Carbon Footprint Management by Agricultural Practices.

Global attention to climate change issues, especially air temperature changes, has drastically increased over the last half-century. Along with population growth, greater surface temperature, and higher greenhouse gas (GHG) emissions, there are growing concerns for ecosystem sustainability and other human existence on earth. The contribution of agriculture to GHG emissions indicates a level of 18% of total GHGs, mainly from carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). Thus, minimizing the effects of climate change by reducing GHG emissions is crucial and can be accomplished by truly understanding the carbon footprint (CF) phenomenon. Therefore, the purposes of this study were to improve understanding of CF alteration due to agricultural management and fertility practices. CF is a popular concept in agro-environmental sciences due to its role in the environmental impact assessments related to alternative solutions and global climate change. Soil moisture content, soil temperature, porosity, and water-filled pore space are some of the soil properties directly related to GHG emissions. These properties raise the role of soil structure and soil health in the CF approach. These properties and GHG emissions are also affected by different land-use changes, soil types, and agricultural management practices. Soil management practices globally have the potential to alter atmospheric GHG emissions. Therefore, the relations between photosynthesis and GHG emissions as impacted by agricultural management practices, especially focusing on soil and related systems, must be considered. We conclude that environmental factors, land use, and agricultural practices should be considered in the management of CF when maximizing crop productivity.

Spatial responses of soil carbon stocks, total nitrogen, and microbial indices to post-wildfire in the Mediterranean red pine forest.

Wildfire is a key ecological event that alters vegetation and soil quality attributes including biochemical attributes at spatial scale. This knowledge can provide insights into the development of better rehabilitation or restoration strategies that depend on the ecological dynamics of vegetation, fungi, and animals. The present study aimed to understand the causes and consequences of spatial variability of soil organic carbon, microbial biomass C concentrations, and soil quality indices as impacted by wildfire in a red pine forest. This study was conducted using kriging and inverse distance neighborhood similarity (IDW) interpolations methods. The carbon stocks were significantly (P = 0.002) higher in burned areas compared to those of unburned areas by 255% whereas microbial biomass carbon and microbial respiration were significantly (P < 0.0001 and P = 0.02) lower in burned areas by 66% and 90%, The Pearson's correlation analysis showed that carbon stocks were positively correlated with pH (0.61), total nitrogen (0.60) and ash quantity (0.41), but negatively correlated with microbial biomass carbon (-0.46) and nitrogen (-0.61), and microbial respiration (-0.48). The IDW interpolation method better-predicted pH, bulk density, and microbial biomass carbon and nitrogen compared to kriging interpolation, whereas the kriging interpolation method was better than IDW interpolation for the other studied soil properties. We concluded that pH, EC, SOC, C/N, MR, MBC/SOC, and MBC/MBN can be reliable indicators to monitor the effect of wildfire on forest soils. The wildfire event increased soil carbon stocks, TN, pH, and qCO2, but decreased MBC and MBN.

Data describing the eco-physiological responses of Elaeagnus angustifolia grown under contrasting regime of water and fertilizer in coal-mined spoils.

To improve our understanding of how coal mining areas can be re-vegetated and ecosystem function restored, we examined the potential effects of five water (W) regimes (40, 50, 60, 70 and 80% of field capacity), five nitrogen (N) (0, 24, 60, 96 and 120 mg kg‒1 soil) and five phosphorus (P) fertilizer doses (0, 36, 90, 144 and 180 mg kg‒1 soil), which control the growth and development of Elaeagnus angustifolia under adverse environmental conditions. To optimize the W-N-P application rate, three factors and five levels of central composite design along with an optimization technique named response surface methodology were utilized. Here we provide data on root-shoot biomass ratio, leaf dry matter content, stomatal conductance, chlorophyll (Chl) a, Chl b, membrane stability index and soluble protein content of E. angustifolia. The data described in this article are available in Mendeley Data, DOI: 10.17632/2vfbrdxyf2.2[1]. These data could be used to evaluate the improvement in growth performance of E. angustifolia subjected to various regimes of W, N and P. This dataset showed that E. angustifolia grew optimally in coal-mine spoils when irrigated at 66% of field capacity and supplemented with 74.0 mg N and 36.0 mg P kg‒1 soil. This could considerably help the success of revegetation in coal-mined degraded arid areas where W is scarce. This article contains data complementary to the main research entitled "Fine-tuning of soil water and nutrient fertilizer levels for the ecological restoration of coal-mined spoils using Elaeagnus angustifolia" in the Journal of Environmental Management (Roy et al., 2020).

