Managing irrigation by measuring leachate

Authors: OKI, LOREN - University Of California; Owen Jr, James - Jim

Submitted to: Greenhouse Product News
Publication Type: Popular Publication
Publication Acceptance Date: 3/30/2020
Publication Date: 4/1/2020
Citation: Oki, L.R., Owen Jr, J.S. 2020. Managing irrigation by measuring leachate. Greenhouse Product News. 30(4):26-27.

Interpretive Summary: Irrigation management in nursery and greenhouse production can be very difficult since there are numerous factors that influence the irrigator’s decisions. When fine-tuning your irrigation schedule, the amount of water you irrigate needs to, at minimum, replace the water that is used by the plant (transpiration) and evaporated directly from the substrate into the atmosphere (evaporation). Plants will use the majority or all the available water in the substrate, however, they will be selective when taking up salts creating a buildup of salts over time. Therefore, water quality must also be considered since water includes salt in additional to the mineral nutrients (i.e. more salts) from your fertilizer. Leaching fraction tells you if you are applying too little, too much, or just the right amount water when you irrigate. The method considers the water use of the crop, effect of the crop canopy, and substrate properties. If you have or are prone to salt issues, measuring the leaching fraction can inform you if you are adequately applying enough water to leach salts that are accumulating in the substrate. This article provides details of on an-easy-to-use method to measure leaching fraction to better schedule irrigation and avoid the salt build up that can be detrimental to your crop.

Technical Abstract: Irrigation management in nursery and greenhouse production can be very difficult since there are numerous factors that influence the irrigator’s decisions. When fine-tuning your irrigation schedule, the amount of water you irrigate needs to, at minimum, replace the water that is used by the plant (transpiration) and evaporated directly from the substrate into the atmosphere (evaporation). Plants will use the majority or all the available water in the substrate, however, they will be selective when taking up salts creating a buildup of salts over time. Therefore, water quality must also be considered since water includes salt in additional to the mineral nutrients (i.e. more salts) from your fertilizer. Leaching fraction tells you if you are applying too little, too much, or just the right amount water when you irrigate. The method considers the water use of the crop, effect of the crop canopy, and substrate properties. If you have or are prone to salt issues, measuring the leaching fraction can inform you if you are adequately applying enough water to leach salts that are accumulating in the substrate. This article provides details of on an-easy-to-use method to measure leaching fraction to better schedule irrigation and avoid the salt build up that can be detrimental to your crop.