Rachel E. Creamer

Indicators for Monitoring Soil Biodiversity

A Bispo,3 D Cluzeau,4 R Creamer,1 M Dombos,I U Graefe,# PH Krogh,33 JP Sousa,44 G Peres,4 M Rutgers,11 A Winding,33 and J Rombke*II 7French Agency for Environment and Energy Management, France 8University of Rennes, France 6Teagasc, Ireland IResearch Institute for Soil Science and Agricultural Chemistry, Hungary #Institut fur Angewandte Bodenbiologie, Germany 77Aarhus University, Denmark 88University of Coimbra, Portugal 66National Institute for Public Health and the Environment, Netherlands IIECT Oekotoxikologie GmbH, Germany * J-Roembke@ect.de

The practicalities and pitfalls of establishing a policy‐relevant and cost‐effective soil biological monitoring scheme

A large number of biological indicators have been proposed over the years for assessing soil quality. Although many of those have been applied in monitoring schemes across Europe, no consensus exists on the extent to which these indicators might perform best and how monitoring schemes can be further optimized in terms of scientific and policy relevance. Over the past decade, developments in environmental monitoring and risk assessment converged toward the use of indicators and endpoints that are related to soil functioning and ecosystem services. In view of the proposed European Union (EU) Soil Framework Directive, there is an urgent need to identify and evaluate indicators for soil biodiversity and ecosystem services. The recently started integrated project, Ecological Function and Biodiversity Indicators in European Soils (EcoFINDERS), aims to address this specific issue within the EU Framework Program FP7. Here, we 1) discuss how to use the concept of ecosystem services in soil monitoring, 2) review former and ongoing monitoring schemes, and 3) present an analysis of metadata on biological indicators in some EU member states. Finally, we discuss our experiences in establishing a logical sieve approach to devise a monitoring scheme for a standardized and harmonized application at European scale.

An inter-laboratory comparison of multi-enzyme and multiple substrate-induced respiration assays to assess method consistency in soil monitoring

The use of indicators in soil monitoring schemes to detect changes in soil quality is receiving increased attention, particularly the application of soil biological methods. However, to date, the ability to compare information from different laboratories applying soil microbiological techniques in broad-scale monitoring has rarely been taken into account. This study aimed to assess the consistency and repeatability of two techniques that are being evaluated for use as microbiological indicators of soil quality: multi-enzyme activity assay and multiple substrate-induced respiration (MSIR). Data were tested for intrinsic (within-assay plate) variation, inter-laboratory repeatability (geometric mean regression and correlation coefficient) and land-use discrimination (principal components analysis). Intrinsic variation was large for both assays suggesting that high replicate numbers are required. Inter-laboratory repeatability showed diverging patterns for the enzyme assay and MSIR. Discrimination of soils was significant for both techniques with relatively consistent patterns; however, combined laboratory discrimination analyses for each technique showed inconsistent correspondence between the laboratories. These issues could be addressed through the adoption of reliable analytical standards for biological methods along with adequate replication. However, until the former is addressed, dispersed analyses are not currently advisable for monitoring schemes.

Consequences of varied soil hydraulic and meteorological complexity on unsaturated zone time lag estimates.

The true efficacy of a programme of agricultural mitigation measures within a catchment to improve water quality can be determined only after a certain hydrologic time lag period (subsequent to implementation) has elapsed. As the biophysical response to policy is not synchronous, accurate estimates of total time lag (unsaturated and saturated) become critical to manage the expectations of policy makers. The estimation of the vertical unsaturated zone component of time lag is vital as it indicates early trends (initial breakthrough), bulk (centre of mass) and total (Exit) travel times. Typically, estimation of time lag through the unsaturated zone is poor, due to the lack of site specific soil physical data, or by assuming saturated conditions. Numerical models (e.g. Hydrus 1D) enable estimates of time lag with varied levels of input data. The current study examines the consequences of varied soil hydraulic and meteorological complexity on unsaturated zone time lag estimates using simulated and actual soil profiles. Results indicated that: greater temporal resolution (from daily to hourly) of meteorological data was more critical as the saturated hydraulic conductivity of the soil decreased; high clay content soils failed to converge reflecting prevalence of lateral component as a contaminant pathway; elucidation of soil hydraulic properties was influenced by the complexity of soil physical data employed (textural menu, ROSETTA, full and partial soil water characteristic curves), which consequently affected time lag ranges; as the importance of the unsaturated zone increases with respect to total travel times the requirements for high complexity/resolution input data become greater. The methodology presented herein demonstrates that decisions made regarding input data and landscape position will have consequences for the estimated range of vertical travel times. Insufficiencies or inaccuracies regarding such input data can therefore mislead policy makers regarding the achievability of water quality targets.