Management Strategies to Mitigate N2O Emissions in Agriculture.

The concentration of greenhouse gases (GHGs) in the atmosphere has been increasing since the beginning of the industrial revolution. Nitrous oxide (N2O) is one of the mightiest GHGs, and agriculture is one of the main sources of N2O emissions. In this paper, we reviewed the mechanisms triggering N2O emissions and the role of agricultural practices in their mitigation. The amount of N2O produced from the soil through the combined processes of nitrification and denitrification is profoundly influenced by temperature, moisture, carbon, nitrogen and oxygen contents. These factors can be manipulated to a significant extent through field management practices, influencing N2O emission. The relationships between N2O occurrence and factors regulating it are an important premise for devising mitigation strategies. Here, we evaluated various options in the literature and found that N2O emissions can be effectively reduced by intervening on time and through the method of N supply (30-40%, with peaks up to 80%), tillage and irrigation practices (both in non-univocal way), use of amendments, such as biochar and lime (up to 80%), use of slow-release fertilizers and/or nitrification inhibitors (up to 50%), plant treatment with arbuscular mycorrhizal fungi (up to 75%), appropriate crop rotations and schemes (up to 50%), and integrated nutrient management (in a non-univocal way). In conclusion, acting on N supply (fertilizer type, dose, time, method, etc.) is the most straightforward way to achieve significant N2O reductions without compromising crop yields. However, tuning the rest of crop management (tillage, irrigation, rotation, etc.) to principles of good agricultural practices is also advisable, as it can fetch significant N2O abatement vs. the risk of unexpected rise, which can be incurred by unwary management.

Mitigation of lead (Pb) toxicity in rice cultivated with either ground water or wastewater by application of acidified carbon.

Toxicity induced by a high concentration of lead (Pb) can significantly decrease plant's growth, gas exchange, and yield attributes. It can also causes cancer in humans. The use of organic amendments, especially biochar, can alleviate Pb toxicity in different crops. The application of biochar can decrease the uptake of Pb by plant roots. However, the high pH of thermo-pyrolyzed biochar makes it an unfit amendment for high pH soils. As Pb is an acute toxin and its uptake in rice is a major issue, the current experiment was conducted to explore the efficacy of chemically produced acidified carbon (AC) to mitigate Pb toxicity in rice. Lead was introduced in concentrations of 0, 15, and 30 mg kg-1 soil in combination with 0, 0.5, and 1% AC, underground water (GW) and wastewater (WW) in rice plants. The addition of 1% AC significantly improved the plant height (52 and 7%), spike length (66 and 50%), 1000 grains weight (144 and 71%) compared to 0% AC under GW and WW irrigation, respectively at 30 mg Pb kg-1 soil (30 Pb) toxicity. Similar improvements in the photosynthetic rate, transpiration rate and stomatal conductance also validated the effectiveness of 1% AC over 0% AC. A significant decrease in electrolyte leakage and plant Pb concentration by application of 0.5 and 1% AC validates the effectiveness of these treatments for mitigating 30 Pb toxicity in rice compared to 0% AC under GW or WW irrigation. In conclusion, 1% AC is an effective amendment in alleviating Pb toxicity in rice irrigated with GW or WW at 30 Pb.

Seasonal Variations in Litter Layers' Characteristics Control Microbial Respiration and Microbial Carbon Utilization Under Mature Pine, Cedar, and Beech Forest Stands in the Eastern Mediterranean Karstic Ecosystems.

