**Soil Erosion and Surface Runoff on Slopes in Mountain Environment Depending on Application Technique and Seed Mixture – A Case-Study**

Wilhelm Graiss and Bernhard Krautzer

*Department of Ecological Restoration and Forage Crop Breeding Agricultural Research and Education Centre Raumberg-Gumpenstein, Irdning Austria* 

### **1. Introduction**

192 Soil Erosion Studies

Walkley A; Black I A (1934). An examination of the effect of Degtjareff method for

Wuddivira M N (2008). Structural stability, hydraulic properties and erodibility of humid

Wuddivira M N; Stone R J; Ekwue E I (2009). Clay, organic matter, and wetting effects on

Zhang B; Horn R; Hallett P D (2005). Mechanical resilience of degraded soil amended with

organic matter. Soil Science Society of America Journal 69, 864 -871.

titration method. Soil Science 37, 29-38.

St. Augustine, Trinidad, West Indies.

Society of American Journal 73: 226 – 232.

determining soil organic matter and a proposed modification of the chromic acid

tropical soils under intense rainfall. PhD Thesis, The University of the West Indies,

splash detachment and aggregate breakdown under intense rainfall. Soil Science

Erosion is a basic problem found in the entire mountainous regions around the globe. Within the whole alpine area of Europe, thousands of hectares are affected every year, e.g. by construction of ski runs, ski lifts, tourists infrastructure and roads (CIPRA 1998). Besides, natural erosion causes increasingly more problems. According to estimates, 5,000 hectares have to be restored yearly following interventions in high altitudes, more than 50,000 hectares of insufficiently restored areas would need imperative improvement.

High altitudes as the most sensible part of the Alps can be defined as areas within the prealpine and alpine belt i.e. areas above 1,600 msm in the Eastern Alps and areas above 1,800 msm in the Central Alps (Krautzer et al. 2006). Every disturbance in such alpine ecosystems leads to interference that requires different technical and ecological measurements. For lack of plant material in most cases, seed mixtures containing grasses and clover are normally used to establish vegetation again. Restoration of damaged areas in high altitudes is much too often done with an inadequate combination of technical and biological measurements. Cheap application techniques and cheap seed mixtures from species that are not adapted for high altitudes are state of the art. The resulting ecological and economical damage is considerable: soil erosion, extreme surface runoff, degradation of the vegetation, frequent reseeding, constant fertilising, flora falsification, expensive maintenance (Greif 1985, Bittermann 1993). Due to this situation, especially the economically important winter and summer tourism got a very negative image.

The research project "Seed Propagation of Indigenous Species and their Use for Restoration of Eroded Areas in the Alps" (FAIR CT98-4024, short title "Alperos"), supported by the EU, was dealing with the thematic to restore damaged areas using a combination of improved application techniques combined with seed mixtures of indigenous species. The goal of this project was to create a new state of the art in ecological restoration of damaged areas in high altitudes of the Alps. Results obtained during the four years 1999 to 2002 at 8 different locations in altitudes between 1,200 and 2,300 metres clearly showed multiple positive effects if indigenous sub-alpine and alpine species are used for restoration. Up to 20 %

Soil Erosion and Surface Runoff on Slopes in Mountain Environment

Table 1. Soil parameters of site "Hochwurzen"

**2.2 Description of the erosion facility** 

losses during single raining events was not available.

**2.3 Description of the trials** 

(Naschberger & Köck 1983).

last third of May.

Depending on Application Technique and Seed Mixture – A Case-Study 195

K; a favourable base saturation of Ca and Mg and low K saturation. The soil contained a

The average yearly temperature of the site lies at 3.5° centigrade, precipitation at about 1200 mm per year. A meteorological station was installed about 60 m faraway from the experimental plots. Rainfall was measured every 10 seconds and an hourly average was calculated and stored on the data logger. On site Hochwurzen, snow melt ended during the

