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THE USE OF COMPOST

AS GREENHOUSE GROWTH MEDIA

Final Report

Ministry of Environment and Energy

THE USE OF COMPOST

AS GREENHOUSE GROWTH MEDIA

Final Report of A Study Conducted

for

Waste Reduction Branch, Ontario
Ministry of Environment and Energy, 135 St. Clair Ave. W.Toronto, M4V 1P5
(Project Co-ordinator: Mr. Brian Van Opstal)

at

The Composting Council of Canada
16 Northumberland St., Toronto, M6H 1P7
(Executive Director: Ms. Susan Antler)

by

Sukhu P. Mathur
Dr. S.M. Compost & Peat Specialist Inc.
75 Foxleigh Cres., Kanata, Ontario, K2M 1B6

and

Bruce Voisin
All Treat Farms Ltd., 198 Catherine St., Arthur, Ontario, N0G 1W0

October, 1996

PIBS 3458E

ISBN 0-7778-5695-6

ACKNOWLEDGEMENT AND DISCLAIMER

This report was prepared for the Ontario Ministry of Environment and Energy as part of a Ministry-funded project. The views and ideas expressed in this report are those of the authors and do not necessarily reflect the views and policies of the Ministry of Environment and Energy, nor does the mention of trade names or commercial products constitute endorsement or recommendation for use. The Ministry, however, encourages the distribution of information and strongly supports technology transfer and diffusion. Any person who wishes to republish part or all of this report shall apply for permission to do so to the Waste Reduction Branch, Ontario Ministry of Environment and Energy, 40 St. Clair Ave. W., 7th floor, Toronto, Ontario, Canada M4V 1M2.

TABLE OF CONTENTS

TABLES

EXECUTIVE SUMMARY

The objective of this study was to determine the feasibility of replacing with compost all or part of the peat moss currently employed in greenhouse growth media, in the hope of developing a high value market for composts, while increasing profits for the greenhouse industry by demonstrating the usefulness of a relatively inexpensive and easily available material.

Seven Ontario composts and seven commonly used or widely marketed peat-rich growth media were analysed to determine their contents of important total and immediately plant-available forms of nutrients. Two each of the peat media and composts were selected. These four and their eight mixtures containing 40 or 75% compost by volume, twelve media in all, were studied.

The twelve media were saturated with water and subjected to suction to determine their water-retention and supplying capacities.

It was found that on a unit weight basis three of the compost-peat mixtures had water retention and supplying capacities that were similar to those of a peat medium alone.

On the more relevant unit volume basis, five of the compost-peat mixtures and one compost were found to have higher water-supplying capacity than the two peat media. At the same time, in the more relevant moist, rather than dry state, three of the compost-peat mixtures were only marginally different from peat media in bulk density (0.95, 1.2 and 1.24 times heavier than a peat medium). This is relevant both for transportation costs and for stability of pots against tipping, particularly when growing tall plants.

A tall perennial ornamental, Clematis, and a shorter perennial, Mums, were used in a greenhouse study.

Where comparisons were valid due to survival of all triplicates, the height of the plants on day 41 on four different compost-peat mixtures were 90, 86, 79 and 81 cm, similar to the 87 cm on a peat medium. The number of leaves were 54, 46, 52 and 44 vs. 41 on the peat medium. These numbers, however, do not reveal the most significant fact that Clematis growing on the compost-peat mixtures were much healthier so that the fresh weight of stems and leaves on them were 4.9, 4.2, 5.6, and 4.4 g as compared to the 2.5 g on the peat medium, after 90 days of growth. This evidence of the advantage of including composts was corroborated by the generally higher levels of mineral nutrients in the plants grown on the compost-peat media, despite the greater growth which generally lowers the nutrient levels by the dilution effect, due to increase in plant mass.

This ability of composts to support growth of greater mass of better nourished plants was reflected in the higher contents of total and available mineral nutrients in compost-peat mixtures, even after 90 days of growing Clematis. For example, the peat media had 2 and 11 ppm of nitrate while seven of the eight compost-peat mixtures had 25 to 68 ppm nitrate (mean 50 ± 7; n=7) in them.

The higher fertility levels of composts and compost-peat mixtures, compared to the peat media, and the richer nutritional status of the plants grown on the former group were also evident on Mums grown for 77 days, although some dilution effects were discernible.

