LEDD issues in cropland: Western Andévalo

Editor's note 30 Apr 2012: Text source D111.

Aquifer depletion

Huelva province has the highest concentration of strawberry production in the world. Spain is the biggest producer of strawberries in Europe and of the total production of strawberries in Spain, 95 percent come from Huelva province (AE MARM 2010). A significant issue related to the commercial production of strawberries in the region is the overexploitation of aquifers. In areas near the Doñana natural park this has lead to a fifty percent reduction in water levels in aquifers and natural watercourses (WWF/Adena 2008). Amongst other impacts, the depletion of water resources affects biodiversity in the park and in the region as a whole.

Soil erosion

Orange plantations are particularly susceptible to erosive processes (Cerda et al. 2009). Trees stand on bare soil on undulating slopes, with very little or no undergrowth. During the wet season, runoff of sediment into local drainage systems is a particular issue. Evidence of rill erosion is common and at longer established plantations, gullies can be seen in the depressions in between the planted mounts. Little use is made of natural patterns of relief in the landscape in new plantations. Often, the mount-depression-mount pattern is created parallel to the angle of the slope. With no undergrowth present, runoff and soil movement processes find no resistance and soil is lost through existing and newly created or eroded waterways.

Cerdá et al (2009) have also found that soil erodibility in recent, newly converted and intensive citrus orchards is higher than in any other land use in the western Mediterranean basin.  The Western Andévalo is one of the fastest expanding areas of this type of commercial citrus operation in Spain. High erosion rates and the off-site impacts of sediments are having, and will continue to have, a significant impact on the biophysical and human systems across the region..

Contamination of soil and water

The inappropriate use of fertilizers, herbicides and pesticides can lead to pollution both on and off site (Curfs 2009). Agri-chemicals are frequently used in large scale commercial citrus production in Huleva. The use of nitrogen to improve crop yield is a common practice in citrus production.  However, as a result of a lack of knowledge of the physiological and biochemical basis of the nutrition process, the application of nitrogen fertiliser is indiscriminate and results in nitrate leaching and loss into watercourses (Talon 2004).

The off-site impacts in relation to soil and water contamination are also important considerations. The orange plantations are part of the Guadiana drainage basin. In wet periods, eroded soil (and associated agri-chemicals) enters the Guadiana River. This may contribute to contamination of river sediments and beaches at the mouth of the estuary, where the tourism industry is currently expanding.

Land desertification

The process of converting the landscape into orange plantations in broad terms can be described as follows: Heavy earth moving machinery is used to scrape the soil bare in order to collect boulders, which are put in mounds for collection by lorries. Mechanical diggers are then used to create the parallel mound-depression-mound pattern. The boulders are then used to cover the mounds on which the trees are planted. The LEDD issues that are associated with this process include:

• Loss of biodiversity - citrus orchards are a monoculture and existing vegetation is cleared and removed;
• increased soil erosion by wind and water because of
• compaction by heavy machinery
• the removal of vegetation
• the long periods in which the area is left bare before planting starts

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