**2.3 Description of the trials**

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 (Naschberger & Köck 1983).

Soil Erosion and Surface Runoff on Slopes in Mountain Environment

Photo 1. Tip pans of 0.5 and 2 litres of the erosion facility "Hochwurzen"

Photo 2. The collecting tube at the bottom of the plots

Depending on Application Technique and Seed Mixture – A Case-Study 197

Fig. 1. Sketch of erosion facility "Hochwurzen"

Fig. 1. Sketch of erosion facility "Hochwurzen"

Photo 1. Tip pans of 0.5 and 2 litres of the erosion facility "Hochwurzen"

Photo 2. The collecting tube at the bottom of the plots

Soil Erosion and Surface Runoff on Slopes in Mountain Environment

2000, a precipitation of 810 mm was registered by our climatic station.

Photo 3. The setup of the three chambers of the trial

chambers we used organic fertiliser "Biosol" (200 g m-

chamber 3, again the straw net "Greenfield S 100" (350 g m-

hydroseeding contained cellulose (80 g m-

From 2000 to 2001, a third trial was set up in order to assess the efficiency of an additional protection of soil surface (chamber 3) in comparison to the common used techniques hand sowing plus cover crop oat (70 kg ha-1, chamber 1) and hydroseeding (chamber 2). The

surface. The first observation period lasted from 27-06-2001 to 11-10-2001. We decided to run this trial also for a second investigation period from 23-05-2002 to 28-08-2002 in order to

²) and gluten ("Curasol", 15 g m-

²) and indigenous seeds (15 g m-²). On

²) was applied on the soil

²). For all

diameter; g m-

Depending on Application Technique and Seed Mixture – A Case-Study 199

techniques are often used in alpine areas, especially on small scale restoration sites. The trial was assessed from 21-06-2000 to 25-10-2000. For this comparison, 15 g m-² of the indigenous seed mixture were used for all three plots. On chamber 2, *Lolium perenne* (variety "Guru") with an amount of 5 % was added as nursery grass to the mixture. 70 kg m-² of summer rye (variety "Tyrolean summer-rye") was used as cover crop for chamber 3. This trial should give an answer to the usefulness of nursery grasses or cover crops to prevent restored areas with an inclination of more than 30 % from erosion. Water samples were collected three times (13-07, 21-08, 25-10). During this investigation period, the nutrient losses of P and K by surface runoff were calculated as the product of the volume of water (l m-²) running off the plot and its concentration (mg l-1). Soil texture and nutrient content of the eroded soil material were analysed at the end of the observation period. The humus- and nutrient loss by soil erosion were calculated from the eroded soil material (particles smaller than 2 mm in

²) and its nutrient content (%, mg kg-1). During the investigation period of


Table 2. Overview of the different trials (application techniques) from 1999 to 2002 on the erosion facility

In 1999, a pilot trial with 3 plots was set up in order to compare a seed mixture of commercial lowland species with an indigenous seed mixture of alpine species (Table 3). The commercial seed mixture in chamber 1 contained 11 species of grasses and herbs, bred for the demands of grassland production. In comparison, the indigenous seed mixture contained 16 species of pre-alpine and alpine species, adapted to the harsh site conditions. All three plots were hand sown, using 15 g seeds m- ². Chamber 2, sown with the indigenous seed mixture like chamber 3, was covered by the straw net "Greenfield S 100" (350 g m- ² straw, interweaved with a jute thread). During June, the equipment was calibrated and optimised. The first trial was assessed from 02-08-1999 to 02-09-1999 in order to test the influence of the two different seed mixtures and in addition the effect of covered soil surface on surface runoff and soil losses. During the investigation period of 1999, a precipitation of 350 mm was registered by our climatic station.


Table 3. Composition of commercial and indigenous seed mixture

In 2000, the second trial was set up in order to prove the efficiency of the additional use of nursery grasses and cover crops in comparison to normal hand seed. All described

mat

grass

cellulose, seeds, organic fertilizer)

Table 2. Overview of the different trials (application techniques) from 1999 to 2002 on the

In 1999, a pilot trial with 3 plots was set up in order to compare a seed mixture of commercial lowland species with an indigenous seed mixture of alpine species (Table 3). The commercial seed mixture in chamber 1 contained 11 species of grasses and herbs, bred for the demands of grassland production. In comparison, the indigenous seed mixture contained 16 species of pre-alpine and alpine species, adapted to the harsh site conditions.

seed mixture like chamber 3, was covered by the straw net "Greenfield S 100" (350 g m-

straw, interweaved with a jute thread). During June, the equipment was calibrated and optimised. The first trial was assessed from 02-08-1999 to 02-09-1999 in order to test the influence of the two different seed mixtures and in addition the effect of covered soil surface on surface runoff and soil losses. During the investigation period of 1999, a precipitation of

In 2000, the second trial was set up in order to prove the efficiency of the additional use of nursery grasses and cover crops in comparison to normal hand seed. All described

hand sowing+straw

(indigenous mixture)

hand sowing+cover

(5% *Lolium perenne*)

hydroseed (gluten,

hand sowing (indigenous

hand sowing+cover crop

hydroseed+straw mat

mixture)

(70 kg ha-1 rye)

². Chamber 2, sown with the indigenous

²

Year I II III

<sup>1999</sup>hand sowing

2000 hand sowing

crop

2001- 2002

erosion facility

commercial mixture

hand sowing+cover

All three plots were hand sown, using 15 g seeds m-

350 mm was registered by our climatic station.

