Effects of parent material on soil erosion within Mediterranean new vineyard plantations

Highlights

• Parent material is key factor that determines soil erosion.

• ISUM (improved stock unearthing method) was applied on colluvium and marls.

• Marls (8-years old) resulted in a total soil losses of −87.7 Mg ha year⁻¹

• Colluvium (2-years old) reached a total soil losses of −4.35 Mg ha year⁻¹

Abstract

Parent material can determine specific physical and chemical soil properties and, therefore, soil erosion rates. However, for new vine plantations, there is not enough research on soil erosion assessment on different parent materials which could be helpful for agricultural management plans. The main aim of this research was to quantify soil erosion rates of two recent vineyard plantations under similar climate and land use management conditions, but on different parent materials, namely colluvium (2 years old) and marls (8 years old), located within the Les Alcusses valley vineyards in Eastern Spain. To achieve this goal, the ISUM (improved stock unearthing method) was applied. ISUM involves measurements of vertical distances from a horizontally stretched meter band attached to opposite pair vine plants to the topsoil surface at 5 sampling points along the cross sections of the pair vine rows. The original surface level was determined from the fixed distance of 2 cm of the graft unions from the soil surface. Digital elevation modelling of the vertical measurements was used to infer the erosion rates. Annual total soil erosion rates were 87.7 Mg ha⁻¹ year⁻¹ and 4.35 Mg ha⁻¹ year⁻¹ in the marls and colluvium plots, respectively. For the marls plot, 67% of the depletion occurred in the inter-row areas, whereas for the colluvium plot the inter-row areas registered 4.78 Mg ha⁻¹ year⁻¹ depletion and the row areas showed only a deposition of 0.44 Mg ha⁻¹ year⁻¹. We hypothesised that the inter-row areas registered the highest erosion rates due to the tillage practices. In the row areas, the cover of the vines possibly reduced soil erosion rates and acted as sinks for sediments. This behaviour of the inter-row areas acting as sources and the row areas as sinks for sediments was more evident on the colluvium plot, while most sections on the marls plot showed intense erosion features. It is suggested that more attention should be paid by policymakers and stakeholders to these differences when new plantations are introduced on marls and colluvium vineyards. We claim that initial soil erosion control measures should be applied during the first few years of plantations instead of when the vineyards are much older and soil has already been mobilised.

Introduction

Parent material is a key factor that determines the main physical and chemical properties of a soil (Chesworth 1973; Osher and Buol 1998). Soil scientists have accepted this fact as a universal law. Notable examples of soil scientists who have paid attention to the effects of the parent material on soil properties include Brimhall et al. (1991), Driese et al. (2003), Muhs et al. (2001), Rawlins et al. (2003) and Yesilonis et al. (2008). Within the Earth Sciences, the effect of parent material on soil processes was confirmed when a holistic view was applied by means of the biochemical cycle approach (Anderson 1988).

It is well-known that soil formation is a consequence of the weathering of the rocks, the decomposition of the organic matter and the turnover of the materials, minerals, water, organic matter, air and life, which result in the horizon formation (Wagai et al. 2008; Duchaufour 1997; Fitzpatrick 1980; Chesworth 1973). Moreover, some specific soil degradation phenomena occur in connection with certain parent materials due to the abundance of other environmental and anthropogenic factors which reduce soil depths, organic matter, biota activity, water retention capacity, and fertility (Orgill et al. 2017).

Soil erosion is a key process that determines the soil fate in natural ecosystems, and parent material again plays a key role as it determines soil erosion processes and rates (Cerdà, 1999, Cerdà, 2002), soil erodibility, surface topography and landforms (Bryan et al. 1989; Bryan 2000). However, little attention has been paid to other topics such as the biotic (mainly plants' effects on soil erosion), hydric (rainfall and runoff effect on sediment delivery), soil properties and land management impact on soil erosion in relation to the parent material and the age of plantation.

