Coco Coir and Hydroponic Cultivation Glossary

A Technical Reference for Hydroponic Production in Controlled Environment Agriculture

Aeration

The presence and movement of air within the substrate root zone. Aeration is governed by air filled porosity and pore structure and is essential for oxygen diffusion to roots. Inadequate aeration leads to reduced root respiration, impaired nutrient uptake, and increased susceptibility to root pathogens.

Air Filled Porosity AFP

The percentage of total substrate volume occupied by air after gravitational drainage. Adequate AFP is essential for root respiration and prevention of hypoxic stress.

Alkalinity

The buffering capacity of irrigation water, primarily derived from bicarbonates and carbonates and expressed as ppm CaCO3. High alkalinity resists pH adjustment and must be neutralized for stable nutrient solution formulation.

Assimilation

The metabolic incorporation of absorbed mineral nutrients into plant tissues.

Buffering

The process of treating coco coir with calcium rich solution to displace excess sodium and potassium from cation exchange sites. Proper buffering stabilizes nutrient availability prior to planting.

Bulk Density

The dry mass of substrate per unit volume. Bulk density influences porosity, water retention, and root penetration.

Capillary Action

The movement of water within substrate pore spaces due to adhesion and cohesion forces.

Cation Exchange Capacity (CEC)

The quantity of negatively charged sites within a substrate capable of holding exchangeable cations such as calcium, magnesium, potassium, and ammonium. In coco systems, CEC significantly influences nutrient retention and release dynamics.

Charging

The act of saturating coco substrate with a balanced nutrient solution prior to planting in order to establish stable root zone nutrient ratios.

Chelates

Organic compounds that bind micronutrient ions and maintain them in soluble, plant available form across a range of pH conditions.

Coco Chips

Coarse pieces of coconut husk that increase drainage and air filled porosity within substrate blends.

Coco Fiber

Long fibrous strands from coconut husk that improve structural integrity and aeration within the substrate.

Coco Pith

The fine sponge like fraction of coconut husk material responsible for the majority of water holding capacity in coco substrates.

Coir

A renewable lignocellulosic growing medium derived from coconut husk fiber and pith and processed for horticultural use.

Controlled Environment Agriculture (CEA)

Plant production systems that actively regulate environmental variables such as temperature, humidity, light intensity, photoperiod, CO2 concentration, irrigation frequency, and nutrient composition.

Crop Steering

A cultivation strategy that uses irrigation timing, nutrient concentration, environmental cues, and controlled dryback to influence plant hormonal signaling and direct growth patterns. By manipulating moisture availability and root zone EC, growers can affect morphology, internodal spacing, structural density, growth rate, and reproductive intensity.

Drainage Fraction

The percentage of applied irrigation volume that exits the container as leachate. Drainage fraction is used to manage salt accumulation and maintain root zone balance.

Drain to Waste

A fertigation strategy in which nutrient solution is delivered to the substrate and the resulting leachate is discarded rather than recirculated. Drain to waste systems reduce the risk of pathogen spread and simplify nutrient management by preventing accumulation of imbalanced ions in a shared reservoir. This approach requires careful monitoring of drainage fraction and root zone EC to prevent salt buildup.

Dryback

The controlled reduction in substrate moisture between irrigation events, typically measured as a percentage decrease in volumetric water content relative to field capacity. Dryback serves as a physiological signal influencing plant development.

Electrical Conductivity (EC)

A measurement of total dissolved ionic concentration in solution, expressed in mS per cm or dS per m. EC indicates nutrient strength but does not define individual element levels.

Emitter

A pressure compensating device that delivers a defined irrigation flow rate to each plant or zone.

Evapotranspiration

The combined water loss from substrate evaporation and plant transpiration.

Fertigation

The delivery of dissolved mineral nutrients through an irrigation system directly to the root zone.

Field Capacity

The volumetric water content of a substrate after gravitational drainage has ceased. Irrigation calculations are best referenced to field capacity rather than nominal container volume.

Hydroponics

A cultivation method in which plants receive mineral nutrients in dissolved form without reliance on field soil.

Hypoxia

A condition of reduced oxygen availability in the root zone, often resulting from over saturation.

Injection Ratio

The proportional dilution of concentrated nutrient stock into irrigation water.

Irrigation Shot Size

The volume of nutrient solution delivered during a single irrigation event, commonly expressed as a percentage of field capacity.

Leachate or Run Off

The solution exiting the container after irrigation. Leachate analysis provides insight into root zone EC and pH conditions.

Leaching Requirement

The calculated irrigation excess necessary to prevent salt accumulation within the substrate.

Macronutrients

Essential mineral elements required in larger quantities including nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur.

Micronutrients

Essential trace elements required in smaller quantities including iron, manganese, zinc, copper, boron, molybdenum, and chlorine.

NPK Ratio

The relative proportions of nitrogen, phosphorus, and potassium in a fertilizer formulation.

Nutrient Solution

An aqueous solution containing dissolved mineral nutrients formulated to meet crop requirements.

Osmotic Potential

The component of water potential influenced by dissolved salts. Elevated EC increases osmotic pressure and reduces water uptake efficiency.

pH

A logarithmic measurement of hydrogen ion activity in solution. In coco hydroponic systems, root zone pH is typically maintained between 5.5 and 6.2 depending on crop phase.

Porosity

The percentage of total substrate volume occupied by pore space, including both water filled and air filled pores.

Root Zone

The region of substrate immediately surrounding plant roots where water, nutrients, and oxygen are exchanged.

Run Time

The duration an irrigation zone remains active during a fertigation event.

Saturation

A condition in which all substrate pore spaces are filled with water, leaving no air filled porosity.

Stock Solution

A concentrated fertilizer solution prepared for injection into irrigation water.

Substrate

An inert or semi inert medium that physically supports plant roots and retains water and nutrients in hydroponic systems.

Total Dissolved Solids (TDS)

An estimate of dissolved ionic concentration derived from EC using a conversion factor.

Transpiration

The physiological loss of water vapor from plant leaves through stomata.

Vegetative Steering

A crop steering approach that promotes leaf and stem expansion through lower EC and shorter dryback periods.

Vapor Pressure Deficit (VPD)

The difference between the amount of moisture in the air and the maximum amount of moisture the air can hold at a given temperature. VPD is expressed in kPa and serves as a primary driver of plant transpiration. Proper VPD management coordinates environmental demand with root zone moisture availability, directly influencing nutrient uptake, stomatal conductance, and growth rate.

Volumetric Water Content (VWC)

The percentage of substrate volume occupied by water at a given time.

Water Holding Capacity (WHC)

The total amount of water a substrate can retain against gravity.

Water Potential

A measure of the potential energy of water in a system, expressed in pressure units such as MPa. Water potential determines the direction of water movement from areas of higher potential to lower potential. In plant systems, water moves along a gradient from substrate to root to stem to leaf to atmosphere. Water potential is influenced by osmotic potential, matric potential, and pressure potential and is foundational to understanding irrigation strategy and crop steering.

Wicking

The movement of water within a substrate driven by capillary forces.

 

Reference Table 1: Typical Feed EC Targets by Growth Phase

Reference Table 2: Daily Dryback Targets

Reference Table 3: Irrigation Shot Size Guidelines