The soils in urban greenery considerably contribute to providing ecosystem services. However, appropriate tools to assess and manage urban soil quality under consideration of ecosystem services and ...soil functions are unavailable. In this study, we aimed to 1) provide detailed instructions for assessing a novel urban soil quality index (uSQI) and 2) propose the application of uSQI in urban soil quality management. The uSQI is the average of the scores for six soil functions. Each soil function was estimated by several measurable indicators that have high correlation with soil functions. The measurable soil indicators are bulk density, saturated hydraulic conductivity, litter-layer depth, mineral-associated organic matter, clay + silt content, inorganic nitrogen concentration, fluorescein diacetate hydrolytic activity, cation exchange capacity, concentrations of potentially toxic elements, and pH. The uSQI effectively identified the soils with low quality due to disturbances. The radar chart of six soil functions comprising uSQI could suggest the direction of management for urban stakeholders.•The uSQI represents soil functions necessary for urban greenery to provide ecosystem services.•The uSQI successfully identified the soils with low quality due to disturbances.
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Simulation of conservation tillage effect on soil organic carbon (SOC) stock on the national scale is essential for Tier 3 level greenhouse gas inventory in the agricultural sector. However, the ...conservation tillage effects varied depending on different soil conditions, potentially leading to inaccurate national assessments. This study aimed to propose a framework for estimating the national scale impact of conservation tillage on SOC. As even in the most commonly used SOC dynamic model, the Rothamsted Carbon Model (RothC), does not reflect the conservation tillage effect in an explicit way, we modified it by developing the tillage rate modifiers (TRMs). First, we investigated the conditions for the inconsistent conservation tillage effects using the decision tree analysis based on 210 field experiment data from the mid-latitude region. The results highlighted that soil sand content and the existing SOC stock were the main factors driving the inconsistencies. After we categorized into four distinctive conditions, the TRMs for each condition were parameterized using a genetic algorithm. The average TRMs were 0.88 in the soils with sand content >37.6 % and 1.58 in the soils with sand content ≤37.6 %, indicating that conservation tillage is more effective in coarse-textured soil, and there is a risk of decreasing SOC stock in the latter condition. Using the modified RothC model, a three-step national-scale simulation framework was suggested: compiling country-specific data, establishing baseline and conservation tillage scenarios, and modeling conservation tillage effects with uncertainty analysis. Our approach also defined the maximum conservation tillage area, factoring in local cropping systems and soil conditions. Our refined RothC model with TRMs provides a nuanced understanding of conservation tillage effects, emphasizing the role of soil characteristics. The proposed national-scale simulation framework offers a reliable tool for evaluating conservation tillage impact on SOC, ensuring more accurate greenhouse gas inventories in agriculture.
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•The effect of conservation tillage on SOC stock showed significant inconsistency.•Soil sand content and initial SOC stock drive conservation tillage inconsistencies.•Tillage rate modifiers for RothC model were developed separately for different soil conditions.•Enhanced RothC model reflects variances in tillage effects across middle-latitude region.•A national-scale framework to evaluate the potential of conservation tillage were suggested.
While there are extensive studies reporting a reduction in N2O emission by biochar addition, there are some cases that showed an increase in N2O emission. To identify the primary conditions that lead ...to an increase in N2O emissions, we conducted a decision tree analysis of 148 observations from 25 published papers. It was verified that biochar made with rice husk, rice straw, nut-shell, pits, and stones had a higher chance of increasing N2O emissions than biochar made with wood, herbaceous, and biosolid. Moreover, it was also demonstrated that the probability of increasing N2O emission by former group biochar was higher in the low pH soils. The latter group of biochar showed the lowest probability of increasing N2O emission in soil with low soil organic carbon (SOC) content. The decision tree analysis results led us to conduct an incubation experiment to understand the underlying mechanisms under which conditions biochar increases or decreases soil N2O emissions. The soils amended with urea and 4% (w/w) biochars (cocopeat: CPB, rice husk biochar: RHB, and wood pellets: WPB) were incubated for 15 days on aerobic condition. As a result, N2O emissions increased in the soils amended with CPB and RHB, which was consistent with decision tree analysis. The high labile matter content of these biochar could stimulate both heterotrophic denitrification and nitrification-mediated processes. In the soil with the high labile matter biochar which increased soil pH throughout the experimental period (CPB treatment), NO2− was accumulated and gene abundance of nitrite-oxidizing bacteria were reduced, which might be caused by NH3 toxicity. Our results can be utilized as a practical guideline to maximize biochar's climate change mitigation potential.
