Search Results (154)

The DNDC-Rice model effectively simulates yield and greenhouse gas emissions within a paddy system, while its performance under upland conditions remains unclear. Using data from a long-term cover crop experiment (fallow [FA] vs. rye [RY]) in a soybean field, this study validated the DNDC-Rice model’s performance in simulating soil dynamics, crop growth, and C-N cycling processes in upland systems through various indicators, including soil temperature, water-filled pore space (WFPS), soybean biomass and yield, CO₂ and N₂O fluxes, and soil organic carbon (SOC). Based on simulated results, the underestimation of cumulative N₂O flux (25.6% in FA and 5.1% in RY) was attributed to both underestimated WFPS and the algorithm’s limitations in simulating N₂O emission pulses. Overestimated soybean growth increased respiration, leading to the overestimation of CO₂ flux. Although the model captured trends in SOC stock, the simulated annual values differed from observations (−9.9% to +10.1%), potentially due to sampling errors. These findings indicate that the DNDC-Rice model requires improvements in its N cycling algorithm and crop growth sub-models to improve predictions for upland systems. This study provides validation evidence for applying DNDC-Rice to upland systems and offers direction for improving model simulation in paddy-upland rotation systems, thereby enhancing its applicability in such contexts. Full article

Understanding how elevation gradients and soil depths influence soil organic carbon stocks (SOCS) and total nitrogen stocks (TNS) is essential for sustainable forest management (SFM) and climate change mitigation. This study investigated the effects of elevation and soil depth on SOCS and TNS in the Mount Kenya East Forest (MKEF). A stratified systematic sampling approach was applied, involving collection of 38 soil samples from two depths (0–20 cm and 20–40 cm) across three elevation zones: Lower Forest (1700–2000 m), Middle Forest (2000–2350 m), and Upper Forest (2350–2650 m). Samples were analysed for bulk density (BD), pH, texture, soil organic carbon (SOC), and total nitrogen (TN), using standard laboratory methods. In topsoil (0–20 cm), SOCS ranged from 109.28 ± 23.41 to 151.27 ± 17.61 Mg C ha⁻¹, while TNS varied from 8.89 ± 1.77 to 12.00 ± 2.46 Mg N ha⁻¹. In subsoil (20–40 cm), SOCS ranged from 72.03 ± 19.90 to 132.23 ± 11.80 Mg C ha⁻¹, with TNS varying between 5.71 ± 1.63 and 10.50 ± 1.90 Mg N ha⁻¹. SOCS and TNS increased significantly with elevation (p < 0.05), exhibiting the following trend: Lower Forest < Middle Forest < Upper Forest. Topsoil consistently stored significantly higher SOCS than subsoil (p < 0.05), emphasizing the critical role of surface soils in carbon sequestration. Regression analysis revealed a significant positive relationship between SOCS and TNS (R² = 0.84, p < 0.001). Both SOCS and TNS were positively correlated with elevation, SOC, TN, and total annual precipitation (TAP), but negatively correlated with BD and mean annual temperature (MAT). These findings provide baseline data for monitoring SOCS and TNS in the MKEF, offering insights into sustainable forest management strategies to improve soil health and enhance climate change mitigation efforts. Full article

Plantation forests (PFs) play a crucial role in China’s climate change mitigation strategy due to their significant capacity to sequestrate carbon (C). Understanding the long-term trend in PFs’ C uptake capacity and the key drivers influencing it is crucial for optimizing PF management and planning for climate mitigation. In this study, we quantified the long-term (1981–2019) C sequestration of PFs in Jiangsu Province, where PFs have expanded considerably in recent decades, particularly since 2015. Seasonal and interannual variations in gross primary productivity (GPP), net primary productivity (NPP), and net ecosystem productivity (NEP) were assessed using the boreal ecosystem productivity simulator (BEPS), a process-based terrestrial biogeochemical model. The model integrates multiple sources of remote-sensing datasets, such as leaf area index and land cover data, to simulate the critical biogeochemical processes governing land surface dynamics, enabling the quantification of vegetation and soil C stocks and nutrient cycling patterns. The results indicated a significant increasing trend in GPP, NPP, and NEP over the past four decades, suggesting enhanced C sequestration by PFs across the study region. The interannual variability in these indicators was associated with that of nitrogen (N) deposition in recent years, implying that nutrient availability could be a limiting factor for plantation productivity. Seasonal GPP and NPP exhibited peak values in spring (April to May) or late summer (August to September), with increases in growing season productivity in recent years. In contrast, NEP peaked in spring (April to May) but declined to negative values in early summer (July to August), indicating a seasonal C source–sink transition. All three indicators showed a general negative correlation with late-growing-season temperature (August to September), suggesting that summer droughts probably highly constrained the C sequestration of the existing PFs. These findings provide insights for the strategic implementation and management of PFs, particularly in regions with a warm temperate climate undergoing afforestation expansion. Full article

