Elsevier

Land Use Policy

Volume 92, March 2020, 104467
Land Use Policy

An indicator to reflect the mitigating effect of Common Agricultural Policy on soil erosion

https://doi.org/10.1016/j.landusepol.2020.104467Get rights and content

Highlights

  • This study presents the updated version LAND Use and Management model (LANDUM).

  • LANDUM estimates the effects of land use and management practices on soil erosion.

  • Recent developments of soil conservation across Europe (2010–2016) are analyzed.

  • In 2016, a decrease of C-factor of ca. -0.84 % compared to the 2010 was observed.

  • Insights on the effectiveness of the CAP regarding soil conservation are provided.

Abstract

This study presents the updated version of the recently published LANDUM model [Land Use Policy 48, 38–50 (2015)]. LANDUM is integrated into the 100 m resolution RUSLE-based pan-European soil erosion risk modelling platform of the European Commission. It estimates the effects of local land use and management practices on the magnitude of soil erosion across each NUTS2 region of the European Union. This is done based on a spatially explicit estimation of the so-called cover-management factor of (R)USLE family models which is also known as C-factor. In this updated version, the data on soil conservation measures (i.e., reduced tillage, cover crops and plant residues) reported in the latest EU Farm Structure Survey (2016) were integrated and elaborated in LANDUM in order to estimate the changes of the C-factor in Europe between 2010 and 2016. For 2016, a C-factor of 0.2316 for the arable land of the 28 Member States of the European Union was estimated. This implies an overall decrease of C-factor of ca. -0.84 % compared to the 2010 survey. The change in C-factor from 2010 to 2016 could be an indication for the effectiveness of Common Agricultural Policy (CAP) soil conservation measures in reducing soil erosion in Europe, especially key CAP policies such as Good Agricultural and Environmental Conditions and Greening.

Introduction

Understanding the importance of harmonized pan-European assessment tools to estimate soil loss by water erosion (Robinson et al., 2017), Joint Research Centre (JRC) of the European Commission launched the LAND Use and Management model (LANDUM) in 2015 (Panagos et al., 2015a). LANDUM is the land use and land management component of the 100 m resolution RUSLE-based pan-European soil erosion risk modelling platform (Panagos et al., 2015b). The integrated cover-management factor (C) covers all 28 Member States of the European Union, in total 4.38 million km2, incorporating the information collected in the 2010 EU Farm Structure Survey (FSS) (Panagos et al., 2015a). In the (R)USLE-type equations (Alewell et al., 2019), C-factor estimates (or simulates) the combined effect of all interrelated land cover and land management measures (Wischmeier and Smith, 1965). It ranges from 0 to 1 depending on the ground cover representing the soil loss ratio (SLR). Generally, C-factor values close to zero are typically found in areas with up to 100 % ground cover whereas values close to one are typical for a bare plot (no vegetation) with till up and down the slope which is taken as a reference condition (C-factor = 1) (Borrelli et al., 2018a). Accordingly, the SLR is inversely proportional to the soil surface cover because soil surface cover intercepts raindrops and hinders surface runoff by slowing down rainwater.

According to RUSLE handbook (Renard et al., 1997), C-factor is a product of five sub-factors, i.e. canopy, surface cover, surface roughness, prior land use and antecedent soil moisture. In large-scale modelling applications, the estimation of the multiple C-factor sub-factor parameters and their dynamic change over time has traditionally been the most challenging component of the USLE-type equations (Borrelli et al., 2016; Schönbrodt et al., 2010). This has been critical as the C-factor together with the conversation support practice factor (P, describe the anthropogenic influence on the soil erosion process) is the key parameter to understand the delta between potential erosion under pristine and actual land conditions. In other words, the effect of cropping and management practices (hereinafter also referred to as measures) on erosion rates.

To date, C-factor calculation for large-scale RUSLE-based modelling applications generally relies on simple attributions of C-factor values derived from land use literature, digital cover maps (Bakker et al., 2008; Märker et al., 2008; Borrelli et al., 2014, among others) or vegetation indices obtained from remote sensing (Schönbrodt et al., 2010; Zhang et al., 2011; Ganasri and Ramesh, 2016, among others). A review of existing techniques was recently published (Benavidez et al., 2018). LANDUM introduced a new hybrid approach based on information derived from experimental/ literature data combined with CORINE Land Cover (CLC) inventory, remote sensing data and agricultural inventory data to describe crop systems and management practices across Europe. This approach was subsequently replicated in the RUSLE-based Global Soil Erosion Modelling platform (GloSEM) (Borrelli et al., 2017).

This study aims to integrate the results of the 2016 EU Farm Structure Survey (FSS) in LANDUM in order to (i) derive a pan-European indicator on the recent developments of soil conservation practices across Europe (2010–2016) and (ii) estimate the effect of reduced tillage, cover crops and plant residues to reduce soil loss rates at NUTS2 and national level.

Section snippets

Material and methods

LANDUM model estimates annual C-factor values in arable and non-arable lands following two different approaches (Fig. 1). Lands such as bare rocks, wetlands, beaches, glaciers, water bodies and artificial areas are not taken into consideration given their negligible effect from a soil erosion prospective. Those non-erosive lands account c.a. 9.7 % of EU total lands. Arable and non-arable lands are spatially defined by pan-European CORINE Land Cover 2006 database (100 m cell size). The CORINE

C-factor map of 2016

The LANDUM-based modelling approach provides estimates of the RUSLE cover-management factor (also known as C-factor) on a 100 × 100 m grid cell basis for the erodible EU-28 land surface (ca. 0.39 billion cells; ∼3.9 million km2); covering ∼90.3 % of European Union’s land surface. Non-erodible surface (such as bare rocks, glaciers, large rivers, lakes, and urban areas) cover the remaining 9.7 % of the land surface and were described as ‘No Data’.

The average C-factor value predicted by LANDUM for

Conclusions

The LANDUM model integrates the best available pan-European datasets and estimates the RUSLE C-factor at NUTS2 level combining the extent, types and spatial distribution of crops, soil conservation measures, natural and semi-natural vegetation measured by satellite imaging with agricultural inventory data. The elaboration of the EU Farm Structure Survey data 2016 and CORINE Land Cover2012 in the GIS-based LANDUM model allowed to update the knowledge about the most recent changes in land use and

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    Within the research domain of soil erosion modelling, the (Revised) Universal Soil Loss Equation ((R)USLE) crop cover and management factor (C-factor) links a relative erosion risk to the on-site land management decisions such as the cultivated crop, tillage method and cover crop application (Wischmeier & Smith, 1978). The parameter itself, along with its encapsulated information, has determined it a useful index for the majority of multi-scale global modelling studies (Borrelli et al., 2021), as well as, for example, broad-scale policy evaluations of the impact of the Common Agricultural Policy on soil erosion in Europe (Borrelli & Panagos, 2020). The implication of the seasonal effect of vegetation is incorporated into the C-factor by combining the temporal distribution of rainstorm energy with the protective vegetation cover at each phase of the crop-growth and management cycle.

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