J. Hydrol. Hydromech., 65, 2017, 4, 402–409 DOI: 10.1515/johh-2017-0022 Temporal changes in soil water erosion on sloping vineyards in the Ruwer- Mosel Valley. The impact of age and plantation works in young and old vines Jesús Rodrigo-Comino1, 2*, Christine Brings2, Thomas Iserloh2, Markus C. Casper2, Manuel Seeger2, José M. Senciales3, Eric C. Brevik4, José D. Ruiz-Sinoga1, 3, Johannes B. Ries1 1 Instituto de Geomorfología y Suelos, Department of Geography, University of Málaga, 29071, Málaga, Spain. 2 Department of Physical Geography, Trier University, D-54286 Trier, Germany. 3 Department of Geography, Málaga University, Campus of Teatinos s/n, 29071 Málaga, Spain. 4 Department of Natural Sciences, Dickinson State University, Dickinson, ND, USA. * Corresponding author. E-mail: [email protected] Abstract: It is well known that rainfall causes soil erosion in sloping German vineyards, but little is known about the effect of age of plantation on soil erosion, which is relevant to understand and design sustainable management systems. In the Ruwer-Mosel valley, young (1- to 4-years) and old (35- to 38-years after the plantation) vineyards were selected to assess soil and water losses by using two-paired Gerlach troughs over three years (2013–2015). In the young vineyard, the overland flow was 107 L m–1 and soil loss 1000 g m–1 in the year of the plantation, and decreased drastically over the two subsequent years (19 L m–1; 428 g m–1). In the old vineyard, soil (from 1081 g m–1 to 1308 g m–1) and water (from 67 L m–1 to 102 L m–1) losses were 1.2 and 1.63 times higher, respectively, than in the young vineyard. Keywords: Soil erosion; Old vineyard; Young vineyard; Rainfall; Tillage; Ruwer-Mosel valley. INTRODUCTION within plots, slopes and watersheds (Masselink et al., 2016; Sofia and Tarolli, 2017). The German viticulture region of the Mosel valley is situated Different strategies and methods have been applied in Euro- close to the northern European boundary for commercial grape pean viticulture regions to measure, quantify and monitor soil growing, which depends on favourable pedoclimatic conditions erosion processes, including: i) small portable rainfall simula- for winter survival and grape ripening (Ashenfelter and tors (Prosdocimi et al., 2016; Rodrigo Comino et al., 2015a; Storchmann, 2010). Climatic, geomorphologic and phenologi- 2015b); ii) erosion pins and sediment traps in closed plots (No- cal characteristics are the most studied natural conditions in vara et al., 2011; Ruiz-Colmenero et al., 2011); iii) botanical order to determine the quality of German vineyards (Fischer et benchmarks (Paroissien et al., 2010; Rodrigo Comino et al., al., 1999; Urhausen et al., 2011). The introduction of new plan- 2015b, 2016); iv) remote sensing (Mathews and Jensen, 2013; tations of vines and an increase in the occurrence of extreme Taylor et al., 2009); and v) predictive modelling (David et al., rainfall events are contributing to soil degradation processes on 2014). However, few researchers have focused on the temporal German hillslope vineyards. Vegetation cover protects soil and seasonal changes in soil erosion at different vine ages. against erosion runoff generation (Martínez-Casasnovas et al., The main goal of this study was to assess the role of water in 2009; Ruiz-Colmenero et al., 2013), but also it improves soil soil erosion processes on two paired plots with vineyards of quality (Hosseini et al., 2017; Salomé et al., 2016). This is different ages since plantation (1- to 4- and 35- to 38-year old relevant as soil can act as a natural filter for water and manage plots, called here young and old plantations, respectively) over biogeochemical cycles in a world affected by global changes three years to understand the seasonal and temporal changes in and searching for sustainable development (Keesstra et al., soil erosion. This strategy will inform us about the effect of 2012). However, vineyards typically try to avoid the growth of plantation on the total soil erosion over the life-span of a vine- weeds and ploughing soils to remove them is a common man- yard. agement strategy. Causes of soil erosion have been investigated for the Ruwer- MATERIALS AND METHODS Mosel valley by some authors (e.g. Hacisalihoglu, 2007; Rich- Study area ter, 1980; Rodrigo Comino et al., 2015a, 2015b, 2016). They concluded that: i) steep slopes (15–50°); ii) disturbance of the The studied area is located in the village of Waldrach (Ru- soil profile during plantation; iii) wheel traffic