In order to measure the effects of different techniques on erosion, a mobile erosion facility with three chambers was set up. Figure 1 shows a sketch of the erosion facility. The surface runoff and soil losses from 3 different plots (40 m² each) were collected at the bottom of the plots and passed through a tube to 3 deposit containers for heavy soil components. Water, containing dissolved soil components ran to tip pans of 0.5 and 2 litres (working in dependence on the amount of water) for each plot. The tip pans were connected to a data logger. A bypass was collecting samples automatically. Together with the data of the climatic station, the relation between precipitation and surface runoff was worked out. Measuring the heavy soil components and the dissolved components in the sample container, soil losses were calculated too. For this was very time consuming, soil losses were measured only three times a year for each trial. Therefore, detailed information about soil

In general, our available equipment restricted us to three chambers per year. Therefore, no replications and no statistic evaluation of the results were possible. To make our results more precise, we tried to repeat some techniques (with minor modifications). In order to guarantee comparable conditions, vegetation was killed in autumn using 4 l ha-1 of an herbicide with the active substance Glyphosate. In spring 2000 and 2001, the first 5 cm of soil surface were removed and stored soil surface from a depot near the trial was applied. Table 2 gives a short overall view of the three different trials in 1999, 2000 and 2001-2002. Over all four investigation periods, each chamber was fertilised with 2,000 kg ha-1 of the organic fertiliser "Biosol", one of the most common organic fertiliser for restoration in high altitudes

sufficient content of EDTA extractable Fe, Mn, Cu and Zn (BMLFUW 2006).

higher vegetation cover and thus better protection against erosion three years after sowing, no need for further fertilisation and maintenance on most sites and a much higher percentage of sustainable species are only some of the essential advantages (Krautzer et al. 2010). However, the most risky period where erosion processes can cause considerable damage are the weeks after sowing. Especially indigenous species are germinating and growing very slow. Depending on altitude, vegetation needs 8 to 12 weeks to reach a vegetation cover that is able to reduce erosion to an acceptable degree (Stocking & Elwell 1976, Mosimann 1984). During this period, the vegetation technique has a substantial influence on erosion processes. During the last years, essential work has been done to create simulations and predicting models for soil erosion by water (Morgan et al. 1991, Renard et al. 1997, Klik et al. 1998). Important investigations have been made in order to get knowledge about the influence of different soils and vegetation on erosion and surface runoff in high altitudes (Czell 1972, Schaffhauser 1982, Bunza 1989, Markart et al. 1997). But up to now only little data is available, describing the relations between precipitation, surface runoff and soil erosion during the period after restoration of alpine locations, what is strongly influenced by the chosen application technique (Florineth 2000). On the other hand, restoration companies assure that cheap application methods like normal hand sowing combined with cover crops or plain hydroseeding can be used in most cases (Neuschmid 1996).Up to now we lack on data clearly stating the effects of restoration with different application techniques and seed material on erosion processes on slopes in high altitudes. In the course of the EC project "Alperos", the Agricultural Research and Education Centre Raumberg-Gumpenstein tried to acquire special information about the effects of different common and improved application techniques on surface runoff and soil losses as a basis for further recommendations or stipulations. A special erosion facility was built up in order to measure erosion in dependency on different application techniques after restoration in

high altitudes. Three different trials were carried out in order to answer the following main questions: Water flow and soil losses depending on precipitation, influence of seed mixtures on soil erosion, effect of cover grass and cover crop in comparison to hydroseeding and additional protection of soil surface.

#### **2. Material and methods**

#### **2.1 Site conditions**

The trial were carried out at the location Hochwurzen (1,830 m), a part of the famous skiing centre of Schladming, Austria (13.64° E, 47.36° N). The erosion facility with the plots were set up directly on a ski run with an average inclination of 38 % and an exposition of southeast (SE). The parent rock is Gneis, soil type Leptosol. The soil depth was measured with an average of 16 cm, the water regime can be described as fresh. The climax plant community around the experimental trial on the location Hochwurzen is the Larici-Piceetum; the antropogenic vegetation belongs to the Sieversio-Nardetum strictae. The soils are acid dystric cambisols and leptosols in the Al buffer range (Nestroy et al. 2000).