•We identified conditions that biochar increase N2O emission in non-flooded soil.•Biochar with a low C/N ratio has a higher chance of increasing soil N2O emissions.•The probability of increasing N2O emission was higher where biochar raises soil pH.•Labile matter of biochar stimulated both the nitrification and denitrification processes.
•Biochar alleviated drought conditions by improving soil physical structure.•Enhanced macro-aggregation by biochar might increase the formation of meso-pores.•Meso-pores could retain more soil water ...for plant uptake.•Biochar is one of promising strategies for mitigating drought in urban roadside greenery.
Soil structure degradation is a major obstacle to vegetation growth in urban roadside greenery, particularly under drought conditions. Biochar application can improve soil structure and water retention; however, the mechanisms linking changes in soil aggregation with those in pore size distribution, and how they interactively influence plant growth remain unclear. In this study, we investigated the role of biochar in improving soil structure and water retention under drought stress in urban roadside greenery. In a field study, plots (2 m × 2 m) were established on roadside greenery in Suwon, Korea, in which 2.5% wt bochar was mixed with surface soil (<10 cm depth) (BCfield). During the eight-month experiment, drought conditions prolonged, and soil water content was continuously higher in BCfield than in CONfield. For a more mechanistic understanding, a 100-day greenhouse experiment was conducted on Rudbeckia hirta planted in sandy soil, either mixed with 4% wt biochar (BCgreenhouse) or without biochar (CONgreenhouse). Drought conditions were simulated by maintaining soil water content below 40% of the water-holding capacity. In the biochar-added soil, macro-aggregates (250–1000 μm) increased significantly after 60 days, probably due to biochar particles themselves acting as the same-sized aggregates. In addition, biochar can act as a binding agent for forming macro-aggregates, thereby preventing their disintegration into smaller-sized aggregates. Enhanced macro-aggregation in biochar-added soil, therefore, is a potential mechanism for the increased formation of meso-pores. These pores could retain more soil water for plant uptake, eventually increasing plant biomass and water use efficiency in the BCgreenhouse, by 39%, when compared with that in the CONgreenhouse under drought conditions. Our results indicate that biochar application is a potential management strategy for improving soil physical structure in urban roadside greenery, which would, in turn increase plant resistance and resilience to drought stress.
The soils in urban greenery provide essential ecosystem services. However, only a few studies have assessed urban soil quality based on a comprehensive view of ecosystem services and soil ...multi-functionality. In this study, we suggest an urban soil quality index (uSQI) to evaluate soil status in various spatial types of urban greenery. Our objectives are 1) to develop an uSQI incorporating a range of urban soil ecosystem services in metropolitan environments and 2) to test the efficacy of the developed uSQI by applying it to nine different sites. To fully consider ecosystem services provided by the urban soil, a DPSC (drivers and pressures, state, and changes) framework was constructed. Drivers and pressures are influencing factors that continuously alter the state of the urban greenery, eventually leading to changes in ecosystem services and soil functions. The six soil functions considered were physical stability and support, water storage and infiltration, habitat provision, organic matter stabilization, nutrient supply and retention, and pollutant immobilization and decomposition. These functions were measured using ten soil indicators which can be quantified: bulk density, saturated hydraulic conductivity, litter-layer depth, mineral-associated organic matter, clay+silt content, fluorescein diacetate hydrolytic activity, cation exchange capacity, inorganic nitrogen concentration, pH, and concentrations of potentially toxic elements. The uSQI was calculated as the arithmetic mean of the scores of the six soil functions, obtained through the fuzzy logic functions. The uSQI successfully identified the low soil quality sites among nine urban greeneries with different spatial types (point, line, and polygon). In addition, we could examine the degraded soil function of each site and suggest a management guideline using our uSQI. Our novel index can help urban stakeholders evaluate and monitor the soil quality of urban greenery.
