Glossary of Terms
At Plant Life, we wanted to offer our visitors valuable, science-based info about growing and feeding the plants they love. So we created GROWOLOGY 101 to help our visitors navigate through some of the terminology commonly used and industry best-practices when it comes to feeding your plants.
Adsorption: The removal of nutrients in solution by attachment to soil particles.
Aggregates: Many soil particles held together in groups (can also be called peds).
Ammonium N (NH4+-N): A water soluble form of nitrogen (N) that is present in some fertilizers. Ammonium N (NH4+-N) can be converted to ammonia gas and lost to the atmosphere if left on the soil surface. Therefore, fertilizers containing NH4+-N should be watered in.
Anions: An atom or molecule that has more electrons than protons and possesses a negative charge. Several nutrients exist in the soil solution as anions (e.g., nitrate [NO3–], phosphate [PO4–], sulfate [SO4–]).
ATP: adenosine triphosphate; a high-energy molecule bound to 3 phosphates. It is the major source of energy for cellular reactions, this energy being released during its conversion to ADP.
- Boron (B): Plants use Boron to make and transport sugars and carbohydrates and is essential for seed and fruit development.
Bulk density: The mass of dry soil per unit bulk volume (e.g., 1.3 g cm-3).
Calcium (Ca): Regulates the movement of the plants other nutrients and also stimulates enzymes, which helps plants produce new growth and fruit.
Cations: An atom or molecule that has more protons than electrons and possesses a positive charge. Many nutrients exist in the soil solution as cations (e.g., calcium [Ca2+], potassium [K+], magnesium [Mg+]).
Chelate: A nutrient existing as a complex molecule containing carbon, hydrogen, and a metallic ion, which has a prolonged period of plant availability.
Complete Fertilizer: Fertilizer blends classified as a complete fertilizer must contain nitrogen (N), phosphorus (P), and potassium (K). For example, 8-2-12 would be considered a complete fertilizer. Complete fertilizers may also contain other nutrients; however the presence of additional nutrients is not a requirement.
Copper (Cu): Contributes to plant’s seed production and formation, chlorophyll formation and helps with proper enzyme activity. It also increases plant sugar content, intensifies plant color and improves flavor in fruit and vegetables.
Desorption: The detachment of nutrients from soil surface, putting the nutrient into soil solution.
Dissolution: When a nutrient in solid form dissolves into a liquid, dispersing the nutrient throughout the solution.
Fertilizer Blend: Most fertilizers are sold as blends, where several fertilizer materials are mixed together to achieve a specific fertilizer grade. The materials used to create the fertilizer blend are listed on the fertilizer label. Usually this information is identified on the fertilizer label by the words “derived from.”
Fertilizer Grade: The fertilizer grade is the percent (by weight) of nutrients in the fertilizer. For example, a 10-5-5 fertilizer has 10% N, 5% P2O5, and 5% K2O. In a 50 lb bag of 10-5-5 fertilizer, there are 5 lbs N, 2.5 lbs P2O5, and 2.5 lbs K2O.
Fertilizer Ratio: The fertilizer ratio is the proportion of nutrients among the grade. For example, a 10-5-5 fertilizer has a ratio of 2-1-1, or 2 parts N, 1 part P2O5 and 1 part K2O.
Humate (Humic Substances [HS]): An organic component of soil, formed by the decomposition of leaves and other plant material by soil microorganisms. HS have positive effects on plant physiology by improving soil structure and fertility and by influencing nutrient uptake and root architecture.
Inorganic Fertilizers: Inorganic fertilizers are materials that are mined or synthesized from non-living materials. Examples of inorganic fertilizers include ammonium nitrate, concentrated superphosphate, and potassium chloride. Most inorganic fertilizers are considered quick-release or water soluble, unless these products have been altered.
Iron (Fe): Synthesizes chlorophyll and assists in energy transfer within the plant.
Leaching: The downward movement of soil solution through the soil profile.
Macronutrient: A chemical element that is required for plant growth in large amounts. The plant macronutrients include carbon (C), hydrogen (H), oxygen (O), N, P, K, calcium (Ca), magnesium (Mg), and sulfur (S). Plants typically obtain C, H, and O from the air and water and the other macronutrients from the soil solids.
Magnesium (Mg): Helps plant process sunlight (photosynthesis), contributes to the production of ATP, helps carry Phosphorus, the synthesis of sugar and serves as an enzyme activator.
Manganese (Mg): Functions primarily as part of enzyme systems in plants. It plays a direct role in photosynthesis. Manganese accelerates germination and maturity while increasing the availability of phosphorus and calcium.
