Modelling soil organic carbon changes under different maize cropping scenarios for cellulosic ethanol in Europe

The utilization of crop residues in the production of second generation biofuels has the potential to boost the bioenergy sector without affecting food commodity prices. However, policies leading to large-scale biomass removal should carefully balance the consequences, both environmental and in terms of emissions, on soil organic carbon (SOC) stocks depletion. Using a recently developed simulation platform, SOC changes were estimated at European level (EU + candidate and potential candidate countries) under two scenarios of low (R30) and high (R90) maize stover removal for cellulosic ethanol production (i.e. 30% and 90% of stover removal, respectively). Additionally, mitigation practices for SOC preservation, namely the introduction of a ryegrass cover crop (R90_C) and biodigestate return to soil (R90_B), were explored under the highest rate of stover removal. The results showed that 15.3 to 50.6 Mt yr-1 of stover (dry matter) would be potentially available for ethanol production under the lower and high removal rates considered. However, large-scale exploitation of maize residues will lead to a SOC depletion corresponding to 39.7 – 135.4 Mt CO2 eq. by 2020 (under R30 and R90, respectively) with greater losses in the long-term. In particular, every tonne of C residue converted to bioethanol was predicted to have an additional impact on SOC loss almost ranging from 0.2-0.5 CO2 eq ha-1 yr-1, considering a continuous biofuel scenario by 2050. The mitigation practices evaluated could more than halve SOC losses compared to R90, but not totally offsetting the negative soil C balance. There is a pressing need to design policies at EU level for optimum maize biofuel cultivations that will preserve the current SOC stock or even generate C credits.JRC.H.5-Land Resources Managemen

A New Assessment of Soil Loss Due to Wind Erosion in European Agricultural Soils Using a Quantitative Spatially Distributed Modelling Approach

Field measurements and observations have shown that wind erosion is a threat for numerous arable lands in the European Union (EU). Wind erosion affects both the semi-arid areas of the Mediterranean region as well as the temperate climate areas of the northern European countries. Yet, there is still a lack of knowledge, which limits the understanding about where, when and how heavily wind erosion is affecting European arable lands. Currently, the challenge is to integrate the insights gained by recent pan-European assessments, local measurements, observations and field-scale model exercises into a new generation of regional-scale wind erosion models. This is an important step to make the complex matter of wind erosion dynamics more tangible for decision-makers and to support further research on a field-scale level. A geographic information system version of the Revised Wind Erosion Equation was developed to (i) move a step forward into the large-scale wind erosion modelling; (ii) evaluate the soil loss potential due to wind erosion in the arable land of the EU; and (iii) provide a tool useful to support field-based observations of wind erosion. The model was designed to predict the daily soil loss potential at a ca. 1 km2 spatial resolution. The average annual soil loss predicted by geographic information system Revised Wind Erosion Equation in the EU arable land totalled 0·53 Mg ha−1 y−1, with the second quantile and the fourth quantile equal to 0·3 and 1·9 Mg ha−1 y−1, respectively. The cross-validation shows a high consistency with local measurements reported in literature