The classification and descriptions of the soil conditions were done according to the official Austrian guidelines for fertilization of grassland (BMLFUW 2006). The chemical soil conditions of the machine graded site were characterised by a slightly acidic soil pH (carbonate buffer range); relative high humus content (dry combustion) and a relative small C/N ratio (Table 1). The chemical analyses showed a low value of Calcium-Acetat-Lactat (CAL)-extract soluble P; a sufficient amount of Calcium-Acetat-Lactat (CAL)-extract soluble K; a favourable base saturation of Ca and Mg and low K saturation. The soil contained a sufficient content of EDTA extractable Fe, Mn, Cu and Zn (BMLFUW 2006).


Table 1. Soil parameters of site "Hochwurzen"

194 Soil Erosion Studies

higher vegetation cover and thus better protection against erosion three years after sowing, no need for further fertilisation and maintenance on most sites and a much higher percentage of sustainable species are only some of the essential advantages (Krautzer et al. 2010). However, the most risky period where erosion processes can cause considerable damage are the weeks after sowing. Especially indigenous species are germinating and growing very slow. Depending on altitude, vegetation needs 8 to 12 weeks to reach a vegetation cover that is able to reduce erosion to an acceptable degree (Stocking & Elwell 1976, Mosimann 1984). During this period, the vegetation technique has a substantial influence on erosion processes. During the last years, essential work has been done to create simulations and predicting models for soil erosion by water (Morgan et al. 1991, Renard et al. 1997, Klik et al. 1998). Important investigations have been made in order to get knowledge about the influence of different soils and vegetation on erosion and surface runoff in high altitudes (Czell 1972, Schaffhauser 1982, Bunza 1989, Markart et al. 1997). But up to now only little data is available, describing the relations between precipitation, surface runoff and soil erosion during the period after restoration of alpine locations, what is strongly influenced by the chosen application technique (Florineth 2000). On the other hand, restoration companies assure that cheap application methods like normal hand sowing combined with cover crops or plain hydroseeding can be used in most cases (Neuschmid 1996).Up to now we lack on data clearly stating the effects of restoration with different application techniques and seed material on erosion processes on slopes in high altitudes. In the course of the EC project "Alperos", the Agricultural Research and Education Centre Raumberg-Gumpenstein tried to acquire special information about the effects of different common and improved application techniques on surface runoff and soil losses as a basis for further recommendations or stipulations. A special erosion facility was built up in order to measure erosion in dependency on different application techniques after restoration in high altitudes. Three different trials were carried out in order to answer the following main questions: Water flow and soil losses depending on precipitation, influence of seed mixtures on soil erosion, effect of cover grass and cover crop in comparison to hydroseeding and

The trial were carried out at the location Hochwurzen (1,830 m), a part of the famous skiing centre of Schladming, Austria (13.64° E, 47.36° N). The erosion facility with the plots were set up directly on a ski run with an average inclination of 38 % and an exposition of southeast (SE). The parent rock is Gneis, soil type Leptosol. The soil depth was measured with an average of 16 cm, the water regime can be described as fresh. The climax plant community around the experimental trial on the location Hochwurzen is the Larici-Piceetum; the antropogenic vegetation belongs to the Sieversio-Nardetum strictae. The soils

The classification and descriptions of the soil conditions were done according to the official Austrian guidelines for fertilization of grassland (BMLFUW 2006). The chemical soil conditions of the machine graded site were characterised by a slightly acidic soil pH (carbonate buffer range); relative high humus content (dry combustion) and a relative small C/N ratio (Table 1). The chemical analyses showed a low value of Calcium-Acetat-Lactat (CAL)-extract soluble P; a sufficient amount of Calcium-Acetat-Lactat (CAL)-extract soluble

are acid dystric cambisols and leptosols in the Al buffer range (Nestroy et al. 2000).

additional protection of soil surface.

**2. Material and methods** 

**2.1 Site conditions** 

The average yearly temperature of the site lies at 3.5° centigrade, precipitation at about 1200 mm per year. A meteorological station was installed about 60 m faraway from the experimental plots. Rainfall was measured every 10 seconds and an hourly average was calculated and stored on the data logger. On site Hochwurzen, snow melt ended during the last third of May.
