In the research discussed below, a "partial saturation ebb and flow watering" (PSEFW) system was used in which water was delivered and removed very rapidly. The floor sloped from two opposing sides down to a line of holes (16.5cm diameter) through which water was delivered and drained.
Zonal pelargoniums were grown in 15cm pots filled to a depth of 8.5cm with 0.88 litres of a peat (83 per cent) and perlite (17 per cent) substrate. The pots stood on the concrete floor and water was delivered for just three minutes, during which it reached a depth of 4-6 cm, before draining in two minutes.
In that time, the substrate took up 75 per cent of the water uptake of pots irrigated by the standard slow cycle where water was supplied for 10-12 minutes and required three minutes to drain.
Consequently, the average water content of the substrate was lower with PSEFW and plants were shorter - a desirable outcome with many species. However, the main benefit was that less water was needed to produce unit increase in plant dry weight.
Dr Ken Cockshull, Associate Fellow, Warwick Crop Centre, University of Warwick
Water and Nutrient Uptake and Use Efficiency with Partial Saturation Ebb and flow Watering by Gent and McAvoy (2011).
HortScience 46 (5): 791-798. ISHS members can view HortScience from the website www.ishs.org.