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•Soils of urban greenery provide various ecosystem services but are often impaired.•A novel urban soil quality index (uSQI) is presented for soil quality assessment.•uSQI comprehensively considered ecosystem services and functions of urban soil.•uSQI successfully identified the low soil quality sites and degraded functions.
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•Meta-analysis reveals Arctic soil labile nitrogen (N) responses to climate change.•Warming shows no overall effect, while snow addition alters soil labile N pools.•Decision tree ...analysis identifies key determinants of soil labile N changes.•Climate, soil, vegetation, and experimental factors shape soil labile N responses.•Provide insights into the responses of Arctic N dynamics to climate change.
The Arctic terrestrial ecosystems are undergoing rapid climate change, causing shifts in the dynamics of soil nitrogen (N), a pivotal but relatively underexplored component. To understand the impacts of climate change on soil labile N pools, we performed meta- and decision-tree analyses of 391 observations from 38 peer-reviewed publications across the Arctic, focusing on experimental warming and snow addition. Soil dissolved organic nitrogen (DON), ammonium (NH4+), and nitrate (NO3-) pools under experimental warming exhibited overall standard mean differences (SMDs) ranging from −0.08 to 0.02, with no significance (P > 0.05); however, specific conditions led to significant changes. The key determinants of soil labile N responses to warming were experimental duration and mean annual summer temperature for DON; annual precipitation, soil moisture, and sampling timing for NH4+; and soil layer for NO3-. Snow addition significantly increased all labile N pools (overall SMD = 0.23–0.36; P < 0.05), influenced by factors such as sampling timing and vegetation type for DON; experimental duration and soil moisture for NH4+; and soil pH for NO3-. By consolidating and reprocessing datasets, we not only showed the overall responses of soil labile N pools to climate manipulation experiments in Arctic tundra ecosystems but also identified key determinants for changes in soil N pools among environmental and experimental variables. Our findings demonstrate that warming and snow-cover changes significantly affect soil labile N pools, highlighting how the unique environmental characteristics of different sites influence terrestrial N cycling and underscoring the complexity of Arctic N dynamics under climate change.
Soil carbon storage is considered an important climate change mitigation strategy as it represents a major carbon storage reservoir in the global carbon cycle. Ministry for Food, Agriculture, ...Forestry and Fisheries (MIFAFF) set up the Agricultural Environment Conservation Program and agricultural practices to promote soil carbon storage are included as important activities. However, there is no established methodology to quantify the performance of agricultural practices that can enhance soil carbon storage. In this study, a methodology and tool were developed to quantify changes in soil carbon storage related to conservation actions. First, cropland was divided into rice paddies, agricultural fields, and perennial/tree crops, and agricultural activities were systematized considering domestic agricultural circumstances. No-till farming, cultivation of green manure, crop residue return, compost application, and biochar input were considered. Next, default factors of IPCC (Intergovernmental Panel on Climate Change) guideline and domestic research papers were reviewed to find the relevant effects of different activities on soil carbon storage. Finally, a spreadsheet for calculating changes in soil organic carbon stock was built using Microsoft Excel. The developed method was applied to Sangju-si and Boryeong-si, which joined the Agricultural Environment Conservation program, and the total increase in soil carbon storage in 20 years was calculated as 255.0 ton C and 356.8 ton C, respectively. The methodology and soil carbon stock calculator established in this study will be able to more accurately reflect the domestic situation if country-specific emission factors are incorporated in the future. KCI Citation Count: 0
