Successful implementation of biofiltration at EARL Le Bihan

At the beginning, only vine tomatoes were grown at EARL Le Bihan in Plouénan. Nowadays,  a wide range of almost 30 specialty tomato varieties of all shapes, sizes and colors (green, yellow, red, black)le-bihan1 is grown at this company. There are two greenhouses with a total area of 2.8 ha. One greenhouse is used for the production of small fruit varieties (cherry tomatoes) and the second one for varieties with larger fruits. As it wasn’t possible to expand the farm, the grower chose to diversify the production and focus on specialty tomatoes that offer higher value.

Due to this wide range of varieties, irrigation and fertilisation management are challenging at EARL le Bihan.  Therefore, the two greenhouses are monitored and managed separately. In each of them, a reference variety is placed on a substrate balance. Usually, the most water demanding variety of each greenhouse is selected as the reference variety. The irrigation of each of the two greenhouses is managed based on the requirements of the “reference variety”. However, this often results of over irrigation for some of the varieties, but so far it is the best way the grower can think of. Furthermore, the grower installed a system (Aqua4D) to reduce the biofilm and Agrobacterium rhizogenes development. The system has been installed last year but the grower needs more time to evaluate its efficiency.

At EARL le Bihan, the only water source is groundwater which is buffered by a  90% is the maximum ratio of the drainage which can be recycled. Indeed, the first drainage coming out of the coco slab is leached, because of its high content in organic matter and salts. Moreover, the ionic accumulation due to the use of groundwater forces the grower to discharge drainage from time to time.The drainage water is disinfected through a dynamic slow sand filter, also referred to as a biofiltration. The drainage will slowlimg_2852y flow through a bed of media on which microorganisms are attached, forming a biofilm. They will degrade the pathogens and establish a microbial balance in the drainage.  This treatment method was selected as it enables efficient bacterial balance in the water and makes the system more resilient as the risk for the quick development of one pathogen species in case of problems is minimised. An additional benefit of this treatment method is the low maintenance that is required compared to other systems as UV.

Have a look at the water scheme of EARL le Bihan


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