Alexander Remke

Land degradation in vineyards is a big concern which should be considered by farmers, enterprises and policymakers. Due to intense tillage, the use of herbicides and heavy machinery, vine plantations are registering a decrease in soil fertility and, subsequently, in productivity. Recently, farmers have decided to abandon the vineyards, but any restoration planning is being carried out to recover biodiversity or to reduce soil and water losses. Nowadays, there is no information about environmental changes after the abandonment in terms of possible soil property changes and erosion in Central European vineyards such as in Germany. Therefore, the main aims of this preliminary study were to compare: i) soil properties and soil profiles of one cultivated vineyard and an abandoned one; and, ii) to assess the activation of soil erosion processes using a small portable rainfall simulator. Our results showed that the vineyard registered several differences in soil properties among slope positions and soil profile characteristics due to tillage and trampling effects, showing clear marks of compaction and soil detachment in the lower parts. Also, in this cultivated field, higher means and maxima of soil losses (g m-2) and sediment concentration (g l-1) values than in the abandoned plot were quantified, being the main driving factors the vegetation cover and the inclination. On the other hand, in the abandoned vine plantation, a rapid homogenization of soil profiles and soil properties were found along the hillslope, where a deeper organic horizon was consistently developed above a compacted and rocky horizon, which was generated during the cultivation phase. Due to the high compaction due to the machinery cultivation and the difficulties for the roots to make deep into the soil, the infiltration defaulted and the amount of runoff and runoff coefficient were higher in the abandoned plots than in the cultivated ones.

In vineyards, especially on steep slopes like the Ruwer-Mosel Valley, Germany, soil erosion is a well-known environmental problem. Unfortunately, some enterprises and farmers are not aware of how much soil is being lost and the long-term negative impacts of soil erosion. The non-invasive technique of the stock unearthing method (SUM) can be used for a quick assessment of soil erosion in vineyards. SUM uses the graft union as a reference elevation for soil surface changes since the time of plantation commencement, which is modelled with the help of a geographic information system. A shortcoming of SUM is that the areas between the pair-vine cross sections are not surveyed, hence it is not accurate enough to identify erosion hot-spots. A structure-from-motion (SfM) photogrammetric technique is adopted to complement SUM to fill this data gap. Combining SUM (only measuring the graft unions) and SfM techniques could lead to an improved, easy and low-cost method with a higher accuracy for estimation of soil erosion based on interpolation by projection, and contact and gapless measuring. Thus, the main aim of this paper was to map the current soil surface level and to improve the accuracy of estimation of long-term soil mobilisation rates in vineyards. To achieve this goal, the TEPHOS (TErrestrial PHOtogrammetric Scanner), a static five camera array, was developed on a 20 m² plot located in a steeply sloping vineyard of the Ruwer-Mosel Valley, Trier, Germany. A total soil mobilisation of 0.52 m³ (9.14 Mg ha yr⁻¹) with soil surface level differences in excess of 30 cm in the 40 years since plantation commencement were recorded. Further research is, however, needed to reduce the number of photos used for the point cloud without loss of accuracy. This method can be useful for the observation of the impacts of other factors in vineyards, such as tillage erosion, runoff pathway detection or the trampling effect on soil erosion in vineyards.

The present paper is based on several field investigations (monitoring soil and rill erosion by aerial photography, rainfall simulations with portable rainfall simulators, and manmade rill flooding) in southern Spain. Experiments lead now to a closer understanding of the dynamics and power of different soil erosion processes in a gully catchment area. The test site Freila (Andalusia, Spain) covers an area of 10.01 ha with a rill density of 169 m ha⁻¹, corresponding to a total rill length of 1694 m. Assuming an average rill width of 0.15 m, the total rill surface can be calculated at 250 m² (0.025 ha). Given that, the surface covered by rills makes up only 0.25% of the total test site. Since the rill network drains 1.98 ha, 20% of the total runoff comes from rills. The rills’ sediment erosion was measured and the total soil loss was then calculated for detachment rates between 1685 g m⁻² and 3018 g m⁻². The interrill areas (99.75% of the test site) show values between 29 and 143 g m⁻². This suggests an important role of rill erosion concerning runoff and soil detachment.