Micropores: Small soil pores with a diameter of < 0.1 mm.
Micronutrients: A chemical element that is required for plant growth in small amounts. The plant micronutrients include boron (B), chlorine (Cl), cobalt (Co), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo) and zinc (Zn).
Mineralization: The transformation of nutrients from an organic form to an inorganic form, which is plant available. Examples are the transformation of N in plant residues or organic soil into plant available N (resulting in ammonium); also the transformation of organic P to plant available P (resulting in soluble orthophosphate).
Molybdenum (Mo): Crucial for nitrogen fixing and nitrogen reduction. Adequate Molybdenum minimizes the presence of nitrites and nitrates in plant tissues.
Mycorrhiza: Mycorrhizal fungi populate the area around a plant’s roots and form very thin filaments, adding to the length and efficiency of a plant’s roots, allowing them to absorb more nutrients from the soil, improve plant growth and yield and reduce transplant shock.
Nitrogen (N): Nitrogen is primarily responsible for vegetative growth and yield. N helps plants make the proteins they need to produce new tissues. It is also a component of amino acids, the building block for protein in the plant and chlorophyll, needed for photosynthesis.
Nitrate N (NO3–-N): A water soluble form of N that is present in some fertilizers. If not managed properly, this form of N can be a concern for water quality.
Nitrification: The conversion of NH4+-N to NO3–-N by soil microbes.
Organic Fertilizers: Organic fertilizers are materials that are derived from living materials. Examples of organic fertilizers include animal manures, composted materials, and plant residues. Organic fertilizers are usually considered to be “slow-release” fertilizers because many of the nutrients must be broken down by soil microbes before they become available for plant uptake.
pH: a measure of acidity and alkalinity of a solution that is a number on a scale, on which a value of 7 represents neutrality. Lower than 7 indicates increasing acidity and higher than 7 indicates increasing alkalinity.
Phosphorous (P): Critical in root development, crop maturity (buds and flowers) and seed production. Also, a major component of ATP.
Pore space: The portion of soil occupied by gas or liquid.
Potassium (K): Potassium improves overall vigor of the plant. It helps plants make carbohydrates and provides disease resistance.
Precipitation (chemical): When a nutrient that is dissolved in solution forms into a solid. Precipitation occurs when the amount of a nutrient in the soil solution reaches a concentration with other constituents in the soil solution, forcing the formation of a solid, and removing that nutrient from both the soil solution and plant availability.
Runoff: The portion of rainfall or irrigation that exceeds the soil infiltration capacity and flows over or just below the soil surface.
Secondary Plant Nutrients: This term refers to plant nutrients other than N, P, and K, which are required by plants for optimum growth. These nutrients include Ca, Mg, S, Mn, B, Fe, Zn, Cu, Mo, and Cl. Some fertilizer materials will contain one or more of these secondary plant nutrients, which will be listed on the fertilizer label.
Slow-release Fertilizer: Fertilizers that will release nutrients gradually with time. Slow-release fertilizers can be inorganic or organic. Examples of inorganic slow-release fertilizers are sulfur-coated urea and Nitroform. Organic fertilizers contain slow-release nutrients, but, not all nutrients in organic fertilizers are slow-release. Research has shown that organic fertilizers can also contain water-soluble/quick-release nutrients.
Soil fertility: The ability of soil to supply essential nutrients to meet plant requirements.
Soil solution: The water phase of soil and its solutes/nutrients. The soil solution can be taken up by plant roots within a certain range of wetness (field capacity) or dryness (permanent wilting point).
Soil structure: The physical arrangement of soil particles into soil aggregates. Soil structure is described by the shape of the soil aggregates and how they form in the soil profile (e.g., platy, columnar, granular, blocky, prismatic, or massive).
Soil texture: The relative proportion of sand, silt, and clay particles in the soil. Note that soil texture does not include organic matter.
Sulfur (S): Sulfur is essential for maximum crop yield and quality. It is a major component in the synthesis of protein in plants. It also helps the plant’s resistance to disease, aids in growth, and in seed formation.
Water Soluble: This term indicates that the fertilizer material will dissolve in water. Once dissolved, nutrients in the fertilizer are available for uptake by plant roots. The terms water soluble and quick-release are synonymous.
Zinc (Zn): Zinc is involved in the production of chlorophyll, protein, and various enzymes involved in metabolic reactions for proper growth. It influences the rate of seed and stalk maturation and helps plants withstand lower temperatures.