In general, the optimal pH range for growing vegetables hydroponically is 5.0 to 7.0. For example, a value of 7 is 10 times higher than 6 and 100 times higher than 5. This means that small changes in values are large changes in pH. The scale is logarithmic, and each unit represents a 10-fold change. It is measured using a 0- to 14-point scale where 0 is the most acidic, 7 is neutral, and 14 is the most alkaline. pH is a measure of the relative acidity or hydrogen ion concentration and it plays an important role in plant nutrient availability. In hydroponics, we are primarily concerned with the pH of the water used to make up nutrient solutions and irrigate plants. It is impossible to discuss plant nutrition without considering pH. Redox changes, photosynthesis, respirationĬomponent of some enzymes, biological nitrogen fixation, nitrogen metabolism Nutrient (chemical symbol)Īpproximate content of plant (% dry weight)Ĭomponent of amino acids, proteins, coenzymes, nucleic acidsĬomponent of sulfur amino acids, proteins, coenzyme AĪTP, NADP intermediates of metabolism, membrane phospholipids, nucleic acidsĭihydrogen phosphate (H 2PO 4 -), Hydrogen phosphate (HPO 4 2-)Įnzyme activation, turgor, osmotic regulationĮnzyme activation, signal transduction, cell structureĮnzyme activation, component of chlorophyllĮnzyme activation, essential for water splitting Approximate content in plants, roles in plants, and source available to plants of essential plant nutrients. Sources of nutrients available to plants are listed in Table 1. The rest of the nutrients are from soil or in the case of hydroponics from nutrient solutions or aggregate media. Plants get carbon, hydrogen, and oxygen from air and water. Table 1 shows the approximate plant content of essential nutrients. Macronutrients are required in higher amounts than micronutrients. The difference between macro- and micronutrients is the amount required by plants. Micronutrients include iron, manganese, zinc, boron, molybdenum, chlorine, copper, and nickel. Macronutrients include carbon, hydrogen, oxygen, nitrogen, phosphorus, potassium, sulfur, calcium, and magnesium. Macronutrients and micronutrients are both essential for plant growth and development. Table 1 lists the plant roles of essential nutrients.Įssential nutrients can be broadly categorized as macronutrients and micronutrients. Magnesium is the center of the chlorophyll molecule. It also reflects green wavelengths and is the reason most plants are green.
Chlorophyll is a pigment used to capture energy from light that is needed in photosynthesis. For example, magnesium is a critical component of chlorophyll.
These nutrients are needed so that processes critical to plant growth and development can occur. Plants cannot properly function without 17 essential nutrients. Here, we are using hydroponics to mean growing plants without soil. With this definition growing plants in soilless media (potting soil) or other types of aggregate media such as sand, gravel, and coconut coil are considered hydroponic systems. Another definition of hydroponic is growing plants without soil. Examples of this type of hydroponic systems includes NFT (nutrient film technique) systems and deep-water float systems where plant roots are set in nutrient solutions. Hydroponic can be defined as growing plants in water containing nutrients.
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