Pourthrough

Pourthrough is a sampling method used in horticulture and agriculture to assess the nutrient status and salinity of the root zone by collecting the leachate that drains from a potting medium after a controlled irrigation. It is commonly used with container-grown ornamentals, greenhouse crops, and in research settings.

Procedure: a potted plant is placed in a tray; a known volume of water is applied to the substrate to produce drainage. The leachate is collected from the drainage hole, and its electrical conductivity (EC) and pH are measured. Samples may be analyzed for nitrate, ammonium, phosphate, potassium, and other ions as needed. Comparisons are made to crop- or substrate-specific targets.

Interpretation: higher EC or ion concentrations indicate greater soluble salt or fertilizer levels in the root zone; very low values may indicate leaching beyond the root zone or insufficient watering. Results are influenced by substrate type, water quality, pot size, and irrigation practices.

Applications and advantages: pourthrough is widely used in greenhouse production and research because it is fast, inexpensive, and minimally invasive; it supports nutrient management decisions without requiring tissue sampling.

Limitations: the method measures only soluble ions in leachate at a single time point and may not reflect the plant's tissue status; results depend on many procedural factors and may not capture immobile nutrients or root uptake efficiency.

See also: leachate analysis, nutrient management, substrate testing, soil testing, electrical conductivity.