Decomposition of paper de-inking sludge in a sandpit minesoil during its revegetation

Paper de-inking sludge was used as an organic amendment for revegetating an abandoned sandpit in Québec, Canada. In situ patterns of sludge decomposition and of total nitrogen and phosphorus dynamics were characterized in a litter bag study. In a one-time operation, sludge was applied at a rate of 0 or 105 Mg dry matter ha−1, along with N at 3, 6 or 9 kg Mg−1 sludge and P at 0.5 or 1.0 kg Mg−1 sludge. Sludge and fertilizers were incorporated into the top 0.21 m of the minesoil and tall wheatgrass (Agropyron elongatum (Host) Beauv.) was seeded. Mass loss was well described by a double exponential model when cumulative degree-days (sum of daily temperature above 0°C) were used as the independent variable. Fifty-one percent of the initial material decomposed with a half life of 0.4 yr, whereas the remaining material had a much slower rate of decay with a half life of 13 yr. The large size and slow decomposition rate of the recalcitrant pool of this material were attributed to the high lignin content and the presence of clay in the sludge. Both N and P in decomposing sludge presented a short accumulation phase followed by a long release phase which likely contributed to the successful revegetation of this disturbed sandpit site

How to measure, report and verify soil carbon change to realize the potential of soil carbon sequestration for atmospheric greenhouse gas removal

Global Change Biology published by John Wiley & Sons Ltd There is growing international interest in better managing soils to increase soil organic carbon (SOC) content to contribute to climate change mitigation, to enhance resilience to climate change and to underpin food security, through initiatives such as international ‘4p1000’ initiative and the FAO\u27s Global assessment of SOC sequestration potential (GSOCseq) programme. Since SOC content of soils cannot be easily measured, a key barrier to implementing programmes to increase SOC at large scale, is the need for credible and reliable measurement/monitoring, reporting and verification (MRV) platforms, both for national reporting and for emissions trading. Without such platforms, investments could be considered risky. In this paper, we review methods and challenges of measuring SOC change directly in soils, before examining some recent novel developments that show promise for quantifying SOC. We describe how repeat soil surveys are used to estimate changes in SOC over time, and how long-term experiments and space-for-time substitution sites can serve as sources of knowledge and can be used to test models, and as potential benchmark sites in global frameworks to estimate SOC change. We briefly consider models that can be used to simulate and project change in SOC and examine the MRV platforms for SOC change already in use in various countries/regions. In the final section, we bring together the various components described in this review, to describe a new vision for a global framework for MRV of SOC change, to support national and international initiatives seeking to effect change in the way we manage our soils

Identifying cost-competitive greenhouse gas mitigation potential of French agriculture

The agriculture, forestry and other land use sector are responsible for 24% (10–12 Pg CO2e per year) of anthropogenic greenhouse gas (GHG) emissions worldwide, with concomitant opportunities for mitigation. A scientific panel used deliberative methods to identify ten technical measures comprising 26 sub-measures to reduce GHG emissions from agriculture in France. Their abatement potential and cost are compared. The proposed measures concern nitrogen (N) management, management practices that increase carbon stocks in soils and biomass, livestock diets, and energy production and consumption on farms. Results show that the total abatement potential can be divided into three parts. One third of the cumulated abatement potential corresponds to sub-measures that can be implemented at a negative technical cost. These sub-measures focus on increased efficiency in input use including N fertilisers, animal feed and energy. The second third are sub-measures with moderate cost (€25 per metric Mg of avoided CO2e). These require investment with no direct financial return, the purchase of particular inputs, dedicated labour time or involve production losses. Assuming additivity, the cumulated abatement is 32.3 Tg CO2e per year in 2030, but only 10 Tg (i.e. 10% of current agricultural emissions) when calculated under current inventory rules. This study confirms that a significant abatement potential exists in the agricultural sector, with two thirds of this potential at low or even negative cost. This is likely to be an underestimated as it is based on a status quo of the current agricultural system. Results also emphasise the need to upgrade inventory rules so that efforts to reduce emissions can be accounted for

Uncovering Ubiquitin and Ubiquitin-like Signaling Networks

Microscopic imaging and technolog

The effects of cropping on aggregation and carbohydrates of a Kamouraska clay soil /

The main objective of this research was to determine the short-term effects of cropping on the aggregation and the carbohydrate fraction of a marine clay soil. When compared to a fallow (bare soil) control, cropping to barley and alfalfa for two seasons resulted in significant increases in the size and stability of soil aggregates. The increase in water-stable aggregates $>$2.0 mm was at the expense of aggregates $<$1.0 mm. Under corn, soil aggregation was not different than under fallow. After two seasons, soil under barley or alfalfa contained 15 to 25% more carbohydrates than the fallow or corn treatments. The partial correlation (r = 0.63, P = 0.001) which was observed between carbohydrate content and mean weight diameter of water-stable aggregates, and periodate oxidation tests strongly suggested that carbohydrates were at least partly responsible for the increase in macro-aggregate stability. The remaining cropping effects were removed by tetraborate which suggest the participation of more-humified though ill-defined organic matter. The nature of the changes in organic matter was further investigated using particle size fractionation. Compared to the fallow control, cropping to barley and alfalfa resulted in an enrichment in carbon, nitrogen, and carbohydrates in the sand fraction. The carbohydrate composition of the soil and of its size fractions, determined by liquid chromatography, suggested that cropping treatments had only little effect on the origin of the soil carbohydrates

Restoration of ecosystem function in an abandoned sandpit: plant and soil responses to paper de-inking sludge

1. In minesoil reclamation, the establishment of a sustainable plant cover requires the improvement of limiting conditions and the re-initiation of carbon (C) and nutrient cycling. 2. The approach used in this study for reclaiming an abandoned sandpit in Quebec, Canada, was based on a heavy organic amendment as an attempt to accelerate the reconstruction of a functional ecosystem. 3. The one-time intervention consisted of incorporating paper de-inking sludge into soil at two rates (0 and 105 dry t ha–1), supplemented with nitrogen (N) at three rates (3, 6 and 9 g kg–1 sludge) and phosphorus (P) at two rates (0·5 and 1·0 g kg–1 sludge) followed by seeding (mid-summer) of Agropyron elongatum (Host) Beauv. (tall wheatgrass). 4. Standing biomass increased in the presence of sludge after both the first and second full growing seasons. High N application rates further increased yield, more importantly in the second season. The high P rate improved grass establishment in all cases. Ground cover increased with time and doubled in the presence of sludge whereas it declined in the absence of sludge. Phosphorus and N uptake was improved consistently in the presence of sludge. 5. Sludge application resulted in improved water retention and cation exchange capacities, and an increase in pH and bulk density of sandpit minesoil, all of which may have accounted for the significant improvement in plant responses. Levels of soil C and N suggest that this reconstructed system is approaching sustainability. 6. Adequate N and P supplements will accentuate the positive influence of sludge on revegetation

Sound methods are needed to assess GHG mitigation potential of organic farming deployment. A comment on

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