Hyacinth bulbs are normally grown in the open field. As a result, fertilizers may leach into surface water. Moreover, the bulbs are susceptible to soil-borne diseases and pests (such as fungi and nematodes). Research by the Horticulture and Flower Bulbs Business Unit of Wageningen University & Research shows that bulbs can also be grown well in plastic trenches.
The Bollencoaster project aims to make bulb cultivation more sustainable. One of its components is research into the use of plastic trenches. These are dug into the field at a depth of 10 to 20 centimeters deep and with a width of about 5 centimeters. In the trench is a drip hose for watering and nutrient application. The top of the trench is closed to prevent diseases, pests, and unwanted water from penetrating. In the trench, the bulbs are planted in a substrate.
When growing hyacinth, this cultivation method has many advantages. It allows targeted watering, for instance, and there is no leaching of water and fertilizers. Moreover, fewer plant protection products are needed. Because of the trench, the bulbs grow in a long row: this facilitates mechanical weed control. As the bulbs do not grow in the soil, fungi, and nematodes cannot attack the crop. So crop rotation does not have to take place (in conventional crops, hyacinths can only grow on the same soil once every six years). As a result, growers do not have to look for a new field every year. And most importantly, the bulbs grow well in the enclosed environment.
There are also drawbacks and concerns. For instance, the soil in the trench must be sufficiently nutritious and clean. This can be achieved by using new substrates, such as coco peat substrates, during each cultivation round. An alternative is to use sand in the field. However, this must first be steamed and possibly provided with biostimulants. Moreover, the grower has to invest in plastic trenches and the drip system, among other things. The top of the trench sometimes appears to open up, allowing rainwater, for instance, to enter the trench. In addition, the soil around the trenches should be prevented from becoming impoverished: it might therefore be wise to grow something else between the hyacinths, such as grass.
The hyacinth research is taking place at Agrifirm-GMN in Voorhout. A study on lilies is taking place on the same field (both crops alternate in spring and autumn). At WUR's research location in Bleiswijk, research is also taking place into the possibility of growing other flower bulbs in this system, such as tulip, gladiolus, and zantedeschia.
Bollencoaster is a four-year research program of the top sector Horticulture & Starting Materials of the Ministry of Agriculture, Nature, and Food Quality. The implementation of this Public-Private Partnership lies with a consortium of seven partners. These are: KAVB, Agrifirm-GMN, Oerlemans Plastics, Rabobank Bollenstreek, Hoogheemraadschap Rijnland, Greenport Duin & Bollenstreek and Wageningen University & Research.
Source: Wageningen University & Research
