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Background: Land use and land cover changes have a significant impact on the dynamics of soil organic matter (SOM) and its fractions, as well as on overall soil health. This study conducted in Bharatpur Catchment, Chitwan District, Nepal, aimed to assess and quantify variations in total soil organic matter (TSOMC), labile organic matter fraction (CL), stable organic matter fraction (CS), stability ratio (SR), and carbon management index (CMI) across seven land use types: pastureland, forestland, fruit orchards, small-scale conventional agricultural land, large-scale conventional agricultural land, large-scale alternative fallow and conventional agricultural land, and organic farming agricultural land. The study also explored the potential use of the Carbon Management Index (CMI) and stability ratio (SR) as indicators of soil degradation or improvement in response to land use changes. Results: The findings revealed significant differences in mean values of TSOMC, CL, and CS among the different land use types. Forestland and organic farming exhibited significantly higher TSOMC (3.24%, 3.12%) compared to fruit orchard lands (2.62%), small scale conventional farming (2.22%), alternative fallow and conventional farming (2.06%), large scale conventional farming (1.84%) and pastureland (1.20%). Organic farming and Forestland also had significantly higher CL (1.85%, 1.84%) and CS (1.27%, 1.39%) compared to all other land use types. Forest and organic farming lands showed higher CMI values, while pastures and forests exhibited higher SR values compared to the rest of the land use types. Conclusions: This study highlights the influence of various land use types on soil organic matter pools and demonstrates the potential of CMI and SR as indicators for assessing soil degradation or improvement in response to land use and land cover changes. [ABSTRACT FROM AUTHOR]

Soil carbon management practices are those that add and maintain organic carbon in the soil. These agricultural practices can potentially both contribute to climate change mitigation and increase the soil's resilience to physical and biological stresses. The paper draws on research findings from five regions across Europe to identify regionally-specific barriers to and opportunities for the adoption of soil carbon management practices. Data were derived from 50 interviews with policy-makers and advisers and 5 stakeholder workshops in Denmark, Italy, Hungary, Poland and Spain. Several barriers to the uptake of soil carbon management practices were common across all regions, however, regional variations were also identified highlighting the importance of understanding the context into which these practices are introduced. Key barriers related to existing biophysical conditions, lack of financial support, farmer knowledge and experience, and the quality of the advisory service. Opportunities included providing economic incentives, harmonizing regulation, supporting long term thinking and planning for resilience and providing good quality advice. We conclude that in addition to persuasive mechanisms for encouraging the adoption of these practices, what is required is a more process-oriented approach that focuses on a series of experiential changes and fosters farmer learning through interactive models of communicative intervention. [ABSTRACT FROM AUTHOR]

Cropping systems and fertilization have important effects on soil organic carbon (OC) and nitrogen (N) turnover and availability; however, little information exists about the interaction of cropping system and fertilization. Herein, we analyzed the dynamics of soil OC and N in a 31-year experiment in a highland agroecosystem to understand how the effects of fertilization vary with cropping systems. The experiment included different cropping systems, and each system included various fertilization treatments. The cropping systems were continuous alfalfa (Medicago sativa L.), continuous winter wheat (Triticum aestivum L.), and grain-legume rotation of winter wheat + millet (Panicum miliaceum L.) - pea (Pisum sativum L.) - winter wheat. The fertilization treatments were the control (CK), phosphorous (P), P and nitrogen (NP) and NP and manure (NPM). A bare fallow treatment that did not receive any crop and fertilizer was designed to compare the effects of the cropping systems. The soil samples were collected at different times of the experiment. The contents of OC, N, and labile OC were measured, and the carbon management index was calculated. When averaged across the experimental periods, soil OC, N, labile OC and carbon management index were significantly higher in the pure legume (i.e., continuous alfalfa) system than in the bare fallow and nonlegume system (i.e., continuous winter wheat) due to the higher C and N inputs from root biomass. The NP and NPM significantly increased these soil variables, and the effects of NPM were greater than those of NP due to the higher supplying of C and N in NPM treatment than NP treatment. However, the effects of NP or NPM on soil OC and N contents were similar among the cropping systems. The effects of P were greater in the continuous alfalfa system but smaller in the continuous winter wheat system in comparison with those in the grain-legume rotation system. Therefore, at the conditions of our study, legume-included cropping systems with large root biomass and manure combined with chemical fertilizers have the potential to increase OC and N and their availability in highland soils, which could be important strategies for improving soil fertility and quality and sequestrating C in soils. Moreover, P fertilizer was recommended for the legume-included cropping systems. • We studied the effects of fertilization on soil OC and N in three cropping systems. • Continuous legume, continuous winter wheat and a grain-legume rotation were tested. • Legume increase soil OC and N and their availability. • Effects of NP or NP combined with manure were similar among cropping systems. • Effects of chemical P fertilizer on soil OC and N varied with cropping systems. [ABSTRACT FROM AUTHOR]

Estimating regional carbon (C) stocks and understanding their dynamics is crucial, both from the perspective of sustainable landscape management and global change feedback. This study combines remote sensing techniques and a coupled GIS-CENTURY model to estimate regional biomass C stocks and SOC dynamics for Guiera senegalensis shrub communities in Senegal''s Peanut Basin. A statistical model relating field-measured shrub aboveground biomass C at training plots to satellite image-derived shrub abundances was developed and used to estimate regional biomass C across a major part of the Basin. Regional SOC dynamics were modeled by coupling the CENTURY model and GIS databases. Significant correlation (r =0.73; p =0.05) was observed between aboveground biomass C and satellite image-derived shrub abundance at the training plots. Aboveground biomass C stocks ranged from 0.01 to 0.45Mgha−1 with an approximate total of 247,000MgC for the 3060km2 study area. CENTURY model predictions indicate that C sequestration in these systems is contingent on long-term effectiveness of non-thermal management of shrub residue and that the actual rates depend strongly on soil type and scenarios of future land management. Compared with the traditional “pruning-burned” management practice, returning prunings for 50 years would increase soil C sequestration by 200–350% without fertilization, and increase soil C sequestration by 270–483% under a low (35kgha−1 Nyr−1; 20kgha−1 Pyr−1) fertilization regime, depending on soil type and climate conditions. These results indicate that altered land management could contribute to transforming these degraded semiarid agroecosystems from a source to a sink for atmospheric CO2. [Copyright &y& Elsevier]