ISHS Acta Horticulturae 511: XXV International Horticultural Congress, Part 1: Culture Techniques with Special Emphasis on Environmental Implications - Nutrient Management
EFFICIENT FERTILIZATION OF NURSERY CROPS - PLANT CONTROLLED UPTAKE |
| Authors: | James L. Green, B. Blackburn, S. Kelly, M. Albahou |
| Abstract:
In the closed insulated pallet system (CIPS), movement of applied plant fertilizer protected within the root zone from evaporative and gravitational water flow pathways can be predicted by Fick's Laws of Diffusion. Ion diffusion occurs in the absence of plant uptake, but rapid plant uptake will increase the effective rate of diffusion. Water moves upward into the plant rootzone from a subirrigation reservoir by capillary and absorptive forces to achieve equilibrium; further capillary flow of water occurs in response to plant root uptake. Plant growth in CIPS has been equal or greater compared with that in a sprinkler irrigated open container system (OCS). Water uptake in CIPS has been 10% of that applied in the OCS. Plant uptake of fertilizer in CIPS has been 0.1 – 1.0 gram of nitrogen per 3 liter-container plant per year; this is less than 10% of the fertilizer applied to plants in OCS. Suaeda salsa planted as a biodesalinating companion plant with tomato in CIPS reduced sodium accumulation in the root media by 50%. In CIPS, the root system was divided between the capillary water uptake pouched media and the fertilizer reservoir media in a moisture impermeable pouch. Roots in the capillary pouch moved water by hydraulic lift across the base of the plant with outflow from the roots into the fertilizer pouch. Solubilized fertilizer was taken up by roots in the fertilizer pouch to support plant growth. In this divided root system, water uptake, water outflow and nutrient solubilization, and nutrient uptake are controlled by the plant. | |
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