Land use management and degradation processes
The main land use and management practice is the intensive use of arable land for cereal production (more than 60% of the entire area), characterised by burning of the residue before the successive deep tillage operations and sowing. Rotation is not practiced on a regular basis, as it depends on the global market dynamics year by year (high revenues = no fallow).
Irrigation is limited to seasonal crops as maize and horticulture in flat areas. Another important use of water is domestic. But most important is the use (better described as exploitation or mining) of springs and aquifers of Mount Vulture for bottling mineral water for national and international markets.
Forest resources are mainly intended to protect the aquifer exploited by the mineral water industry and as production area for chestnut. Also part of forest resource (mainly deciduous forest) is used for firewood production under periodic controlled selective cutting.
Economically the arable land (mainly cereal crops) can provide an acceptable incomebut this depends on the global market dynamics and on the availability and amount of (EU) subsidies. The present way of managing the extensive cereals crops appear not sustainable in the area because of the associated intense degradation. Even olive groves, despite the perennial cover of trees, are extremely poorly managed, with bare, fine seedbed-like soil surfaces in late spring, summer and autumn (intense tillage erosion and water erosion, with cases in which olive trees are rooted in 15-20 cm of soil, just above the tephra.
The main problems at watershed scale related to soil degradation and desertification are illustrated by the intense soil erosion process (both diffuse and concentrated in arable land, vineyards and olive orchards), diffuse mass movements and soil slips , river bank erosion, soil erosion by tillage, loss of natural drainage systems, large sediment source areas (soil erosion evidence up to 1cm/year in olive orchards for water and tillage erosion and up to 2 cm/year in steep sloping arable land), and high connectivity between the primary source of sediment and the drainage network. Land levelling for new vineyard plantations and periodic reshaping of arable land affected by frequent shallow mass movements complete the panorama of the processes contributing to degradation.
The historical data of sediment export from the two main rivers bringing water to the Rendina reservoir and data on sedimentation inside the reservoir indicate that erosion is far above sustainable levels. But data do not tell anything about the distribution of eroded spots inside the catchment. Systematic surveys of the catchment, with erosion monitoring along the whole of it and generation of maps of erosion for the whole basin will allow us to understand what is needed to reduce soil degradation and reservoir siltation.