impacts due to wer-Mosel Valley, Rhineland-Palatinate, Germany; 49.7418N; the use of heavy machinery for tilling and ploughing; iv) high 6.7524E, Figure 1). The mean annual rainfall is 765 mm, and overland flow, which results in rills and ephemeral gullies; v) during the research period, the annual rainfalls were 902 mm tillage practices in the inter-rows; and vi) high silt content, (2013), 660 mm (2014) and 524 mm (2015). The highest values which enhances soil sealing, resulted in extremely high erosion are concentrated in the summer months (65–72 mm per month) rates. and the lowest values of monthly precipitation are between However, little is known about soil erosion and runoff gen- February and April (50–60 mm per month). The average annual eration at the plantation scale, which is relevant to improve temperature is 9.3°C, with average maximum values from June grape production, reduce the use of pesticides and fertilizers, to August (16.2–17.6°C) and minimum values from December and avoid losses of nutrients and water (García-Díaz et al., to January (1.5–2.3°C). The old and young vineyards are situat- 2017). This knowledge will also improve understanding of the ed on a single hillslope with an altitude from 200 to 300 m a.s.l. runoff generation mechanisms and the connectivity of the flows and slopes from 15° to 30°. The length of both plots ranged 402 The impact of age and plantation works in young and old vines (Ruwer-Mosel valley, Germany) Fig. 1. Study area in the Ruwer-Mosel Valley. Table 1. Soil analysis of physical and chemical properties. fore, no soil acidification trends were noted in the old vineyard. Even if the differences had been greater than 1, no soil acidifi- Old vineyards Young vineyards cation trend would have been noted in the old vineyard because Gravel (%) 37.9±4.8 59.7±5.1 the old vineyard pH was higher (more basic). On the other, a Fine material (%) 62.1±4.8 40.3±5.1 slight acidification trend was observed in the young vineyard. Sand (%) 26±3.1 26.8±6.9 Similar traditional soil tillage and vine training systems were Silt (%) 64.7±2.8 64.3±5.8 used in both vineyards. The grape variety is Riesling and the Clay (%) 9.3±1.4 8.9±1.3 yearly soil management consists of: i) a mechanical tilling of TOC (%) 7.9±3.6 6.1±3.2 the top layer (≈20 cm) before and after grape harvesting (spring CaCO3 (%) 0.9±0.3 1.2±0.3 and early autumn); ii) the use of mulch and grass covers, which EC (dS m-1) 0.3±0.2 0.4±0.2 range from about 20 cm along the inter-rows and under vines to pH (H O) 7.2±0.2 6.5±0.2 2 between 10–35 cm of height; iii) the use of vine training sys- pH (KCl) 6.4±0.2 6.5±0.3 Dif. 0.9±0.1 0±0.1 tems composed of a plantation framework about 0.9 m x 1.0 m; SWC (%; FC) 27.7±4.5 28.8±3.4 iv) redistributing a soil cover of slates to protect the surface SWC (%WP) 12.3±2.4 10.5±1.5 against cold temperatures; and, v) the application of sprays during spring and summer by helicopter. between 60 and 70 meters. Soils are classified as leptic-humic Regosols (IUSS Working Group WRB, 2014). Physical and Soil loss, runoff and sediment concentration measures using chemical soil properties are summarized in Table 1. Infor- Gerlach troughs mation about soil analysis procedures were explained in detail in Rodrigo Comino et al. (2016). Gerlach troughs were built, installed and utilized as sediment The highest stone content was observed in the young vine- collectors (Gerlach, 1967). Four sediment collectors with a yard (59.7±5.1%). In the old vineyard stone content was width of 150 cm were placed in the inter-rows and part of the rows (Fig. 2). Amounts of soil loss, surface flow and sediment 37.9±4.8%. Silt was the most common particle size at the study –1 site with an average of 64.7% in the old vineyard and 64.3% in concentration were calculated in g, L and g L , respectively. the young one. The sand content averaged 26% in the old plot The open soil erosion plots gave information about the soil (g) and 26.8% in the young one. Clay particles arranged from 8.9% and water losses (L) but the contributing area is uncertain. This is why the soil erosion rates or overland flow are shown in (young vineyard) to 9.3% (old vineyard). Soil textures were –1 –1 silty loam in both plots. High soil water content at field capaci- g m and L m , respectively. ty was documented for both areas, being close to 30%. At the Over a period of three years (2013–2015), two Gerlach wilting point, values decreased to 12.3% in the old vineyard troughs were located at the bottom of each studied crop.