The Environmental Impacts of Greenhouse Agriculture in Almería, Spain
If you look at a satellite image of Spain, you will observe a white dot in the South East of the peninsula often referred to as the ‘Orchard of Europe’. The plastic greenhouses making up that white dot supply many European supermarkets with their affordable produce. But how sustainable is this high-yield agricultural system?
The development of intensive agriculture in Almería started in the 1960s, when the government allocated plots of land to a young population that had migrated from other parts of the country. At the time, this decision was made to create jobs and to grow the economy. Today, these farms take up 320 km2 and collectively represent the most extensive greenhouse area in the world - accounting for around 38% of Spain’s horticultural production and employing tens of thousands.1 But their high production rates - with productivity 30 times that of the average European farm - bring with them pressures on the environment that threaten their future and that of the surrounding ecosystems.2
High-yield farming uses less land
Some experts claim that high-yield agriculture allows farmers to grow more food on less land, and therefore leads to a decrease in the conversion of natural to agricultural landscapes.3 Since deforestation and habitat destruction are shown to be among the main causes for the substantial environmental impacts of food production, learning to sustainably grow more food with less land is a real priority in the coming decades.4,5
Our cuisines and demands have adapted to seek produce that often doesn’t grow in our proximity. In fact, it was the demand from Northern European countries that prompted and maintained the expansion of the greenhouses in Almería. To this day, 80% of the grown products under the greenhouses are exported to northern Europe; mainly Germany, France, the U.K and The Netherlands.6,7 Thankfully, the vast majority of the produce is transported by road, which greatly minimizes their environmental impact.5 But while these greenhouses support the demand for affordable Mediterranean and subtropical produce year-round in an efficient way, they come with their own set of issues.
Greenhouses create a sea of plastic
Across Spain, the area covered by greenhouses is commonly referred to as “el mar de plástico”, or the “plastic sea”.8 Each year, the greenhouse complex of Almería, bordering the Sierra Alhamilla national park to the north and the Mediterranean Sea to the south, generates around 33,500 tonnes of plastic waste.9 Some of this waste is illegally dumped; in the past, videos shared by NGOs, journalists or social media expose shocking images of surrounding landscapes heavily littered with the materials used for the greenhouses covers, bags or cans of fertilizers and produce packaging materials.9,10,11 While recycling companies have been emerging near to the greenhouses in recent years to help deals with this problem, the collection of inorganic waste from all the small farms is complex and expensive.12 With inadequate waste management systems in place, the surrounding environment has paid a price. Unmanaged agri-plastics have been found blocking riverbeds, ending up at sea or being ingested by birds or other land species.13 A few years ago, a sperm whale washed up dead on the Almería coast and was found to have 17kg of plastic in its digestive system, largely coming from the plastic sheetings of the greenhouses.14
Greenhouse horticulture in Almería is located near protected natural areas. These reserves, many of which are part of the EU’s nature network Natura 2000, contain priority habitats and species (e.g migratory birds) and provide many ecosystem services like erosion control and groundwater recharge. The expansion of greenhouses and urban areas in the past decades has posed a threat to these protected natural areas.15
Pressure on groundwater sources
Paradoxically, while Almería represents one of Europe’s largest areas of intensive agriculture, it is found in one of the driest regions of the continent.16 The south east of Almería usually gets around 200mm of rain per year - for scale, even the comparably warm and dry city of Barcelona gets around 614mm per year.17 In the past, agriculture was adapted to this dry climate. Farmers specialized on the Mediterranean triad - olives, grapes and wheat - which require little water and easily survive droughts. However, the greenhouses today specialize in non-native crops like tomatoes and watermelons, which require a higher water demand.18
The discovery of aquifers (groundwater stores) in the 1940s was one of the factors that set in motion the development of the agricultural sector in Almería. These newfound groundwater stores allowed for quick access to a seemingly abundant supply of water needed to grow crops on a large scale. But while it was an economic blessing for the sector and vastly improved living conditions, the region quickly started depending on groundwater as its main water source - now constituting more than 80% of the water used for Almería’s agriculture.15 Since aquifers are replenished with rainfall, the low precipitation rates in Almería mean aquifers are being exploited far quicker than they can naturally refill. As well as being depleted, aquifers are also being degraded. A dramatic increase in both the salinity of groundwater, caused by the intrusion of seawater (a process common in overexploited coastal aquifers), and the nitrate concentration, originating from fertilizer runoff, are raising concerns for local biodiversity and drinkable water quality.19, 21
Sustainable progress in Almerian horticulture
While the unbounded sprawl of greenhouses can seem like the opposite of what some of us imagine sustainable food production to look like, the ambition to make greenhouse agriculture in Almería more efficient, circular and durable is ongoing.17 A study looking at the sustainability of greenhouse production systems through the lens of the Sustainable Development Goals found that through the use of sustainable practices and technology, greenhouse farming can minimize the use of land, energy and water needed to produce very high yields.21 An additional study found that Spanish greenhouses require 22 times less an energy than Dutch greenhouses, by harnessing the light and heat of the sun instead of relying on artificial sources.22 Additionally, the ability to produce such large amounts of food all year round with few inputs allows it to be sold at affordable prices, bringing a varied diet and lower-impact plant-based ingredients to a wider public.
Most farms in south east Spain are also progressing to make use of technologies and practices that allow them to become more sustainable - such as using biological pest control (insects) to replace insecticides, managing practices to reduce nitrate leaching, and incorporating water saving drip irrigation methods.17, 23 Other innovations that are being set in motion include using desalinated water instead of groundwater, collecting rainfall from greenhouse roofs, expanding the area cultivated in soil-free hydroponic systems, automating irrigation to optimise the volume of water used to the need of each plant and increasing the share of organic crops.10, 19, 24
Finally, as a result of the reflectivity of the white greenhouse tops, the agricultural landscape in Almería has, as opposed to the rest of the region, experienced a cooling trend of 0.8 °C compared to its surroundings. By reflecting solar radiation, the surface of the Almería agricultural landscape can partially decrease the greenhouse effect, indirectly offsetting the carbon footprint of the greenhouses by up to 45%.25
A greener future
It is no question that we will have to significantly boost the efficiency of our food production in the coming years. Innovative and efficient food production systems will be necessary to fill the gap between production and consumption without significantly expanding agricultural land. Despite its shortcomings, the Almerian greenhouse horticultural system, with a productivity 30 times higher than the EU average, provides a possible model (for better or worse) for how this can be done.26 Having gone from deserted shrubland to the European Union’s major vegetable and fruit exporter in just a few decades, this is a success story for many of the region’s residents and agronomy experts around the globe.17, 26 Still, the pressures of our current food system demand for an ever-increasing volume and diversity of produce, which the soils and water reservoirs of Andalucia weren’t made for. To be a true example of sustainable intensification, it is important that farmers and policymakers continue to address and minimize the impact of intensive horticulture on the surrounding environment.
Do you think the benefits of greenhouses outweign their cost?