The data on growth of Mums showed that great care should be taken in selecting a growth medium, but that a substantial part of the best-performing commercial peat-rich medium can be replaced with a proper compost. In the case of some peat-rich media, partial replacement with a well-selected compost would save costs as well as support greater growth of plants that would survive better during market display and upon transplanting.

The research thus showed that it is feasible to replace a substantial part of the peat in greenhouse media with good quality composts while maintaining:

  • availability of water to potted plants, and
  • stability of pots;

    and improving the

  • crop yields (both foliage and dry matter)
  • survival of plants during market display
  • viability of plants upon transplanting
  • the level of nutrients in the plants
  • fertility of the growth media in the short and long terms
  • the profit margin for the greenhouse industry by reducing material costs, improving plant viability and shelf life during market display without significant increase in transportation costs.

Additionally, compost inclusion is likely to suppress diseases, as a bonus.

1. INTRODUCTION

Growing plants in containers indoors or outdoors requires good growing media. Earlier use of soil rich in new humus, and well rotted manures, fell in disfavour as ley cropping i.e. fields under grass-legume mixtures which provided the good quality soil, became less frequent with the progress of mechanization and specialization in agriculture (Bunt 1988). Concurrently it was increasingly realized that soil lacks uniformity and consistency from one batch to another. Soils have to be pasteurized at great cost to eliminate diseases and pests, while the risk of presence of herbicides is virtually unavoidable. Also, soil does not hold as much water as do some other materials thus necessitating watering at high frequency. Soil is heavy and subject to compaction. This curtails the supply of air to roots which get all their oxygen for the life-sustaining respiration from the surrounding medium, not from the aerial parts of the plant. There is no diffusion of air from the sides of a pot; therefore the media has to be porous and light enough to achieve aeration while it should not be prone to undergo so much biological oxidation that the decomposer microbes compete significantly with the live roots for oxygen.

The container plant industry therefore uses (McNeill et al. 1983) many lightweight (60 to 100 kg/m³ or 60 to 100 g/L) inorganics, such as vermiculite and perlite, non-biodegradable organics such as polystyrene, or virtually biostable organic materials such as old bark (composted for up to 40 years), and peat moss; although these materials are not as good at anchoring the plants as the heavier soil nor do they carry many plant nutrients. Sand is sometimes added merely to lend weight and stability to containers, preventing them from toppling over. Fertilizers have to be added to soilless mixes to provide plant nutrients.

Vermiculite is a sterile mica compound that has been heated (>750° C) to expand the clay and destroy its shrinking and swelling property while retaining its high cation exchange capacity (CEC). The high CEC enables it to carry basic plant nutrients in a plantavailable form. Vermiculite increases air porosity, water retention capacity, and wettability of the medium while it contributes some of the 6% K and 20% Mg present in its chemical structure. On the negative side, vermiculite is subject to physical breakdown when wet, and to compaction. Other baked clays and shales available have some attributes of vermiculite (McNeill et al. 1983).

Rock wool is a fibrous insulating material produced from a granite like rock called diabase or basalt. The fibres are glued with resins to produce blocks or slabs with wetting agents to serve as an inert growth medium (Papadopaulos, 1994). One problem is that rock wool is difficult to dispose after use (Robertson, 1993).

Another material, perlite, initially created as insulator, is like popcorn. It is produced by popping pieces of volcanic glass at high temperature (1000°C). It has no nutrients, does not retain water internally, nor is the air in the closed cells available to plants. It is inert, with negligible CEC, but does improve drainage and aeration.

All of the above inorganic materials are produced by using high levels of energy and are therefore not environmentally benign. Use of some old bark is, however, environmentally friendly and may help suppress diseases but at times risky due to presence of phytotoxic compounds and due to lack of adequate information on their physical properties during use in growth media (Hoitink and Poole, 1980). It is therefore not surprising that the most popular constituent of growth media is peat moss.

1.1 Peat Moss in Growth Media

Peat is partially-decomposed plant residues accumulated on such water-dominated terrestrial surfaces as swamps, fens and bogs. In systems where source of the water, and plant nutrients, is mainly natural precipitation, the plant that characterizes the vegetation is sphagnum moss. The moss plant is highly efficient in extracting mineral nutrients from old and dying tissues for use in new growth, without physical breakdown of the dead tissues. The accumulated tissues thus remain rigid, porous and highly acidic, and become the substratum for new plant life.