Making the Most of Our Land: Managing Soil Functions from Local to Continental Scale

The challenges of achieving both food security and environmental sustainability have resulted in a confluence of demands on land within the European Union (EU): we expect our land to provide food, fibre and fuel, to purify water, to sequester carbon, and provide a home to biodiversity as well as external nutrients in the form of waste from humans and intensive livestock enterprises. All soils can perform all of these five functions, but some soils are better at supplying selective functions. Functional Land Management is a framework for policy-making aimed at meeting these demands by incentivising land use and soil management practices that selectively augment specific soil functions, where required. Here, we explore how the demands for contrasting soil functions, as framed by EU policies, may apply to very different spatial scales, from local to continental scales. At the same time, using Ireland as a national case study, we show that the supply of each soil function is largely determined by local soil and land use conditions, with large variations at both local and regional scales. These discrepancies between the scales at which the demands and supply of soil functions are manifested, have implications for soil and land management: while some soil functions must be managed at local (e.g. farm or field) scale, others may be offset between regions with a view to solely meeting national or continental demands. In order to facilitate the optimisation of the delivery of soil functions at national level, to meet the demands that are framed at continental scale, we identify and categorise 14 policy and market instruments that are available in the EU. The results from this inventory imply that there may be no need for the introduction of new specific instruments to aid the governance of Functional Land Management. We conclude that there may be more merit in adapting existing governance instruments by facilitating differentiation between soils and landscapes.

Clay illuviation provides a long-term sink for C sequestration in subsoils

Soil plays a key role in the global carbon (C) cycle. Most current assessments of SOC stocks and the guidelines given by Intergovernmental Panel on Climate Change (IPCC) focus on the top 30 cm of soil. Our research shows that, when considering only total quantities, most of the SOC stocks are found in this top layer. However, not all forms of SOC are equally valuable as long-term stable stores of carbon: the majority of SOC is available for mineralisation and can potentially be re-emitted to the atmosphere. SOC associated with micro-aggregates and silt plus clay fractions is more stable and therefore represents a long-term carbon store. Our research shows that most of this stable carbon is located at depths below 30 cm (42% of subsoil SOC is located in microaggregates and silt and clay, compared to 16% in the topsoil), specifically in soils that are subject to clay illuviation. This has implications for land management decisions in temperate grassland regions, defining the trade-offs between primary productivity and C emissions in clay-illuviated soils, as a result of drainage. Therefore, climate smart land management should consider the balance between SOC stabilisation in topsoils for productivity versus sequestration in subsoils for climate mitigation.

A note on the Hybrid Soil Moisture Deficit Model v2.0

Abstract The Hybrid Soil Moisture Deficit (HSMD) model has been used for a wide range of applications, including modelling of grassland productivity and utilisation, assessment of agricultural management opportunities such as slurry spreading, predicting nutrient emissions to the environment and risks of pathogen transfer to water. In the decade since its publication, various ad hoc modifications have been developed and the recent publication of the Irish Soil Information System has facilitated improved assessment of the spatial soil moisture dynamics. In this short note, we formally present a new version of the model (HSMD2.0), which includes two new soil drainage classes, as well as an optional module to account for the topographic wetness index at any location. In addition, we present a new Indicative Soil Drainage Map for Ireland, based on the Irish Soil Classification system, developed as part of the Irish Soil Information System.

