EFFECT OF IRRIGATION DURATION AND FERTILIZER RATE ON PLANT GROWTH, SUBSTRATE SOLUTION EC AND LEACHING VOLUME
Container grown plants are often over-irrigated due to a lack of knowledge of how much water plants need to support optimal growth. Excessive irrigation often leads to fertilizer leaching, necessitating additional fertilizer applications. We examined the effects of fertilizer rate and irrigation duration on plant growth, substrate solution electrical conductivity (EC), and leachate volume and EC. Lantana camara Sunny Side Up plants in 3.7 L containers were fertilized with one of six levels of controlled release 16-6-11 fertilizer [25, 50, 75, 100, 125, and 150% of the labeled rate (17.7 g/pot)] and irrigated for 15, 20, 25, or 30 s during each watering event. This resulted in 24 (6 fertilizer rates × 4 irrigation durations) treatment combinations per block. When the substrate water content of the plant in the 100% fertilizer rate and 15 s irrigation duration dropped below 0.45 m3m-3, all plants in that block were irrigated (for 15, 20, 25, or 30 s, resulting in different irrigation volumes). Leachate volumes increased over the course of the study as irrigation events became more frequent due to increasing plant size, with longer irrigation durations producing more leachate. Shoot dry weight generally increased with increasing fertilizer rate, but was not affected by irrigation duration. Substrate solution EC decreased over time, regardless of fertilizer rate or irrigation duration, suggesting that plant nutrient uptake and nutrient leaching exceeded nutrient release from the controlled release fertilizer. All plants supplied with the 50% fertilizer rate or greater were considered salable, regardless of irrigation duration. Plants can be grown to a salable size with reduced fertilizer rates with small, but frequent, irrigation applications, reducing fertilizer costs, leaching, and the potential impact of nutrient-laden runoff on the environment.
Bayer, A., Whitaker, K., Chappell, M., Ruter , J. and van Iersel, M.W. (2014). EFFECT OF IRRIGATION DURATION AND FERTILIZER RATE ON PLANT GROWTH, SUBSTRATE SOLUTION EC AND LEACHING VOLUME. Acta Hortic. 1034, 477-484
volumetric water content, controlled release fertilizer, soil moisture sensor, automated irrigation, electrical conductivity, container plant production