ISHS Acta Horticulturae 779: International Symposium on Growing Media
POURTHRU: A METHOD FOR MONITORING NUTRITION IN THE GREENHOUSE |
| Authors: | T.J. Cavins, B.E. Whipker, W.C. Fonteno |
| Keywords: | bulk solution displacement, electrical conductivity, leachate, pour-through, SME, soil testing |
| Abstract:
The purpose of this research was to adapt the PourThru nutrient extraction technique, which is a displacement of the bulk solution from the production container without a destructive harvest, to commercial greenhouse production. PourThru is a quick and easy nutrient sampling technique that is done in the greenhouse and can help prevent nutritional problems for growers. Previous PourThru research had focused on techniques for use on large outdoor nursery containers (˜3800 cm3), while this work focused on effects in smaller (˜1700 cm3) containers. Studies were conducted on the relationship of PourThru values to saturated media extract (SME), the variation caused by different irrigation systems, timing effects on PourThru results, as well as the development of recommended influent and leachate volumes to ensure an unadulterated sample. Calibration curves were developed between PourThru and SME values and r2 values ranged from 0.91 to 0.99 for pH, electrical conductivity (EC), and nutrients. The type of irrigation systems did affect EC values and alternative standard values were developed for irrigation system. Timing of the PourThru was important to ensure adequate leachate was collected for sample analysis. The amount of influent affected EC values and the amount of leachate collected. | |
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