The accumulated moss is so porous that about 95% of the volume occupied by the peat moss is actually void spaces filled with air or water. Peat moss can thus hold water up to 20 times its own weight, like a sponge. The water is held so tightly physically and chemically in the fine capillaries that a moist peat that is 60% water by weight has none available for plants or microbes. Microbes in mineral soils therefore do not decompose added peat rapidly due to lack of available water around the peat particles and because they are poor in nutrients.

The lack of basic nutrients and the resultant acidity gives peat a good capacity for attracting and adsorbing positively charged ions such as ammonium (NH4+ and calcium (Ca++), that is, it has a high cation exchange capacity. This can be utilized to carry and supply plant nutrients but only in the sort term. In the long term, peat moss is a poor source of plant nutrients. It has little, if any, humus, the natural organic storehouse of nutrients.

But, peat moss is used as a part of growth media for greenhouse culture mainly because it (cf Pryce, 1991):

  • provides porosity;
  • enhances water holding capacity;
  • carries added nutrients in readily available form;
  • lightens the soil, thus reducing resistance to root penetration and growth;
  • does not increase danger of plant disease as it is free of relevant plant (and animal) pathogens;
  • does not compete with plant roots for soil nitrogen and soil oxygen as, being virtually biostable, it does not undergo oxidative microbial decomposition to any significant extent.
  • is relatively free of soluble salts, weed seeds, toxic heavy metals, and contraries (glass, plastics)
  • being biostable, can be stored indefinitely in an air-dry state in bags or sheltered piles without nuisance of odours or pests, and poses no hazard of spontaneous fire.

The disadvantages of using peat include a very poor nutrient status, difficulty in rewetting of dry peat (irreversible drying), and extremely low bulk density (60 g/L) that renders pots unstable particularly outdoors. But the main challenge to continued use of peat in horticulture has come from the environmental and aesthetic perspectives, although Rubec (1993) and Robertson (1993) have argued that peat extraction from wetlands can be environmentally sustainable in Canada and U.K., respectively.

It has been stated that of all the natural ecosystems, peatlands are the most susceptible to irreversible damage (Barber, 1993). Barkham (1993) has listed the value of peat bogs under the following criteria, approximately, as follows:

1.Wilderness:offer the least disturbed natural landscapes
2.Wildlife interest: peat as a soil that is mostly water (up to 98%) provides unique islands of watery ecosystems for special life forms and assemblages.
3.International heritage: they are not being formed everywhere as they were during specific geologic periods.
4.Biological indicators: show biological and environmental chemical changes as they occur ­e. g. lead pollution in air.
5.Genetic resource:e.g. various N-fixers and insecteating plants.
6.Refuges for rare species: lack of accessibility provides protection.
7.Hydrological systems:act as physical and chemical buffers between terrestrial and aquatic ecosystems
8.Unique living archives:pollen deposits provide record of past vegetations, and artefacts reflect past human cultures.
9.Carbon sinks: it is estimated that peatland contain 329-528 billion tonnes of carbon, equivalent to 1200-1900 billion tonnes of CO2 which isrelevant to greenhouse gases and climate change.

In addition to the above valid scientific reasons for conserving peatlands, and the current Sustainable Development ethos that challenges the intergenerational justice of even the slightest depletion of natural resource that can not be replaced fully, there is an emotional element in the campaign to conserve all peatlands. This was eloquently expressed with respect to one place in UK, by the english environmentalist Purseglove, (Pryce, 1991; Purseglove, 1989), as follows:

"Our destruction of places, like Hatfield Chase, for horticultural peat is the ecological equivalent of knocking down a cathedral and using the dust to line the garden path"

The Peat Campaign of the multi-sectorial voluntary group Peat Consortium in U.K. has therefore included as one of its objectives:

"development of alternative ecologically sustainable materials and practices to replace peat in horticulture, landscape and gardening industries".

The Consortium advises encouragement of research on compost as an alternative to peat, and counts marketing of the following among its achievements:

  • ICI – Coir Compost
  • A New Horizon Peat-Free Multi-Purpose Compost
  • Levington Peat-Free Universal Compost and Fisons Peat-Free Gro-Bag.

The Consortium also persuaded the U.K. Department of Transport to stop using peat for landscaping.