LUCAS 2018 - SOIL COMPONENT: Sampling Instructions for Surveyors

The European Commission launched a soil assessment component to the periodic LUCAS Land Use/Land Cover Area Frame Survey in 2009. Composite soil samples from 0-20-cm depth were taken, air-dried and sieved to 2 mm in order to analyse physical and chemical parameters of topsoil in 25 Member States (EU-27 except Bulgaria, Romania, Malta and Cyprus). The aim of the LUCAS Soil Component was to create a harmonised and comparable dataset of main properties of topsoil at the EU. The LUCAS Soil Component was extended to Bulgaria and Romania in 2012. Overall, ca. 22,000 soil samples were collected and analysed. All samples were analysed for percentage of coarse fragments, particle-size distribution, pH, organic carbon, carbonates, phosphorous, total nitrogen, extractable potassium, cation exchange capacity, multispectral properties and heavy metals. In 2015, the soil sampling was repeated in the same set of points of LUCAS 2009/2012 to monitor changes in topsoil physical and chemical parameters across the EU. The soil component was extended to points above elevations of 1000 m, which were not sampled in LUCAS 2009/2012. Furthermore, soil samples were taken in Albania, Bosnia-Herzegovina, Croatia, Macedonia, Montenegro, Serbia and Switzerland. The soil sampling was carried out following the instructions already used in LUCAS 2009/2012. Approximately 27,000 samples were collected and will be analysed during 2016 and 2017. In 2018, a new soil sampling campaign will be carried out within the LUCAS framework. Soil samples will be taken in repeated points of LUCAS 2009/2012 and LUCAS 2015. The novelty of the survey is that new physical, chemical and biological parameters will be analysed. Key parameters for evaluating soil quality, such as bulk density and soil biodiversity, will be analysed. These analyses require specific methods of soil sampling, preparation and storage of samples. Furthermore, field measurements such as the thickness of organic layer in peat soils, and visual assessment of signs of soil erosion will be carried out in 2018. This technical report compiles the instructions for collecting the various soil samples and for performing field measurements in the soil survey of 2018. These instructions will be used for all LUCAS surveyors, to create a comparable database of soil characteristics all over Europe.JRC.D.3-Land Resource

Effect of Good Agricultural and Environmental Conditions on erosion and soil organic carbon balance: A national case study

Since, the Common Agricultural Policies (CAP) reform in 2003, many efforts have been made at the European level to promote a more environmentally friendly agriculture. In order to oblige farmers to manage their land sustainably, the GAEC (Good Agricultural and Environmental Conditions) were introduced as part of the Cross Compliance mechanism. Among the standards indicated, the protection of soils against erosion and the maintenance of soil organic matter and soil structure were two pillars to protect and enhance the soil quality and functions. While Member States should specifically define the most appropriate management practices and verify their application, there is a substantial lack of knowledge about the effects of this policy on erosion prevention and soil organic carbon (SOC) change. In order to fill this gap, we coupled a high resolution erosion model based on Revised Universal Soil Loss Equation (RUSLE) with the CENTURY biogeochemical model, with the aim to incorporate the lateral carbon fluxes occurring with the sediment transportation. Three scenarios were simulated on the whole extent of arable land in Italy: (i) a baseline without the GAEC implementation; (ii) a current scenario considering a set of management related to GAEC and the corresponding area of application derived from land use and agricultural management statistics and (iii) a technical potential where GAEC standards are applied to the entire surface. The results show a 10.8% decrease, from 8.33 Mg ha −1 year −1 to 7.43 Mg ha −1 year −1 , in soil loss potential due to the adoption of the GAEC conservation practices. The technical potential scenario shows a 50.1% decrease in the soil loss potential (soil loss 4.1 Mg ha −1 year −1 ). The GAEC application resulted in overall SOC gains, with different rates depending on the hectares covered and the agroecosystem conditions. About 17% of the SOC change was attributable to avoided SOC transport by sediment erosion in the current scenario, while a potential gain up to 23.3 Mt of C by 2020 is predicted under the full GAEC application. These estimates provide a useful starting point to help the decision-makers in both ex-ante and ex-post policy evaluation while, scientifically, the way forward relies on linking biogeochemical and geomorphological processes occurring at landscape level and scaling those up to continental and global scales

Climate change impacts of power generation from residual biomass

The European Union relies largely on bioenergy to achieve its climate and energy targets for 2020 and beyond. We assess, using Attributional Life Cycle Assessment (A-LCA), the climate change mitigation potential of three bioenergy power plants fuelled by residual biomass compared to a fossil system based on the European power generation mix. We study forest residues, cereal straws and cattle slurry. Our A-LCA methodology includes: i) supply chains and biogenic-CO2 flows; ii) explicit treatment of time of emissions; iii) instantaneous and time-integrated climate metrics. Power generation from cereal straws and cattle slurry can provide significant global warming mitigation by 2100 compared to current European electricity mix in all of the conditions considered. The mitigation potential of forest residues depends on the decay rate considered. Power generation from forest logging residues is an effective mitigation solution compared to the current EU mix only in conditions of decay rates above 5.2% a−1. Even with faster-decomposing feedstocks, bioenergy temporarily causes a STR(i) and STR(c) higher than the fossil system. The mitigation potential of bioenergy technologies is overestimated when biogenic-CO2 flows are excluded. Results based solely on supply-chain emissions can only be interpreted as an estimation of the long-term (>100 years) mitigation potential of bioenergy systems interrupted at the end of the lifetime of the plant and whose carbon stock is allowed to accumulate back. Strategies for bioenergy deployment should take into account possible increases in global warming rate and possible temporary increases in temperature anomaly as well as of cumulative radiative forcing

