Managing irrigation and fertigation on ornamental plants

At GAEC de Mezavern in Plouénan, the grower presented his 10 ha nursery. Besides the main crop of bamboo, also other ornamental plants are grown like hedge plants, Nandina, Grevilia, Rosemary, Lavatera, Viburnum tinus. Plants are grown in pots, on outdoor container fields or under shelters (bitunnel/ multi span greenhouse). Most species are grown in a mixture of peat and bark but for bamboos, the substrate contains rice hulls as well.

On the farm, a mixture of water sources is used for the irrigation. This mixture consists of groundwater, drainage water collected in the drains under the cultivation areas and the rainwater harvested from the roofs of the shelters. In general, the drainage water has good quality as it contains a high proportion of rainwater (70%) so does not need to be treated. For Nandina species he uses only groundwater as even light debris of the mixed water can affect the plant visual quality.

Irrigation is mainly provided by aspersion (85%). Although, the recent years they increased the area that uses drip irrigation to improve water use efficiency. Nowadays, drip irrigation has not fully implemented at the farm due to the high installation cost but as well due to practical reasons. Drippers can be easily damaged by staff when moving the pots around. Irrigation management is based on the grower’s experience. Above, 2 trained employees are visual inspecting the plants and schedule the irrigation. They don’t use moisture sensors as it is time-consuming and the diversity of the farm does not allow it. There are two irrigation stations at the farm that used to schedule irrigation according to the needs determined by the irrigation managers.

The main source of nutrients is slow-release fertilisers incorporated in the substrate as well as top dressing. Fertigation is only used complementary to address nutrient deficiencies. The irrigation system limits the efficiency of fertigation as big volumes of nutrients are leached and as well it is difficult to control and isolated the application only on the desired area.

Source: FERTINNOWA