Evaluating Paper Sludge in Container Media Used for Mum Production Progress Report — December 1994
Date December 29, 1994
Title of Project Evaluating Paper Sludge in Container Media Used for Mum Production
Institution where work is being conducted University of Idaho, Moscow
Amount of Endowment Grant $3,500
Covering Period Feb. 1994 to Jan. 1995
Anticipated Date of Project Completion/Final Report December 31, 1994
Individual(s) Conducting Project:
(List Project Leader First)
Robert R. Tripepi - Title Associate Professor
Telephone Number 208/885-6635
Evaluating Paper Sludge in Container Media Used for Mum Production
Robert R. Tripepi
University of Idaho
- A. Project Objectives:
- The goal of this study was to determine the effects of mediaamended with composted paper sludge on the growth of’iridon’chrysanthemum
produced under a commercial production regime.
- B. Summary of Work Conducted:
- The European pot mum system was used as the growing regime for the mumcrop. Three cuttings of ‘Iridon’ chrysanthemum (Dendranthema x grandiflora Tzvelev.) were
planted in each 4-inch pot containing Metro-Mix 360, Sunshine Postharvest mix, composted
paper sludge combined with perlite and vermiculite
(75%:15%: 10% by volume), or composted paper sludge combined with peat moss and
perlite (50%:33%:17% by volume). Initial chemical and physical properties of the media
were determined. The crop was fertilized during each irrigation with 17-5-24 at a rate of
350 ppm N until the last month of production and received tap water thereafter. The crop
received two weeks of long-day treatments, was pinched, and then received short-day
treatments. The crop also received four treatments of 2,500 ppm B-9 during production.
The mums were not disbudded and grew for a total of 12 weeks before pot height, pot
width, number of axillary stems, number of open flowers, and total number of flowers were
determined. At the end of the experiment, half of the plants grown in each medium were
destructively sampled for stem diameter, shoot dry weight, and foliar nutrition. The other
half of the plants were watered to field capacity and allowed to dry down in a postharvest
experiment.
- C. Final Results:
- ‘Iridon’ mums planted in paper sludge-amended media grewabout as well as those potted in the two commercial mixes (Figure 1). Mums grown in
either sludge-amended medium were slightly shorter (about 5/8 inches) than those grown
in Postharvest mix but about equal to those planted in the Metro-Mix. Average pot width
of mums grown in sludge-amended media was about 1 inch less than that of mums grown
in Postharvest mix. The average number of open flowers (an indication of plant maturity)
and average number of axillary stems after pinching were unaffected by media. The
greatest affects of the media were on the total number of flowers and total shoot biomass,
with plants grown in paper sludge producing, on average, eight fewer flowers (per pot)
and 3.5 grams less shoot dry weight. Although eight fewer flowers could be considered
significant, the plants in the experiment were not disbudded, and the average number of
flowers per pot was 75 for mums grown in sludge-amended media but 87 or 83 flowers
per pot for plants grown in Postharvest or Metro-Mix.
- Foliar nutrition of plants grown in either sludge-amended medium was generally betterthan that of plants grown in either commercial mix. For instance, leaves on plants grown
in sludge-amended media contained higher levels of N, P, K, Mn, Zn, and Mo than leaves
of plants grown in the commercial mixes. Leaves from mums planted in 75% sludge also
contained more Fe than leaves from plants grown in any other media. In contrast, leaves
of plants grown in Postharvest or Metro-Mix media contained more Ca and Mg than
leaves from plants grown in sludge-amended media. These data indicate that the sludge
may have been a slow-release source of nutrients like N, P, K, and some micronutrients.
Perhaps the biggest difference between commercial and sludge-amended media was
plant response to the media immediately after planting. Some mums that we received
were slidhtly damaged during shipment (the cuttings were jumbled in the box). Within one
day after planting, some margins on new leaves on these dumbled) cuttings were brown
and appeared desiccated for plants grown in paper sludge-amended media. After one
week, only five or six plants grown in commercial media had very slight leaf damage,
where, as plants in all 20 pots which contained sludge-amended media had some signs of
damage, ranging from sight to moderate damage. Even though some plants grown in
sludge were damaged early in the study, they readily recovered within two weeks.
- Some of the plant rowth responses to sludge-amended media can be explained by theinitial chemical and physical characteristics of the media. Sludge-amended media
contained 3.2 fold more nitrate-N and almost twice the amount of P than the commercial
mixes, but the initial pH of the former media was near 4.1, 2 units lower than that of the
commercial mixes. In addition, initial electrical conductivity (EC) of sludge-amended
media was about 4.6 dS/rn (millimohs/cm) and at least double that of the commercial
mixes. These high EC levels would partially explain the leaf desiccation and margin
damage seen within two days after planting. Sludge-amended media were better aerated
but held slightly (but significantly) less water than the commercial mixes. Plants grown in
sludge-amended media may have been slightly shorter and narrower than those grow in
the commercial mixes since the former plants tended to become dry a little more quickly
than those in the latter mixes.
- The postharvest characteristics of all plants were similar, regardless of the media theywere grown in. All plants wilted about one week after starting at field capacity whether they
were planted in sludge-amended or commercial media.
- D. Future Plans Covered by the Endowment Grant:
- Composted paper sludge from a newsprint mill can be used togrow good quality pot mums. Paper sludges, however, differ from mill to mill, and sludges
from other sources should be checked before recommendations can be made about their
use. I am particularly interested in using paper sludge from newsprint mills that recycle
newspapers and magazines. In my opinion, this type of sludge would be less salty and
contain fewer phenolics that could harm herbaceous crops like chrysanthemum.
Composting paper sludges may also be unnecessary, and use of raw sludqe would save
money by avoiding extra handling of the material. Future grant proposals to the AFE may
request funds to examine the growth of floral crops in paper sludge from recycled
newsprint or in raw (noncomposted) newsprint sludge.
- E. Anticipated Benefits for Floral Industry:
- Peat moss is an important component in soilless potting media,but its price has forced growers to seek other sources of organic amendments. Pot mum
producers need organic amendments that are stable with regard to decomposition,
provide proper aeration and water-holding capacity, are nontoxic to plants and people
(workers and customers), and support plant growth. This experiment demonstrated that
composted pulp and paper sludge can be used as the major component in a soilless
potting mix for ‘Iridon’ mum production. Although plants grown in sludge-amended media
grew slightly less than those in commercial media, plant quality and appearance as well as
postharvest quality were similar among all plants. Two other mum cultivars, ‘Tara’ and
‘Pink Arola’ also grew well in sludge-amended media, but results from this part of the study
were excluded from this report due to the limited space requirements for this final report.
Pot mum growers may be able to reduce their production costs by decreasing their use of
peat-based media and using sludge-amended mixes instead. Sludge-amended media
may provide a potential advantage for growers trying to maintain shorter plant height by
using fewer chemicals. In addition, mums grown in sludge-amended media had fewer
axillarv flower buds which may reduce the amount of time needed to disbud the plants.
The pH and EC of sludge-amended media, however, should be checked before planting
and adjusted as needed since stressed mum plants initially had problems growing these
media. Since sludges vary from mill to mill and have different characteristics depending
on the type of paper production, growers should always grow a few plants in the sludge
before planting an entire crop in the medium.
- Pulp and paper sludge from a particular paper mill should be relatively consistent duringthe year, providing growers with a low cost material. In fact, since the paper industry has
a sludge disposal problem, growers may receive the material for free or be paid to take it.
Given the benign nature of pulp and paper sludge from newsprint processing (i.e., lacks
heavy metals, toxic organic compounds, and pathogens), growers should consider using
this material for plant production.