This brief description of the state-of-the-art underscores the importance of parent material on soil processes. However, there is little research on the effects of parent material on soil erosion (Mohammadkhan et al. 2011; Pennock et al. 1995; Weaver, 1991), the evolution of the biological properties (Braithwaite et al. 1984; Ulrich and Becker 2006) and availability of nutrients (Yavitt 2000; Yesilonis et al. 2008). The role that parent materials play in soil erosion is also relevant to understanding the fate of the soils, their formation, and degradation (Nazari Samani et al. 2016; Orgill et al. 2017). Therefore, the need for researching the role of parent materials on soil erosion and other associated processes cannot be overstated.

The importance of parent material is especially relevant on bare soils devoid of protective vegetation cover such as in recently afforested areas and planted orchards (Corti et al. 2011). The lack of vegetation allows the parent material to be a driving factor of soil erosion (Atucha et al. 2013; Lombardi et al. 2017). This is very relevant in agricultural land such as vineyards, where the lack of vegetation due to tillage and the use of herbicides results in high erosion rates that are dependent on the parent material type. It is noted that the soil horizon development and soil biomass composition are highly dependent on soil formation and degradation processes (Cattanio 2017; Foltz et al. 2011). Among the degradation processes, soil erosion is the severest threat as it removes soil mass. In agricultural lands, and specifically in conventional vineyards with partially bare soils in young plantations, the impact of parent material on soil erosion is highly relevant due to low vegetative cover and low root development, but it is in many instances ignored. Recently, the negative impact of the age of plantations has been highlighted, but only the parent material was mentioned with little information on age (Rodrigo-Comino et al. 2018a; Cerdà et al. 2017). Another key factor studied at great lengths in the literature is the control that vegetation exerts on soil erosion (Martínez-Casasnovas et al. 2009). The vegetation cover and the age of plantation is highly controlled by the climate but also influenced by human activities such as agriculture. Different land management strategies have been widely investigated during the last decade though (Berland et al. 2017; Dawson et al. 2017).

In European vineyards, where intensive tillage with machinery (Arnaez et al. 2007) or herbicide applications (Salomé et al. 2016) have resulted in bare soils, the parent material has become one of the most relevant key factors of terroir characterisation (Vaudour 2002; Vaudour et al. 2015), but its effect on different lithological groups has not been highlighted. Within Mediterranean vineyards, soil erosion has been studied in facies such as sedimentary (Quiquerez et al. 2008; Martínez-Casasnovas et al. 2009) and metamorphic materials (Biddoccu et al. 2017a) with bare soils. All tested soils demonstrated that vegetation cover reduces the soil and water losses to some degree depending on the percentage cover. However, long-term monitoring at the pedon scale of the influence of the parent material on soil erosion rates in new plantations is rare.

The main goal of this research is to quantify soil mobilisation rates and micro-topographical changes on two different parent materials (colluvium and marls) within two vineyards using the improved stock unearthing method (ISUM). We intend to demonstrate the impacts of age of plantations under the same land use management and climate conditions on erosion.

Although, water erosion is commonly observed on steeper slopes (slope angles >16^o) rather than on conventional mild slope terraces (slope angle <5°), previous research showed that intense ploughing, use of pesticides, herbicides and fungicides, and extreme rainfall events can cause high soil erosion rates in vineyards of both mild and steep slope terraces (Ramos and Porta 1997, slope angles >16^o; Sofia and Tarolli 2017, slope angles 2°–9°). Therefore, we decided to conduct our research in two conventional vineyards at the Les Alcusses valley, in Eastern Spain, that contain small terraces with moderate slopes supported by long rows of plants. We hypothesise that, although both plots of different ages are producing high amounts of grapes, the degradation processes on the older plot are increased due to erosion. Therefore, the identification of a little-known driving factor of soil erosion, namely the age of plantations or different parent material, may be useful for the development of nature based-solutions and land management plans.