Table 3. Composition of commercial and indigenous seed mixture

(70 kg ha-1 oat)

techniques are often used in alpine areas, especially on small scale restoration sites. The trial was assessed from 21-06-2000 to 25-10-2000. For this comparison, 15 g m- ² of the indigenous seed mixture were used for all three plots. On chamber 2, *Lolium perenne* (variety "Guru") with an amount of 5 % was added as nursery grass to the mixture. 70 kg m-² of summer rye (variety "Tyrolean summer-rye") was used as cover crop for chamber 3. This trial should give an answer to the usefulness of nursery grasses or cover crops to prevent restored areas with an inclination of more than 30 % from erosion. Water samples were collected three times (13-07, 21-08, 25-10). During this investigation period, the nutrient losses of P and K by surface runoff were calculated as the product of the volume of water (l m- ²) running off the plot and its concentration (mg l-1). Soil texture and nutrient content of the eroded soil material were analysed at the end of the observation period. The humus- and nutrient loss by soil erosion were calculated from the eroded soil material (particles smaller than 2 mm in diameter; g m- ²) and its nutrient content (%, mg kg-1). During the investigation period of 2000, a precipitation of 810 mm was registered by our climatic station.

Photo 3. The setup of the three chambers of the trial

From 2000 to 2001, a third trial was set up in order to assess the efficiency of an additional protection of soil surface (chamber 3) in comparison to the common used techniques hand sowing plus cover crop oat (70 kg ha-1, chamber 1) and hydroseeding (chamber 2). The hydroseeding contained cellulose (80 g m- ²) and gluten ("Curasol", 15 g m- ²). For all chambers we used organic fertiliser "Biosol" (200 g m- ²) and indigenous seeds (15 g m-²). On chamber 3, again the straw net "Greenfield S 100" (350 g m-²) was applied on the soil surface. The first observation period lasted from 27-06-2001 to 11-10-2001. We decided to run this trial also for a second investigation period from 23-05-2002 to 28-08-2002 in order to

Soil Erosion and Surface Runoff on Slopes in Mountain Environment

Depending on Application Technique and Seed Mixture – A Case-Study 201

Fig. 2. Soil losses and surface runoff depending on precipitation (362 mm), observation

In the last week of June 2000, the second trial started. This year the investigation period lasted for 18 weeks with a precipitation of 810 mm. During the investigation period, 3 heavy raining events took place. The equipment worked without technical problems. This year we wanted to measure the effects of normal hand sowing in comparison to the very common techniques of hand sowing plus cover crop and hand sowing plus nursery grass as typical cover crop, we used rye of the old landrace "Tyrolean summer rye". As nursery grass, we chose *Lolium perenne* of the variety "Guru", a variety with very good winter hardiness. Corresponding to the extended investigation period, total surface runoff and soil losses were higher in comparison to the year before. Surface runoff of normal hand sowing reached 9.6 % of precipitation, 2 % less than the year before (Figure 3). The effect of cover crop and nursery grass was visible. However, surface runoff decreased only to a percentage of 8.9 for nursery grass and 8.6 for cover crop. Soil losses of chamber 1 reached nearby 2.8 t ha-1. Again, a bit lower values were measured for hand sowing plus cover crop (2.68 t ha-1) and the technique using nursery grass (2.37 t ha-1). In a general view, the reduction of surface runoff and soil losses with the help of fast growing but short living components of the seed mixtures was not substantial. The available water samples and the eroded soil material (particles smaller than 2 mm in diameter; g m-²) were analysed in order to get

Differences in nutrient value of single samples were very high. Therefore, no exact interpretation of results was possible. In a general view, nutrient losses were below 0.5 kg ha-1 for P and from 1 to 1.5 kg ha-1 for K, corresponding to the poor nutrient content of the

period from 02-08-99 to 02-09-99

information about nutrient losses.

measure possible differences in surface runoff and soil losses of the described application techniques during the second vegetation period after sowing. The corresponding vegetation cover of the three chambers was measured at the end of June 2002. During the investigation period of 2001, a precipitation of 568 mm, during 2002 a precipitation of 1,066 mm was registered by our climatic station.

Photo 4. The experimental trial after the application of the different techniques