A step towards a holistic assessment of soil degradation in Europe: Coupling on-site erosion with sediment transfer and carbon fluxes

Soil degradation due to erosion is connected to two serious environmental impacts: (i) on-site soil loss and (ii) off-site effects of sediment transfer through the landscape. The potential impact of soil erosion processes on biogeochemical cycles has received increasing attention in the last two decades. Properly designed modelling assumptions on effective soil loss are a key pre-requisite to improve our understanding of the magnitude of nutrients that are mobilized through soil erosion and the resultant effects. The aim of this study is to quantify the potential spatial displacement and transport of soil sediments due to water erosion at European scale. We computed long-term averages of annual soil loss and deposition rates by means of the extensively tested spatially distributed WaTEM/SEDEM model. Our findings indicate that soil loss from Europe in the riverine systems is about 15% of the estimated gross on-site erosion. The estimated sediment yield totals 0.164 ± 0.013 Pg yr−1 (which corresponds to 4.62 ± 0.37 Mg ha−1 yr−1 in the erosion area). The greatest amount of gross on-site erosion as well as soil loss to rivers occurs in the agricultural land (93.5%). By contrast, forestland and other semi-natural vegetation areas experience an overall surplus of sediments which is driven by a re-deposition of sediments eroded from agricultural land. Combining the predicted soil loss rates with the European soil organic carbon (SOC) stock, we estimate a SOC displacement by water erosion of 14.5 Tg yr−1 . The SOC potentially transferred to the riverine system equals to 2.2 Tg yr−1 (~15%). Integrated sediment delivery-biogeochemical models need to answer the question on how carbon mineralization during detachment and transport might be balanced or even off-set by carbon sequestration due to dynamic replacement and sediment burial

Phosphorus plant removal from European agricultural land

AbstractPhosphorus (P) is an important nutrient for all plant growth and it has become a critical and often imbalanced element in modern agriculture. A proper crop fertilization is crucial for production, farmer profits, and also for ensuring sustainable agriculture. The European Commission has published the Farm to Fork (F2F) Strategy in May 2020, in which the reduction of the use of fertilizers by at least 20% is among one of the main objectives. Therefore, it is important to look for the optimal use of P in order to reduce its pollution effects but also ensure future agricultural production and food security. It is essential to estimate the P budget with the best available data at the highest possible spatial resolution. In this study, we focused on estimating the P removal from soils by crop harvest and removal of crop residues. Specifically, we attempted to estimate the P removal by taking into account the production area and productivity rates of 37 crops for 220 regions in the European Union (EU) and the UK. To estimate the P removal by crops, we included the P concentrations in plant tissues (%), the crop humidity rates, the crop residues production, and the removal rates of the crop residues. The total P removal was about 2.55 million tonnes (Mt) (± 0.23 Mt), with crop harvesting having the larger contribution (ca. 94%) compared to the crop residues removal. A Monte-Carlo analysis estimated a ± 9% uncertainty. In addition, we performed a projection of P removal from agricultural fields in 2030. By providing this picture, we aim to improve the current P balances in the EU and explore the feasibility of F2F objectives

Assessment of changes in topsoil properties in LUCAS samples between 2009/2012 and 2015 surveys

