# Dosing > Part of: [Irrigation](/irrigation.md) · Provider: [DutchGreenhouses](/) Dosing is the injection of stock solution and acid into irrigation water under continuous EC and pH measurement, then delivery to each valve section. Dutch practice uses positive-displacement pumps under feedback control, increasingly one injector per fertiliser, so the recipe changes without remaking a premixed stock. ## Facts | Property | Value | |---|---| | Emitter flow coefficient of variation ceiling | 7 % | | Distribution uniformity below which investigation is required | 70 % | | Minimum flushing velocity | 0.3 m/s | | Manufacturing variation for an excellent point-source emitter | 5 % | | Substrate sensors in the controlling valve section | 3 sensors | Irrigation # Dosing. Exactness, delivered per dripper. ## Exactness, delivered per dripper If fertilisation is the recipe, the dosing unit is the kitchen where it is made — the heart of the irrigation room and one of the most important pieces of technology in the whole greenhouse. Its job is to take incoming water and inject the concentrated A and B nutrient stocks and acid into the stream in precisely the right proportions, so that what reaches the crop is mixed to the exact electrical conductivity (EC) and pH the recipe demands. It does this continuously, adjusting on the fly, because the quality of every irrigation depends on getting that mix right. Crucially, the dosing is not one-size-fits-all across the greenhouse. A large facility is divided into valve sections — different crops, different growth stages, different microclimates — and a good dosing installation delivers the appropriate recipe to each section on each irrigation turn. A young crop just planted and a mature crop in full production sitting under the same roof can each receive their own EC, pH and volume, rather than being forced onto a single compromise setting. What elevates modern dosing from a mixing machine to a management tool is measurement and logging. Every irrigation turn is recorded — the volume applied, the EC and pH actually achieved, and the drain percentage that comes back — and that data feeds the loop a grower uses to steer the crop. Drain percentage in particular is a vital signal: it tells the grower whether the plants are receiving too much or too little, and lets them tune irrigation frequency and volume to keep the root zone in balance. Without accurate logging, cultivation is guesswork; with it, it becomes a measurable, improvable process. Reliability matters as much as precision, because the dosing unit sits on the critical path of the entire crop — if it fails or drifts, every plant downstream is affected within hours. DutchGreenhouses® engineers the dosing installation — injectors, measurement, control and redundancy — around the crop, the water source and the recirculation strategy. Get in touch to design the dosing for your greenhouse. From the knowledge base ## Reads you might find interesting ceacultivationbusiness-case ### Grow Like a Pro: Starting Smart, Growing Strong How Grow Like a Pro combines smart farming, CEA technology and local partnerships for eco-friendly, profitable, pesticide-free greenhouse pr Read article education ### The Case for a College Greenhouse Why a college greenhouse belongs in the curriculum: teaching science, craftsmanship, business logic and sustainability, and preparing studen Read article education ### The Case for a High School Greenhouse Why every high school greenhouse matters: how it makes STEM tangible, builds responsibility and teamwork, and helps students discover their Read article education ### Greenhouses in Education: The Case for Schools Greenhouses in education reconnect students to reality — the full case for why every school, high school, college and trade program should h Read article historyconstruction ### The Origins of Greenhouse Horticulture: My Backyard A tour through greenhouse horticulture history: from 19th-century Westland fruit walls to the “City of Glass” and today’s international high Read article company ### DutchGreenhouses Rebranded: A New Corporate Identity Announcing our new corporate identity — a visual style reflecting our dedication to advanced, high-quality greenhouse projects and The Futur Read article ## FAQ **Does a 20 percent pressure variation really give 10 percent flow variation?** Only for one kind of emitter. That figure is arithmetic from an emitter exponent of 0.5, the value for a turbulent orifice. A non-compensating emitter with an exponent of 0.8 gives 15.7 percent flow variation for the same pressure swing, and a fully pressure-compensating emitter gives almost none. It is a derived result, not a standards requirement. **How is irrigation uniformity measured?** Through four distinct measures that are often confused. Emission uniformity describes the design, from manufacturer variation and minimum pressure. Distribution uniformity and statistical uniformity describe the installation as built, from measured flows at a minimum of eighteen points per zone. Christiansen's coefficient comes from sprinkler practice and gives only a broad indication for drip. **Are venturi injectors used in Dutch greenhouses?** Dutch sources describe positive-displacement dosing pumps under EC and pH feedback, increasingly with one injector per fertiliser so the recipe can change without remaking a premixed stock. Venturi injection appears in international material aimed at open field, orchards and low-cost tunnels rather than in high-tech glass. **Why should the dosing unit avoid metal fittings?** Because neutralising bicarbonate with acid releases carbon dioxide and leaves the water aggressive to metal. Published Dutch guidance is that the dosing unit and irrigation lines should preferably carry no metal fittings at all, since the corrosion products end up in the emitters. ## Related [Irrigation](/irrigation.md) · [Fertilization](/irrigation/fertilization.md) · [Hydroponics](/irrigation/hydroponics.md) · [Dosing Unit](/glossary/dosing-unit.md) · [Drip Irrigation](/glossary/drip-irrigation.md) · [EC (Electrical Conductivity)](/glossary/ec-electrical-conductivity.md) · [pH](/glossary/ph.md)