Understanding the effects of agricultural practices on soil nutrient dynamics is critical for optimizing land management in arid regions. This study analyzed spatial patterns, driving factors, and surface stocks (0–20 cm) of soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), and their stoichiometric ratios (C:N, C:P, and N:P) across six cropping systems (paddy fields, cotton fields, wheat–maize, orchards, wasteland, and others) in the Aksu region, Northwest China, using 1131 soil samples combined with geostatistical and field survey approaches. Results revealed moderate to low levels of SOC, TN, and TP, and stoichiometric ratios, with moderate spatial autocorrelation for SOC, TN, TP, and C:N but weak dependence for C:P and N:P. Cropping systems significantly influenced soil nutrient distribution: intensive systems (paddy fields and orchards) exhibited the highest SOC (22.31 ± 10.37 t hm⁻²), TN (2.20 ± 1.07 t hm⁻²), and TP stocks (peaking at 2.58 t hm⁻² in orchards), whereas extensive systems (cotton fields and wasteland) showed severe nutrient depletion. Soil pH and elevation were key drivers of SOC and TN variability across all systems. The C:N ratio ranked highest in “other systems” (e.g., diversified rotations), while wheat–maize fields displayed elevated C:P and N:P ratios, likely linked to imbalanced fertilization. These findings highlight that sustainable intensification (e.g., paddy and orchard management) enhances soil carbon and nutrient retention, whereas low-input practices exacerbate degradation in arid landscapes. The study provides actionable insights for tailoring land-use strategies to improve soil health and support ecosystem resilience in water-limited agroecosystems. Full article

The construction of sports spaces such as ski resorts leads to deforestation, soil degradation and carbon (C) loss. However, the impact of ski pistes on soil C and nutrients remains unclear. The impact of an 18-year-old ski piste operation on the stock and stoichiometry of soil C, nitrogen (N), phosphorus (P), bulk density, and water content across a 0–100 cm profile in a forest area in Northeast China was quantitatively assessed using the equivalent soil mass method and fixed depth method. The fixed depth method overestimated soil C, N and P stocks of the SP by 5% to 8% of 0–100 cm stocks of soil C and nutrients relative to the equivalent soil mass method used as a reference. The equivalent soil mass method demonstrated that the ski piste soil C, N, and P stocks were significantly reduced by 27.4%, 21.3%, and 27.5%, respectively, in comparison to the undisturbed forest. Surface layers (0–10 cm) exhibited the highest C and N losses, while deep soil (>50 cm) showed significant C, N and P depletion. The ski piste significantly reduced surface C:N (15.8%) and C:P (38.0%) ratios, indicating decoupled nutrient constraints on C loss. Soil compaction increased bulk density in surface layers (0–10 cm) but reduced it in deeper strata, correlating with altered C physical interdependencies. The findings highlight the vertical stratification of disturbance effects, emphasizing the critical role of stoichiometric controls and methodological considerations in assessing anthropogenic impacts on soil ecosystems. These insights are vital for the sustainable management of ski resorts to mitigate soil degradation. Full article

Faced with the dual challenge of increasing agricultural production (both intensified and diversified) and improving soil health, this study investigated the capacity of legume-based integrated farming systems to restore soil health in the Brazilian Cerrado. For that, we evaluated two experiments in the Minas Gerais State comparing the following land use systems: native vegetation (NV), conventional tillage with Zea mays (CT-8), two pasture systems with Urochloa decumbens (PAST-13) and Urochloa brizantha (PAST-1), and three integrated production systems arranged with Cratylia argentea + Zea mays (IPS-8A), Gliricidia sepium + Zea mays (IPS-8B) and Cratylia argentea + Urochloa brizantha (IPS-1). To assess seasonal variations in microbial attributes (microbial carbon [Cmic], microbial quotient (qMIC), and enzymatic activity, we collected soil samples during the rainy season (December 2021) and the dry season (July 2022). Soil carbon (C) and nitrogen (N) stocks were also evaluated. The soil C and N stocks in pasture systems were similar to VN, with values of 120 and 8.2 Mg ha⁻¹ in PAST-1 at 0–30 cm. Additionally, integrated systems with legume crops promoted an increase in soil C stocks up to 24% (IPS-8B) when compared to monoculture cultivated under conventional tillage (CT-8). We also found that the legume-based integrated farming systems increased Cmic and β-glucosidase activity at the surface layers. Our findings demonstrate that integrated systems utilizing Cratylia argentea and Gliricidia sepium offer a promising approach to soil health restoration and a potential replacement for annual crop and pasture monocultures in the Brazilian Cerrado. Full article

