mineral-associated organic carbon (MOC), and carbon management index (CMI) were used as indicators to compare cropland with manure application (CM) and continuous pasture (CP) to a hardwood forest (HF) at soil 0–10 and 10–25 cm depths. Land use, depth, and their interactions had significant influences on TOC, POC, MOC, MOC/TOC ratio, and CMI except for land use main effect on TOC. Compared to HF and CP soils, CM showed significantly larger POC (12.4 g kg−1) and smaller MOC (8.36 g kg−1) at 10–25 cm; CM had significantly smaller TOC (32.3 g kg−1) and MOC at 0–10 cm (11.81 g kg−1). CM soil at 10–25 cm had higher soil quality and SOC lability as indicated by a significantly larger CMI value (419.2), while CP soil had lower soil quality and SOC lability at 0–10 cm (83.7) and 10–25 cm (73.6) compared to HF soil. This study implied high sensitivity of cropland and pasture surface SOC to degrade under disturbance, which implies that better management strategies are still needed to improve soil quality for these agricultural systems. [ABSTRACT FROM AUTHOR]

Agroforestry systems (AFS) are economically viable and provide diverse ecosystem services. We studied the long-term effects of tree-based AFS on carbon and nitrogen pools in Punjab, India. The selected systems were poplar with fodder–wheat rotation (T1), eucalyptus with fodder–wheat rotation (T2), sole fodder–wheat rotation (T3), poplar with citrus (kinnow) (T4), eucalyptus with citrus (T5), sole citrus (T6) and fallow land (T7). At the 0–15 cm soil depth, T1 and T2 had 87.9 and 70.6% higher soil organic carbon (SOC), respectively, than T3, while T4 and T5 had 37.4 and 30.2% higher SOC, respectively, than T6. At all soil depths, SOC was lowest under fallow land and decreased with depth. The soil carbon pools (very labile, labile, less labile and recalcitrant carbon) were highly positively correlated with SOC and were higher in T1 and T2 than in other land-use systems. Water-soluble carbon, microbial biomass carbon, total N, ammonium N and nitrate N were highest in T1 and decreased with depth. Carbon management index was significantly higher in T1 and T2 than other systems. Therefore, poplar- and eucalyptus-based AFS with fodder–wheat rotation were more efficient in improving soil carbon and nitrogen status along with sustainability of the systems. [ABSTRACT FROM AUTHOR]

Soil carbon (C) pools and biological indicator plays an important role in maintaining soil quality. Land use change from naturally undisturbed to intense cultivation had significant impact on C storage due to change in soil biological properties. The present study was conducted to understand the impact of land use change from the uncultivated to intensively cultivated soils under rice–wheat and cotton–wheat cropping system on labile and stable C pools, soil microbial and enzymatic activity, and a change in nutrient availability. The Olsen’s P concentration was significantly (p

Limited evidence is available on carbon sequestration potential of long-term integrated nutrient management (INM) versus mineral fertilization, when equivalent amounts of nutrients were added. Hence, this study was carried out to understand the impact of 60 years of INM with adjusted nutrient doses and mineral fertilization in an Alfisol in a maize (Zea mays L.)-wheat (Triticum aestivum L.) system on soil organic carbon (SOC) sequestration in surface (0–30 cm) and deep (30–60 cm) soil layers. Conventional tillage was done twice before sowing of both maize and wheat using a spade. In farmyard manure (FYM) and lime treated plots (FYMP'K'L: plots with nitrogen (N) applied in terms of FYM; additional dose of phosphorus (P) and potassium (K) and lime) total SOC concentration was nearly 83% higher than unfertilized control plots. The FYMP'K'L plots had ∼11% more total SOC concentration than plots treated with mineral fertilizer and lime (NPKL: recommended dose of N, P, K and lime) in the 0–30 cm soil layer. Labile C, including KMnO4-C, was more in plots with FYM than NPKL plots, whereas the recalcitrant C stock was more in NPKL than FYM treated plots. In the 0–60 cm soil layer, the labile C stock was highest in FYMP'K'L plots, but the recalcitrant C stock was highest in NPKL. Total SOC accumulation rate (over unfertilized control plots) was highest for FYMP'K'L plots (0.38 Mg ha−1 year−1) in the surface soil layer, whereas SOC sequestration rate was highest in NPKL plots (0.18 Mg ha−1 year−1) in the deep layer and in the 0–60 cm layer. Overall, although NPKL management practice had the highest C sequestration in the 0–60 cm layer, FYMP'K'L had the best CMI and labile C pools. Thus, resource poor farmers need not to use full doses of NPK and FYM for soil C management in the region.

