Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
2025
Abstract
The new European organic regulation claims that cultivation must occur directly in soil in greenhouses. Cultivation practices in accordance with organic principles require the use of sustainable growing media and the addition of compost for soil improvement, preferably local resources. Soil improvement aims to achieve good soil health, including biological soil activity, nutrient availability, and favourable physical properties. However, only a few studies have been conducted on biological soil health in greenhouses. Biological soil activity was monitored in a greenhouse cucumber experiment on organic soil enriched with biochar and supplemented with local 1) compost, 2) solid digestate from biogas production, or 3) imported peat. The effects of silage mulching were also tested. Biological activity was measured in the soil using different indicators, while plant growth was monitored above soil. Results indicated that the mixture with compost contained more organic matter than other mixtures. Biological activity in the compost mixture was lower and started later than in the other mixtures. Silage mulch increased biological activity in all mixtures. Respiration rates and fungi content classified all three mixtures as stable growing media. At the start of the experiment, nitrogen content and pH levels in all three mixtures were similar. The peat mixture required the most mineral amendments, phosphorous content was highest in solid digestate and lowest in peat. Plant nutrient turnover to the plants was appropriate, although a lack of micronutrients was observed. Yields performed well. Our results show that biological activity in compost starts later in compost compared to the other mixtures. Anyhow compost is considered a key component of soil health. Fungi:bacteria balance was similar and comparable to measurements in Norwegian organically managed soil. Indicators were useful at farm level; they could be diversified further. Local compost and digestate performed as good as peat.
Abstract
No abstract has been registered
Authors
Michel VerheulAbstract
No abstract has been registered
Authors
Michel VerheulAbstract
No abstract has been registered
Abstract
No abstract has been registered
Authors
Michel VerheulAbstract
No abstract has been registered
Authors
Michel VerheulAbstract
To document effects of High-Pressure-Sodium (HPS) and Light-Emitting Diodes (LED) lamps, six different cucumber cultivars (‘DeeRect’, ‘HiLight’, ‘Imea’, ‘Keirin’, ‘Shakira’ and ‘Topvision’) were grown hydroponically in a semi-commercial greenhouse compartment using standard HPS or LED supplemental top-light from December to March. A PPFD of 240 µmol m-2s-1, 20h a day, was used for both lamp types. In addition, plants were grown with or without LED inter-lighting (45 µmol m-2s-1, 20h a day). Global radiation during the experiment was less than 1.5 MJ m-2day-1. Setpoints for day and night temperatures were 24 and 21 oC respectively. CO2 concentration in the greenhouse was kept at 1100 ppm. Morphological traits (stem length, leaf area, leaf thickness, dry weights), yield (fruit fresh weight and number of fruits) as well as quality parameters were registered. Results show that the use of LED top-light reduced yield considerably compared to HPS top-light, mainly due to a reduction in the number of 1st class fruits harvested. Plants grown using HPS top-light were longer, had more internodes, a higher fruit weight, bigger leaf area and leaf area index (LAI) and ‘thinner’ leaves compared to plants grown using LED top-light. Light use efficiency (g FW mol PAR-1) was highest using HPS or a combination of HPS and LED inter-light and lowest using LED combined with LED inter-lighting, especially at the start of the harvesting period. Huge differences in yield reduction between different cultivars were observed. LED top light reduced the yield of ‘DeeRect’ with 35% and of ‘HiLight’ with 5% compared to HPS top light. Little differences in quality traits were observed between cultivars grown under HPS or LED lamps. However, inter lighting increased fruit weight and fruit quality (color, dry matter content, soluble solid content, chlorophyll content, vitamin C content and storage properties). Causes of differences between lamp types and effects on commercial greenhouse cucumber production in Norway are discussed.
Authors
Michel VerheulAbstract
No abstract has been registered
2024
Abstract
No abstract has been registered
Authors
Michel VerheulAbstract
No abstract has been registered