Soil delivers fundamental ecosystem services that support human well-being. These include the provision of food, feed, fuel, fibre and genetic resources, the regulation of storage, filtration and cycling of nutrients and water, cultural (aesthetic, spiritual and recreational) values and supporting the provision of all other services. Policies for sustainable land and soil management should be based on monitoring systems that are able to provide evidence of the impact of land use/land cover changes and climate change in soil condition, both in space and in time. In this context, the topsoil assessment module of the Land Use and Cover Area Frame Survey (LUCAS) is the first harmonised soil monitoring network at European Union (EU) level that uses a common sampling procedure and standard analysis methods. Eurostat has carried out the LUCAS survey every 3 years since 2006. The surveys are based on the visual assessment of environmental and structural elements of the landscape in georeferenced control points, a subsample of which is selected to be visited to collect field-based information. In 2009, a soil assessment module was added within the LUCAS survey with the scope to create a harmonised and comparable dataset of physical and chemical properties of topsoil across the EU to support policymaking. About 20,000 soil points were selected across 27 member states (except Bulgaria and Romania) based on a stratified sampling scheme with land use and terrain information as attributes. At each point, samples were collected from a depth of 20 cm using a common sampling procedure. Subsequently, the samples were analysed for several properties in a single laboratory using standard analytical methods. The same point selection procedure, sampling method and analysis methods were extended in 2012 to Bulgaria and Romania, where samples were collected for about 2,000 soil points. The LUCAS Topsoil Survey was repeated in 2015, year in which 17,613 soil points sampled in the LUCAS 2009 and 2012 surveys were revisited. Furthermore, new soil points at an altitude of 1,000 - 2,000 m were added to the survey (the altitude limit was 1,000 m in LUCAS 2009 and 2012 surveys). The soil module was also extended by the JRC to Albania, Bosnia and Herzegovina, Croatia, Montenegro, Republic of North Macedonia and Serbia. In total, 27,069 points were selected for the topsoil survey in 2015, of which 25,947 were located in the EU-28 MS. In this report, we provide a detailed evaluation of the LUCAS topsoil sampling and the laboratory analysis. We also assess changes in topsoil properties between LUCAS 2009/2012 and 2015 surveys based on data of paired samples (i.e. samples collected in revisited LUCAS soil points in 2009/2012 and in 2015). The ultimate goal of this report is to assess the efficacy of the LUCAS Topsoil Module for the early detection of changes in soil conditions, since this is a primary objective for scientific and policy organizations to improve their policies for a sustainable land use and management. The LUCAS spade sampling is an efficient and cost-effective method for topsoil monitoring at regional/continental scale, although a better control of litter removal in woodland and sampling depth in all LC classes is needed. When comparing sampling locations of revisited points, almost 97 % of the samples taken in 2015 were taken at a distance <100 m from their baseline locations in 2009/2012 as indicated in the sampling protocol. Three percent of the samples were taken at a distance between 100 and 400 m from one survey to the other. As a result, changes in soil properties were not significantly affected by the distance between sampling locations in the 2009/2012 and 2015 surveys. Regarding laboratory analysis, the data of the properties analysed showed a coherence from the soil point of view. Organic carbon and N levels showed a positive correlation, CaCO3 content was lower in samples were pH was below 7, and the sum of sand, silt and clay percentages was between 99 and 101 in the fraction <2 mm of all samples. Overall, OC and N levels were highest in woodland, followed by grassland and cropland in both the 2009/2012 and 2015 surveys. On the contrary, P and K levels were higher in cropland and grassland than in woodland in the surveys. Carbonate content was lowest in woodland from northern member states and highest in cropland from southern member states in both surveys. In agreement with these results, pH was lower in woodland than in cropland in both surveys. Soil properties showed large standard deviations within surveys and between surveys due to uncertainties arising from the sampling. Unfortunately, some LC classes were under sampled. Consideration should be given to increase the number of sampling sites in future surveys to ensure representative data. Overall, most of the soil properties showed limited changes between 2009 and 2015 (over the six-year period) in the 27 member states. Changes in Bulgaria and Romania were even less evident over the three-year period (from 2012 to 2015). Thus, the survey confirms that soil properties change very slowly over time. From a policy perspective, a time lapse longer than six years is necessary in order to observe small variations in soil conditions, unless a marked change has occurred due to erosion processes, extreme meteorological events or land use/cover changes. Despite uncertainties arising from the sampling, it has been possible to draw some conclusions when assessing changes in soil properties between 2009/2012 and 2015 surveys in mineral soils (i.e. where OC <120 g kg-1). — Taking the revisited points, a statistically significant increase in OC content of 3.74 % was observed in grassland over six years in the 27 member states. This is in line with the annual 0.4 % increase in the topsoil (30-40 cm) targeted by the ‘4 per 1000’ initiative. This would contribute to climate change mitigation. — Similarly, for the revisited points in cropland, a statistically significant decrease in OC content of 2.5 % was observed while points that changed from grassland to cropland over six years decreased by 11 %. This suggests that cropland soils are not working as carbon sinks. — In other land cover categories, the number of repeated points was insufficient to assess statistical significance. — No tangible changes were observed in Bulgaria and Romania over three years. — Nitrogen content increased in cropland, grassland, woodland points, and in points that changed from cropland to grassland over six years in the 27 member states. In Bulgaria and Romania, N content increased in cropland points and in points that changed from cropland to grassland and vice-versa over three years. In non-agricultural conditions, this may reflect airborne deposition of nitrogen. — Phosphorus content increased in cropland, grassland and woodland points over six years in the 27 member states. On the contrary, K content decreased in cropland points in the 27 member states. In Bulgaria and Romania, no tangible changes were observed over three years. — pH in CaCl2 was a more consistent measurement and was less affected by seasonal fluctuations of electrolyte concentration in soil solution. — pH in CaCl2 increased in cropland and woodland points, and in points that changed from woodland to shrubland over six years in the 27 member states. On the contrary, pH in CaCl2 decreased in grassland points. In Bulgaria and Romania, pH in CaCl2 decreased in grassland points over three years.JRC.D.3-Land Resource