Vegetable production primarily relies on the conventional tillage system (CTS), which leads to soil degradation through erosion and reduced soil health. The use of no-tillage vegetable systems (NTVS) aims to mitigate these issues; however, information about the impact of this management system on soil health and greenhouse gas (GHG) emissions remains limited. Thus, the objective of this study was to conduct an on-farm evaluation of the effects of no-tillage and cover crop use on soil C and N contents and stocks, soil bulk density (SD), mean geometric diameter (MGD) of aggregates, soil temperature, volumetric soil moisture (VM), plant yield, and GHG emissions in cauliflower production under NTVS compared to CTS in a subtropical ecosystem in southeastern Brazil. Chemical and physical properties were assessed at depths of 0–5, 5–10, and 10–30 cm. GHG emissions, particularly nitrous oxide (N₂O), carbon dioxide (CO₂), and methane (CH₄) were measured using closed static chambers and gas chromatography. NTVS with cover crop mixes had higher yield than CTS without cover crops (25.1 and 18.4 Mg ha⁻¹, respectively). NTVS exhibited increased MGD and VM and reduced SD. Soil temperature in the 0–5 cm layer was lower in NTVS than in CTS. Soil C and N stocks were higher in NTVS, but high N₂O emissions offset this advantage compared to CTS. Overall, NTVS emitted more CO₂ and N₂O than CTS, while both systems showed soil CH₄ uptake. NTVS maintained sufficient carbon equivalent reserves (0–30 cm) to offset GHG emissions, making it a viable alternative for plant yield and soil quality; however, its environmental impact on GHG emissions requires further attention. Full article

Agroforestry contributes to slowing deforestation, favoring ecosystem regeneration and improving land use sustainability. This study evaluated the impact of silvopastoral systems on soil recovery and their capacity to sequester and stabilize carbon (C) and nitrogen (N) in degraded soils of a native Nothofagus obliqua forest in Ranchillo Alto (37°04′52″ S, 71°39′14″ W), Ñuble Region, Chile. Three open (Op), semi-open (SOp), and semi-closed (SC) silvopastoral systems were analyzed and compared with a control (Ctr) without silvopastoral management across four soil depths (0–10, 10–20, 20–30, 30–60 cm). Physical, chemical, and biological analyses were performed, along with soil physical organic matter (SOM) fractionation. The highest C levels were found in the 0–10 cm depth (13.9, 11.8, 11.5, and 8.5% for Op > SC > SOp and Ctr, respectively). Despite its higher degradation, Op presented the highest levels of C, N, and non-oxidizable C (Cnox), possibly due to pyrogenic carbon from old potato burns. Furthermore, the same trend was observed for mineral associated organic matter (MAOM) fraction and C stocks in all silvopastoral systems compared to the control. These results underline the potential of silvopastoral practices to improve soil quality and increase long-term carbon sequestration, contributing to sustainable soil restoration strategies. Full article

