# Fertilization > Part of: [Irrigation](/irrigation.md) · Provider: [DutchGreenhouses](/) Fertilization builds the nutrient solution the crop actually receives, from concentrated stock held in two separate tanks. Calcium salts sit apart from phosphates and sulphates because at hundredfold concentration they would precipitate as calcium phosphate and gypsum; in the diluted solution that reaches the dripper they coexist without trouble. ## Facts | Property | Value | |---|---| | Stock solution concentration factor | 100 × | | Delivered EC ceiling for hundredfold stock | 2 mS/cm | | Maximum free acid in the iron-chelate tank | 0.5 mmol/L | | Stock tank pH ceiling | 5 pH | | Sulphate requirement | 0.5–1 mmol/L | Irrigation # Fertilization. The crop eats through the dripper. ## The crop eats through the dripper In a modern greenhouse the plant is fed through the irrigation water, not the soil, so fertilisation and irrigation are effectively one system. Concentrated nutrient stocks are held in separate A and B tanks — kept apart because calcium from one and sulphates or phosphates from the other would react and precipitate if mixed at full strength — and are dosed into the irrigation flow in precise proportions on every irrigation turn. The result is that each dripper delivers not just water but a complete, dissolved meal tuned to the crop. The recipe itself is built from the major nutrients — nitrogen, potassium, calcium, phosphorus, magnesium — together with the trace elements such as iron, manganese and boron that a crop needs in tiny but essential amounts. The dosing system continuously measures the electrical conductivity (EC) and pH of the mixed solution and corrects on the fly: EC tells it how concentrated the feed is, pH keeps the nutrients in the chemical form the roots can actually absorb. Hold those two values steady and the crop gets exactly what the grower intends, drip after drip. Crucially, the balance is not fixed — it shifts with the growth stage. Young, vegetative plants want a nitrogen-led recipe to build leaf and structure; at flowering and fruit set the emphasis moves toward potassium and calcium to support fruit quality and prevent disorders; in full production the feed is balanced to sustain a heavy, continuous crop load. In recirculating systems the calculation is more subtle still, because the returning drain water already carries residual nutrients that must be measured and accounted for before fresh fertiliser is added, so nothing is wasted and nothing accumulates to toxic levels. Getting fertilisation right is one of the highest-leverage decisions in the whole operation: it drives yield, quality and shelf life directly, and it is where a skilled grower earns their keep. We engineer the dosing installation — tanks, injectors, measurement and control — around the crop and water source, and through our grower support help build the recipes that make it perform. Get in touch to design fertilisation 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 **Why are there two fertiliser tanks?** Because of solubility, not convention. At hundredfold concentration calcium would precipitate with phosphate and sulphate as calcium phosphate and gypsum, and Dutch analyses of blocked emitters find exactly those compounds. In the diluted solution reaching the plant the same salts coexist without difficulty, so the split exists only because of the concentration factor. **Which fertilisers go in which tank?** Calcium nitrate and the iron chelate go in the A tank; potassium sulphate, phosphates and the remaining micronutrients go in the B tank. Potassium nitrate, magnesium nitrate, ammonium nitrate and nitric acid can go in either, and are placed to balance the load so both tanks empty together. **Why is nitric acid used rather than phosphoric acid?** Both correct pH, but phosphoric acid contributes proportionally far more phosphorus than nitric acid contributes nitrogen. Under recirculation a sustained phosphorus surplus accumulates in the root environment and can reach toxic levels, so the acid choice is a consequence of running a closed loop rather than an open one. **Can the concentration factor be raised above a hundredfold?** Only within limits. Hundredfold stock works up to roughly EC 2.0 in the delivered solution; above that the concentrate becomes supersaturated and salts drop out, which changes the composition as well as blocking equipment. The concentration factor is an engineering consequence of the target EC, not a free parameter. ## Related [Irrigation](/irrigation.md) · [Pre-treatment](/irrigation/pre-treatment.md) · [Dosing](/irrigation/dosing.md) · [Fertigation](/glossary/fertigation.md) · [Nutrient Solution](/glossary/nutrient-solution.md) · [EC (Electrical Conductivity)](/glossary/ec-electrical-conductivity.md) · [pH](/glossary/ph.md)