The aim of the study was to determine the effect of soil management systems of Brunic Arenosols on total content of organic carbon and its fraction susceptible to oxidation in comparison with soils under forests. Samples for study were taken from the humus horizon at sites located in forests and soils from little mid-forest cultivated fields (hunting plots). The agrotechnical treatments increased the content of plant-available forms of P, K and Mg in the soils of most hunting plots in comparison to forest soils. In the arable horizon of the hunting plots there was found a varied total content of organic carbon and its fraction susceptible to oxidation. Cultivation of soil in hunting plots caused a decrease in content of total organic carbon as well as its labile and non-labile fraction. To evaluate the carbon transformation in the soil of the cultivated plots against the forest (reference soil), the Carbon Management Index (CMI) was used. The decay rate of soil organic matter in a natural forest was lower than in the agricultural fields. A long-term tillage of Brunic Arenosols contributed to the degradation of the pool of organic carbon in sandy-textured soil.

The changes in land use systems result in remarkable variations in SOC and its dynamics which subsequently govern soil biochemical processes, microbial and metabolic indices in soil. The detail understanding about the responses of different C pools to land uses is essential for maintaining the soil quality. The present study was undertaken in six rainfed land use systems of north eastern Punjab, India comprising of agriculture, horticulture, agri-horticulture, forestry, agroforestry and barren lands. The soil samples (0–15 cm) were collected and analyzed for soil carbon fractions and biochemical activities. The oxidisable carbon fractions i.e. very labile carbon, labile carbon, less labile carbon, recalcitrant carbon and total organic carbon contents in soil varied significantly from 0.09%–0.22%, 0.09%–0.23%, 0.02%–0.15%, 0.15%–0.72% and 0.83%–4.68%, respectively. The soil dehydrogenase activity, soil microbial biomass carbon, metabolic and microbial quotients showed significant variations and ranged from 5.4 –10.9 µg TPF g−1 soil h−1, 34.9 –184.5 µg g−1soil, 0.0011–0.0034, 45.0–195.5, respectively. Agri-horticulture and forestry system were observed to be best environment friendly and sustainable system in rainfed regions. Carbon management index (28.9%), metabolic potential (9.8%) and total organic carbon (5.4%) were three topmost soil quality indicators for soil health in rainfed land use systems.

The overapplication of mineral nitrogen (N) fertilizer has become a scientific problem to be solved in the North China Plain; meanwhile, most organic manure cannot be recycled into the soil. To make full use of organic manure and decrease the applied rate of mineral N fertilizer, a four-year fertilization experiment was carried out to assess the effects of substituting mineral fertilizer with organic manure on soil organic carbon (SOC), labile organic carbon (LOC), stable organic carbon (UOC), microbial biomass carbon (MBC), and soil enzymatic activity. There were six treatments including unfertilized control (CK); mineral fertilizer without organic manure (FR); and mineral nitrogen substituted by organic manure at 20%, 40%, 60%, and 80% (FM1, FM2, FM3, and FM4), respectively. The results showed that SOC, UOC, and LOC were significantly increased by 13.30~40.56%, 41.10~121.92%, and 4.91~15.57% with increasing amounts of organic manure, respectively. Adding organic manure also enhanced urease, catalase, sucrase, and cellulase activities as well as MBC in surface soil (0–20 cm). The present study revealed the activities of urease, catalase, sucrase, and cellulase were closely related to SOC and its components. Following organic manure application, MBC and enzymatic activities had active effects in enhancing LOC and UOC sequestration based on path analyses. Additionally, organic manure increased SOC by direct and indirect enhancement of UOC and LOC, respectively, and improved SOC sequestration as compared to FR treatment. Finally, the study revealed that SOC quantity and quality were both significantly improved by combined application of mineral fertilizer and organic manure, and this effect was enhanced with the increase of organic manure application. Considering the improvements in soil properties and grain yields, substituting mineral fertilizer with organic manure might be a promising alternative in the North China Plain.