Grassland soil carbon stocks contain substantial amounts of organic carbon and play a crucial role in the global carbon cycle. Grazing is one of the most primary land use types in grasslands. However, few studies have focused on the impact of three grazing behaviors (mowing (M), trampling (T), and dung and urine addition (D)) on the soil organic carbon (SOC) of mountain meadows. In this experiment, we simulated three grazing behaviors to explore the impacts of grazing behaviors on plant characteristics with plant growth, soil physicochemical properties, soil aggregate, and analyzed the main factors influencing the changes in SOC. After six years of treatment, the experimental results showed that M significantly decreased plant height, density, and aboveground biomass and significantly decreased soil organic carbon (SOC) (no M vs. M, −3.64%). T significantly increased soil bulk density, the proportion of macroaggregates, the organic carbon of microaggregates, and silt and clay aggregates and significantly increasing SOC (no T vs. T, +3.17%). D significantly increased plant density, soil total nitrogen and the organic carbon of macroaggregates, significantly increasing SOC (no D vs. D, +9.74%). Correlation and principal component analyses indicated that SOC was significantly negatively correlated with soil bulk density and plant coverage and significantly positively correlated with soil total nitrogen, soil C/N, microaggregate proportion, and the organic carbon of macroaggregates. Redundancy analysis indicated that the proportion of microaggregates and the organic carbon of macroaggregates were the main factors influencing SOC. The following conclusions were drawn: SOC responds differently to three types of grazing behaviors, D primarily increases the organic carbon in macroaggregates, while T mainly enhances the organic carbon in microaggregates and silt and clay aggregates, thereby affecting the SOC in mountain meadows. Full article

Biochar (BCH) amendments represent a valuable strategy for increasing forest carbon stock, but their effects on soil respiration of beech forests under climate change are largely unknown. We conducted a short-term mesocosm experiment investigating the impact of BCH applications (0%, 10%, 20%, and 50%, v/v) on respiration of a European beech forest soil in N-Italy. The experiment, carried out in Parma, was conducted under both ambient and modified climatic conditions, involving higher soil temperatures (c. +1 K) and reduced precipitation (−50%). The experiment was performed during autumn 2022 and repeated in spring 2023, periods representing late and early summer, respectively. Soil respiration significantly increased with BCH applications when compared to controls, irrespective of the percentage applied. The highest values were recorded in the 20% amendment, while values were significantly lower in BCH 50%, similar to those recorded in BCH 10%. Although soil respiration and soil temperature were positively correlated, no effect of simulated warming was observed. No effects of precipitation reduction were also found, despite respiration being significantly influenced by soil moisture. These results provide an initial insight into the potentially negligible impact of BCH applications on soil respiration in European beech forests under both current and future climate scenarios. Full article

European grasslands are vital carbon (C) sinks, contributing to climate change mitigation. Grazing intensity significantly influences soil C and nitrogen (N) cycles through effects on soil conditions and microbial communities. While heavy grazing is linked to soil C loss and altered N processes, existing studies show conflicting outcomes. This study examines the impact of cattle grazing on soil C and N cycles in a historical alpine pasture in the eastern Italian Alps (1868 m a.s.l.). The following three grazing intensities were analyzed: heavy (8.19 LU ha⁻¹), moderate (0.59 LU ha⁻¹), and light (0.06 LU ha⁻¹). Soil was sampled from two depth layers (0–5 cm, 5–10 cm) and analyzed for bulk density, C and N content, C/N ratio, exchangeable N, δ¹⁵N, and microbial genes targeting general abundance (16S), N fixation (nifH), nitrification (amoA), and denitrification (nirK, nosZ) using real-time PCR. The results revealed decreased C and N concentrations with increasing grazing intensity, exclusively in the 0–5 cm soil layer. Higher δ¹⁵N and enhanced nitrification and denitrification suggest a more open N cycle under heavy grazing. These findings highlight the potential of microbial gene markers and δ¹⁵N isotopic ratios to monitor N cycle dynamics in alpine pastures, informing sustainable grazing management. Full article

Intercropped systems are regarded as a promising strategy for generating multiple benefits to the ecosystems in the rubber-plantation zone. However, knowledge about the impacts of intercropped systems with rubber on carbon and nitrogen storage in soils and their affecting factors is limited. In this study, three rubber-based intercropped systems, including rubber intercropped with Theobroma cacao, Coffea liberica, and Camellia sinensis, as well as rubber monoculture, were selected in Xishuangbanna, a typical rubber plantation zone in China. We collected soil samples from 0–10, 10–20, and 20–40 cm depths to analyze soil bulk density (BD), soil organic carbon (SOC), soil total nitrogen (TN), pH, the ratio of carbon and nitrogen (C/N), dissolved organic carbon (DOC), and dissolved organic nitrogen (DON). The results showed that rubber trees intercropped with C. liberica significantly increased the SOC and TN stocks of the 0–40 cm soil layer by 19.9% and 13.6%, respectively, compared to rubber monoculture. Soil properties usually had strong relationships with SOC and TN stocks. Our study demonstrated that rubber with the C. liberica intercropped system had greater potential for C and N sequestration in this tropical region. Full article

