Improvement of Plant Quality with Alumina-Buffered Phosphorus Fertilizer Progress Reports - June 1999
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
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)