Soil organic carbon (SOC) is highly sensitive to land use change and helps in maintaining soil quality. Changes in soil fertility status, SOC dynamics, and carbon indices were studied in a four-year experiment with nine sets of food-fodder cropping systems (CS) and three resource conservation techniques like rainfed (RC1), life saving irrigation (RC2) and in-situ moisture conservation practices (RC3). Results showed that the CS5 [Tri-Specific Hybrid (TSH) + Desmanthus virgatus+ (Sorghum + Cowpea – Chickpea)] recorded the highest values 12.25 g kg−1, 41.5 mg kg−1, 3.5 g kg−1, 289.5 mg kg−1, 424.8 µg g−1 soil, 54.69% and 39.31% of total carbon (TC), hot water-soluble carbon (HWSC), particulate organic carbon (POC), labile carbon (LC), soil microbial biomass carbon (SMBC), humic acid carbon (HA-C) and fulvic acid carbon (FA-C), respectively. Among resources conservation practices, RC3 improved the SOC (56.16%) and other carbon fractions significantly as compared to RC1. Significant and positive correlations (P < 0.05) were found between carbon pools and available nutrients. The carbon management index (CMI) was also maximum (193) with CS5 and CS9 [TSH + Sesbania sesban+ (Sorghum + Cowpea – Barley)] and RC3 (232). Therefore, promoting cultivation of food-fodder system with in-situ moisture conservation practices is considered as sustainable management option for sequester more carbon, sustainability and soil quality in rainfed semi-arid ecosystem. [ABSTRACT FROM AUTHOR]

The expansion of oil palm (Elaeis guineensis Jacq.) cultivation in degraded areas has increased in the Brazilian Amazon. Cultivation of oil palm in diversified agroforestry systems may be a relatively sustainable alternative to monocultures for crop expansion. Here, we evaluated the effect of oil palm cultivation systems on soil C, an important indicator of the soil quality of production systems. We assessed: (1) whether these systems of oil palm cultivation alter the potassium permanganate oxidizable C content (POx‐C) and the carbon management index (CMI); and (2) how the POx‐C varied among management zones (harvest path, leaf pile, weeded circle, and diversified strip). The soil C indices of the oil palm cultivation systems were also compared with those of secondary forests. POx‐C varied consistently based on the pattern agroforestry > secondary forest = monoculture, ranging from 0.95 ± 0.14 (agroforestry) to 0.66 ± 0.10 g·kg−1 (monoculture). The POx‐C pattern among management zones was pile > diversified strip = weeded circle > harvest path. The CMI was higher in agroforestry than in monoculture. We found that these indices are sensitive to land‐use systems and management practices that affect organic matter input. Organic fertilization and species diversity likely drive the improvement of soil quality in agroforestry systems than in monocultures through C input to the soil directly and indirectly, by creating favorable conditions for the action of root and fauna that in turn positively affect soil C. Therefore, we postulate that soil quality improves through oil palm agroforestry than through oil palm monocultures. [ABSTRACT FROM AUTHOR]

Majority land use changes from the natural forests to commercial agricultural lands, orchards and grazing lands have occurred due to deforestation and land degradation. Soil organic carbon (SOC) is considered as one of the important soil quality parameters for sustainable land management. The present study was formulated to understand the effects of land use changes from forest land to cultivated lands, orchards and grazing lands on carbon pools and carbon stocks in subtropical alfisol ecosystem of Banka district of Eastern India 2015-16. Results showed that soil organic carbon (SOC) in the cultivated land was declined by 47%, 23% and 13%, respectively as compared with the forests, orchards and grazing lands of the soil depth 0-15 cm and 37%, 12% and 12%, respectively in the same order of the soil depth 15-30 cm. The loss of carbon stock in the cultivated soil in the top 30 cm was 14%, and in orchard and grazing land was almost similar while keeping forest soils as a reference. In surface soil, carbon management index (CMI) values for grazing, cultivated and orchards were 93, 83 and 95, respectively, whereas in subsurface soil CMI values for grazing, cultivated and orchards were 95, 92 and 96, respectively as compared to forest land. Overall, SOC content was declined on conversion of forest land to cultivated land in the region. This is alarming situation and requires managing cultivated soil properly otherwise soil productivity will deteriorate and in turn will affect crop productivity in the region.