Wood from reforestation gains market value due to its sustainable and legal origin. Planted forests in Brazil play a crucial role in economic, social and environmental aspects, with Eucalyptus and Pinus dominating the timber sector. However, non-majority species, such as those of the Khaya genus, have attracted great commercial interest due to the quality of their wood, being seen as an alternative to Brazilian mahogany. This study aimed to evaluate the biomass production of Khaya spp. stands and the nutrient uptake impacts in different harvesting scenarios. The research area is in Reserva Natural Vale (RNV) in Sooretama, Espírito Santo state, Brazil. The study was conducted 9.5 years after the planting of the Khaya spp. monoculture at a spacing of five m × five m, and the base fertilization consisted of 150 g of yoorin thermophosphate and 15 g of FTE BR 12 per seedling. The seedlings were of seminal origin, coming from different regions of Brazil and corresponding to three species: Kkaya grandifoliola C.DC (Belém-PA), Khaya ivorensis A. Chev. (Linhares-ES) and Khaya senegalensis A. Juss. (Poranguatu-GO). K. senegalensis exhibited the highest percentage of bark, while K. ivorensis was found to have the highest percentage of leaves. The biomass of the stems and branches did not vary by species. The relative biomass proportions had the following order: branches > stems > bark > leaves. The stocks of Ca and Mg were higher for K. grandifoliola, exceeding those for K. senegalensis (22.1%) for Ca and for K. ivorensis (42.3%) for Mg. The lowest nutrient uptake occurred in the scenario in which only the stem was removed, with averages of 44.17, 10.43, 21.93, 52.59 and 9.97 kg ha⁻¹ for N, P, K, Ca and Mg, respectively. Compared to total biomass harvesting, this represents a reduction in export levels by 91.34% for N, 79.31% for P, 94.66% for K, 94.29% for Ca and 93.28% for Mg. The nutrient uptake assessment demonstrated that more conservative harvest scenarios resulted in lower nutrient losses, indicating the importance of forest management practices that prioritize soil and nutrient conservation. In summary, the findings of this study provide a solid basis for the sustainable management of Khaya spp., highlighting implications for productivity and nutrient dynamics on a small or medium scale. Full article

This study aimed to analyze the carbon (C) stock and stabilization of soil organic matter in particulate- and mineral-associated fractions across different land use systems after 32 years of experimentation in the Brazilian Cerrado. The experiment was established in 1991 and was performed in Planaltina-DF. The treatments evaluated included continuous pasture with monoculture grasses; integrated crop–livestock systems under no tillage; continuous cropping under no tillage; minimum tillage; and the preservation of the native Cerrado biome in its original condition. Soil sampling was performed to a depth of 30 cm. Carbon and nitrogen (N) stocks were quantified for the years 2001, 2009, 2013, and 2023, with soil organic matter fractionation performed on samples from 2023. Land use change resulted in significant losses of soil C and N in areas managed with conventional soil preparation practices. Systems that promote plant diversity, such as integrated crop–livestock systems, enhanced soil C and N stocks (72.8 and 5.5 Mg ha⁻¹, respectively) and increased both particulate organic matter and mineral-associated fractions, most of which were in more stabilized forms. Integrated crop–livestock systems are management practices that offer an effective alternative to present methods in terms of combating climate change and supporting ecosystem sustainability. Full article

The conversion of caatinga vegetation areas into pastures in the Brazilian semiarid region has depleted soil fertility due to degradation. The natural regeneration of the caatinga has been the alternative adopted to restore soil fertility. However, the real effectiveness of this practice in recovering organic carbon (SOC) and nutrient stocks is unknown. This work evaluated the effect of natural regeneration of the caatinga vegetation on the restoration of levels and stocks of SOC, N, and P as a strategy to maintain the sustainability of the environment. We collected soil samples every 5 cm, up to 20 cm deep, in areas of degraded pasture, caatinga in regeneration (10 years), and regenerated caatinga (35 years) to evaluate the levels and stocks of SOC, N, and P. The depth significantly affects the levels and stocks of SOC, N, and P. Stocks and levels of SOC, N, and P were higher in regenerated caatinga > regenerating caatinga > degraded pasture. The regenerated caatinga increased SOC, N, and P stocks by 115%, 110%, and 117%, respectively, compared to the degraded pasture. Although 35 years of regeneration of the caatinga has improved soil fertility, the levels and stocks of SOC, N, and P remain low. Full article