Application of Dexter’s soil physical quality index: an Irish case study

Abstract Historically, due to a lack of measured soil physical data, the quality of Irish soils was relatively unknown. Herein, we investigate the physical quality of the national representative profiles of Co. Waterford. To do this, the soil physical quality (SPQ) S-Index, as described by Dexter (2004a,b,c) using the S-theory (which seeks the inflection point of a soil water retention curve [SWRC]), is used. This can be determined using simple (S-Indirect) or complex (S-Direct) soil physical data streams. Both are achievable using existing data for the County Waterford profiles, but until now, the suitability of this S-Index for Irish soils has never been tested. Indirect-S provides a generic characterisation of SPQ for a particular soil horizon, using simplified and modelled information (e.g. texture and SWRC derived from pedo-transfer functions), whereas Direct-S provides more complex site-specific information (e.g. texture and SWRC measured in the laboratory), which relates to properties measured for that exact soil horizon. Results showed a significant correlation between S-Indirect (Si) and S-Direct (Sd). Therefore, the S-Index can be used in Irish soils and presents opportunities for the use of Si at the national scale. Outlier horizons contained >6% organic carbon (OC) and bulk density (Bd) values <1 g/cm3 and were not suitable for Si estimation. In addition, the S-Index did not perform well on excessively drained soils. Overall correlations of Si. with Bd and of Si. with OC% for the dataset were detected. Future work should extend this approach to the national scale dataset in the Irish Soil Information System.

A History of Soil Research with Emphasis on Pedology

While commentary on the productivity of Irish pastures can be dated as far back as 55 BC, direct references to the different kinds of soil only begin in the eighth century AD. Early scientific information on Irish soils typically came from the endeavours of geologists or other professionals who studied rock and outcropping patterns. The Geological Survey of Ireland, a constituent of the Geological Survey of Great Britain and Ireland, developed small-scale county soil maps, largely for the southern counties in the mid-1800s. In relation to pedology, John Hodges, an Irish soil analyst described soil profiles in the 1850s in terms identical with those dated to the Dokuchaev School in 1880s Russia. Soil science in Ireland has typically been delivered with agricultural and environmental science at University level. Agricultural extension dates back to 1731 through the Dublin Society employment of itinerant instructors. The soil test, pioneered by P H Gallagher in the 1930s became the single most important tool for the advisory service. In their essays on the characteristics of Irish soil types he, together with Dr. Tom Walsh, laid the groundwork for future classification and mapping. In 1945, the Department of Agriculture established a research centre at Johnstown Castle, Co. Wexford. The soil division of An Foras Taluntais was headquartered there and the National Soil Survey of Ireland established. In 1980 the second edition, General Soil Map of Ireland, was published. This survey was discontinued in 1988. In 1998, the Spatial Analysis Unit was established in Teagasc a key output of which was the first nationally complete digital subsoil and indicative soil map in 2009. Not long after, the 3rd Edition National Soil Map of Ireland was launched in 2014, through the collaboration of the Spatial Analysis Unit and Teagasc Johnstown Castle.

Soils and Productivity

This chapter explores the predominant land-based production systems in Ireland, specifically describing grassland, arable and forestry production. Grass is the most important agricultural crop in Ireland representing the main feed source for the livestock sector. Arable production represents a relatively small area, largely due to excess soil moisture conditions that are typical of many Irish soils. Despite favourable conditions for forestry in Ireland, the level of forest cover is low by European standards and has historically been associated with sub-marginal and marginal agricultural land. The importance of soil structure in the provision of nutrients, water and air is emphasised along with best management practices in relation to the management cycle. The role of soil texture is outlined, as is the agroclimate and soil interaction in Irish soils. The agricultural drainage conditions of Irish soils fall into the temperate zone, where the main role of drainage is the removal of excess water in the root zone of crops from surplus rainfall. This follows with a historical account of land drainage schemes in Ireland. Finally, the issues of the main production systems on poorly drained soils and the cultural practices to maintain trafficability are described. Improving the overall trafficability of any soil first requires the identification of factors causing either excessive moisture or poor soil structure. Correctly ascertaining these issues allows implementation of appropriate preventative and remediation measures, and should be the initial step in any management strategy.