Soil erosion is unlikely to drive a future carbon sink in Europe

Acknowledgements: The work was carried out as part of the JRC's Institutional Work Programme under the Natural Capital Soil Project (Project 702), Work Package 5037 “Soil for Climate Change”. We thank Irene Biavetti for her graphical support in designing Fig. 2. Data and materials availability: All data needed to evaluate the conclusions in the paper are available at the European Soil Data Centre (ESDAC) of the European Commission – Joint Research Centre: http://esdac.jrc.ec.europa.eu/. Additional data related to this paper may be requested from the authors.Peer reviewedPublisher PD

How does tillage intensity affect soil organic carbon? A systematic review protocol

Background Soils contain the greatest terrestrial carbon (C) pool on the planet. Since approximately 12% of soil C is held in cultivated soils, management of these agricultural areas has a huge potential to affect global carbon cycling; acting sometimes as a sink but also as a source. Tillage is one of the most important agricultural practices for soil management and has been traditionally undertaken to mechanically prepare soils for seeding and minimize effects of weeds. It has been associated with many negative impacts on soil quality, most notably a reduction in soil organic carbon (SOC), although still a matter of considerable debate, depending on factors such as depth of measurement, soil type, and tillage method. No tillage or reduced intensity tillage are frequently proposed mitigation measures for preservation of SOC and improvement of soil quality, for example for reducing erosion. Whilst several reviews have demonstrated benefits to C conservation of no till agriculture over intensive tillage, the general picture for reduced tillage intensity is unclear. This systematic review proposes to synthesise an extensive body of evidence, previously identified through a systematic map. Methods This systematic review is based on studies concerning tillage collated in a recently completed systematic map on the impact of agricultural management on SOC restricted to the warm temperate climate zone (i.e. boreo-temperate). These 311 studies were identified and selected systematically according to CEE guidelines. An update of the original search will be undertaken to identify newly published academic and grey literature in the time since the original search was performed in September 2013. Studies will be critically appraised for their internal and external validity, followed by full data extraction (meta-data describing study settings and quantitative study results). Where possible, studies will be included in meta-analyses examining the effect of tillage reduction (‘moderate' (i.e. shallow) and no tillage relative to ‘intensive' tillage methods such as mouldboard ploughing, where soil is turned over throughout the soil profile). The implications of the findings will be discussed in terms of policy, practice and research along with a discussion of the nature of the evidence base