The forest floor is hotspot of several functions integral to the stability of forest ecosystems. However, seasonal variations in litter decomposition rate contribute to biochemical and structural heterogeneity in the forest floor carbon (C) and nutrient cycling. We investigated the influence of seasonal variations in litter layers' micro-climate (temperature and moisture content) and chemical characteristics such as pH, electrical conductivity (EC), total organic C (TOC), total nitrogen (TN), and C/N ratio on microbial respiration, biomass, and C use efficiency under mature (> 80 years stage age) pine, beech, and cedar forests in eastern Mediterranean Karstic ecosystems. In contrast to significantly higher microbial respiration in fall, winter, and spring under pine, beech, and cedar forests, the significantly lowest microbial biomass C (MBC) and microbial biomass N (MBN) were observed in winter under each forest. Microbial C use efficiency, measured as the metabolic quotient (qCO2 = CO2/MBC), varied strongly between forest stands and seasons but was generally higher in winter. The significant positive correlations between litter layer and microbial biomass C/N ratios, under beech and cedar forests, suggested strong CN stoichiometric coupling and microbial adaptation to substrate resource stoichiometry. qCO2 correlated significantly negatively with litter layers' temperature, positively with moisture content and EC. However, qCO2 had significant negative relationships with pH in pine and beech forests but significant positive under cedar forest. qCO2 showed significant positive relationships with C/N ratios under all forests but much stronger in beech and cedar forests suggesting higher C respired per unit MBC with an increase in C/N ratio. Despite variations between forest species, the highest MBC/TOC and MBN/TN ratios in fall indicated greater C and N incorporation into microbial biomass. Changes in MBC/MBN ratios under pine (9.62-10.6), beech (8.63-15.6), and cedar (7.32-16.2) forests indicated the shift in microbial communities as fungi have a higher C/N ratio than bacteria. Stepwise regression analysis further revealed that microbial respiration and biomass were controlled differently by litter layer characteristics in each forest. This study suggested that qCO2 independently or with other microbial indices can show litter layers' controls on organic matter turnover in Karst ecosystems and, taking into account the strong seasonal variations, can enhance the predictive potential of decomposition models.

Wattle fencing improved soil aggregate stability, organic carbon stocks and biochemical quality by restoring highly eroded mountain region soil.

Eroded bare land stabilization is important to reduce soil erosion and stimulate soil carbon (C) sequestration for improved soil biogeochemical quality in hillslope soils. This study investigated the effectiveness of wattle fencing as a bioengineering tool to improve soil stabilization, soil physico-chemical properties and soil organic C dynamics and reduce soil erodibility in the Boyabat mountain regions of Turkey with rough and over-steepened slope (50-70%). Wattle fence treatments were developed in the area of 50 ha in the spring season of 2010 and surface (0-20 cm) and subsurface soil (20-40 cm) samples were taken in Spring, 2015. Results revealed that, compared to control with bare slope, wattle fencing significantly improved some soil physico-chemical, and microbial properties and erodibility indices by increasing clay ratio, dispersion ratio and aggregate stability index in surface and subsoils. Wattle fencing enhanced plant available water contents more in surface than in subsoils. Wattle fencing also increased microbial biomass C contents by 55% and 43% in surface and subsurface soils, respectively. Soil organic C followed similar trends; however, they were indifferent between sampling depths for the control soils. Soil organic C stocks and aggregate stability index were significantly positively correlated and seemed to be better predictor of positive effects of wattle fencing on soil structural stability, erodibility and associated properties. We found positive effects of soil organic C contents on microbial biomass C and soil-water relations suggesting restoration of soil biological functions and favorable influence on soil water retention following wattle fencing. Although sparse vegetation was observed in the research area, our study emphasizes performing further research to understand the effects of wattle fencing along with afforestation with native vegetation on soil erosion rates on a long-term basis by considering the variability in edaphic and environmental factors.