Improvement of Plant Quality with Alumina-Buffered Phosphorus Fertilizer Progress Reports - June 2000
Improvement of Plant Quality with
Alumina-Buffered Phosphorus Fertilizer
Kathleen M. Brown and Jonathan P. Lynch
Dept. Horticulture,
Penn State University
Terrill Nell
Dept. Environmental Horticulture,
University of Florida
Industry Needs Addressed
With financial support from AFE, we have developed a novel fertilizer
technology for container plants that provides continuous, optimal levels of
phosphorus to plant roots based on actual plant phosphorus requirements, while
eliminating leaching from the container. Plants grown using this alumina-buffered
phosphorus fertilizer are of equal or better quality than conventionally grown
plants and have improved tolerance to drought stress. Leaching of phosphorus is
drastically reduced, especially compared with use of soluble fertilizers, but
even compared with slow release fertilizers such as Osmocote. Thus, the two
major benefits are improved plant quality and reduced pollution.
Progress Report:
Penn State University trials:
We have developed a new method for producing buffered phosphorus using
cheaper raw materials and tested this in geranium production. The product
produced with the alternative raw material successfully supplied P to the
growing geranium plants, so that dry weight accumulation was equal to
conventionally (soluble 15-15-15) fertilized plants during the first 6 weeks
after transplanting.We have developed a new method for loading alumina with phosphorus which is
simpler and better adapted to industrial-scale production. We have identified
new industry partners who are able to produce alumina-buffered phosphorus on a
commercial scale. These materials will be tested on campus and at Yoder Bros
(see below).
University of Florida trials:
We have run several trials at UF (with Dr. Nell), testing mum cuttings
grown at Yoders (below, from their stock plants started in 1998) and
poinsettias in media amended with Al-P. We have had problems with our trials
there, in each case finding poor growth of plants grown in Al-P. Since the
Al-P worked so well at other sites, this was puzzling, but it turns out that
the fertilizer used in the Al-P treatments (15-0-15) lacked magnesium, and the
symptoms were consistent with Mg deficiency. The difference between UF and
other sites may have resulted from the presence of Mg in most irrigation
waters but not at UF. We have amended the fertilizer formula for the Al-P
treatments so that all nutrients are balanced and are now doing a trial on
mums to be grown to maturity.
Trials at Yoder Brothers, Alva, FL
As mentioned in our last progress report, chrysanthemum stock plants were
grown in raised sand beds beginning in October, 1998. The experimental design
permitted evaluation of both cutting quality and leaching in replicated plots.
As previously reported, cutting production was equal to controls and leaching
was dramatically reduced. At the end of the production cycle for these plants,
they were removed and the beds prepared for replanting. We suspected that over
the long term, phosphorus would be depleted from the Al-P (mostly by being
taken up by the plants), so we developed a method for reloading the alumina
on-site (i.e. in the beds). This was done in April, and mums were replanted in
the same plots for evaluation of quality and leaching, and for the ability of
the reloaded Al-P to continue to supply adequate phosphorus. Initial leachate
sampling from the plots after reloading with phosphorus showed that charging
caused only a transient rise in P release from the plots, which was about
one-third the magnitude of P released from control plots to which no
additional P was added (i.e. residual P in those plots). The Al-P then resumed
buffering at the expected low rates of P availability.
Application for continued funding
This technology will only be available to the horticulture industry if it can be
manufactured efficiently and economically and has long term benefits for
growers. In this stage of the project we are addressing this by evaluating a new
material amenable to large-scale manufacturing and by evaluating long term field
performance (after recharging).
Objectives for the coming year:
1) Continue testing Al-P, particularly at commercial sites for long-term
use. We need to continue evaluating the site at Yoder’s for performance after
recharging. We have never tried this before so this will be all new
information.
2) In collaboration with industry partners, develop manufacturing methods for
large scale production with alternative loading techiques. This new product
and technique is more efficient and more environmentally friendly, but needs
to be evaluated in the field.
3) We will continue to evaluate postharvest quality and shipping tolerance at
UF. This is an important aspect of plant quality that we have not adequately
tested.
Professional/ published information
Brown, KM, C Miller, L Kuhns, DJ Beattie, JP Lynch. 1999. Improvement of
rhododendron and forsythia growth with buffered-phosphorus fertilizer. J.
Environ. Hort. 17:153-157.
Lynch , Jonathan and Kathleen Brown. 1999. Intelligent Media: Use of Buffered
Phosphate for Production of Ornamentals in Soilless Media. Annual meeting of
American Society for Horticultural Science, Minneapolis. (invited paper for
workshop)