1.2 Alternatives to Peat

Pryce (1991) has briefly described and discussed many substitutes of peat in its various usages, including the above mentioned inert inorganics produced at high energy costs. He could have but did not refer to the attempt in Israel to obtain peat-like fibers from cow manure through expensive suspension and centrifugation steps, due to complete lack of horticultural peat in Israel. Another substitute that has been researched recently is coir from coconut (Merrow, 1994). Coir is the dust that remains after separation of the long coir fibres from coconut husk. Obviously, it has to be imported at cost from long distances for use in temperate regions. Roberston (1993) states: "In terms of bulk density, porosity and organic matter content, coir compares favourably with peat but its water capacity is lower and the more rapid leaching of nutrients may require greater fertilizer input and different management techniques. High transport costs from Sri Lanka and other sources and a certain degree of inconsistency in quality, are among the factors that may limit its wide application".

Pryce (1991) and Robertson (1993) also discussed the problems of inconsistency and limitations in terms of water retention and crop hygiene with respect to bark and other organic products, including composts.

1.3 Compost as a Substitute for Peat

Although composts are not light, i.e. as low in bulk density as peat, their inclusion in mineral soil mixes may achieve the porous state as well as peat because, unlike peat, composts contain high levels of humus, polyvalent cations, and microbial biomass. All of these three help cause individual mineral soil particles to form aggregates which provide a crumbly structure to the soil so that the medium has an appropriate soil-air-water regime. There are micro pores within soil crumbs in which water is held, and in which microbes and nutrients are transported. There are macro pores between the crumbs so that air can permeate easily and excess water flows out readily.

Unlike peat, composts have nutrients in a great variety of forms (analogous to a series of interconnected cascading pools) so that in the long term composts are a better source of plant nutrients.

Although the water holding capacity and buffering capacity of composts are not as high as those of peat on a unit weight basis, they are not very different on a unit volume basis. Consequently, composts would achieve the same objectives as peat in a growing medium mix when the two are added on equal volume proportion basis. Obviously, on a weight basis, the composts addition would be a few fold greater than that of peat. The advantages of cost, environmental benefits and ready availability, however, would still make the compost more attractive than peat, provided the compost is hygienic, mature and of high quality (BNQ Grade AA).

An example of such a good quality product is the Grade AA compost according to the National Standard of Canada (CAN/BNQ 0413200). It contains, on dry basis, more than 50% organic matter, has a C/N ratio less than 25, a MPN count of 1000 fecal coliforms/g, no salmonella, causes no net degradation due to metal contents, is 99.9% devoid of foreign matter >2 mm in size, and is truly biomature so that it does not inhibit seed germination. Such a compost fertilizes as well as improves soils, without increasing the weed problems or harbouring plant disease. It will lighten growth media while it retains and supplies nutrients as well as water to plants. Being well humified it provides a haven for a wide variety of microorganisms and biological agents. A healthy and biodiverse population of organisms is inimical to disease causing agents (pathogens). The physical and chemical attributes of such a compost also promote soil conditions and plant vigour that disfavour diseases. For example a mature compost does not compete with plant roots for oxygen needed by them to respire vigorously to ward off dampness that encourages so many diseases. In fact the composts cause soil structure that favours movement of excess water and stale air.

In discussing compost as a substitute for peat, Robertson (1993) of the U.K. Peat Producer's Association, contends that the main problems "relate to energy costs of pre-treatment and transportation, separation and composting as well as to inferior water holding and air capacities. Materials of organic origin can be highly unstable under storage, contain plant and animal pathogens, have high and often variable nutrient and salt contents and may require special treatment such as controlled composting before use". The answers to Robertson's concerns are (a) that the environmental benefits of composting are far greater than environmental costs particularly when one considers adverse impacts of waste disposal, (b) composts from well-defined and controlled feedstocks can be consistent in all respects, and perhaps more so than peats and that (c) truly biomature composts are stable, hygienic and would require no further treatment.

What is needed is a well planned and scientifically valid demonstration that a good quality compost of high organic and nutrient contents provides not only a good physical state but also better sustenance for crops for a longer period. And, unlike the failed attempts at total replacement with a compost of doubtful quality that Robertson (1993) mentioned, the first efforts should be to demonstrate partial replaceability of the peat with a good quality mature compost, and that was the purpose of this study, elaborated as follows.

1.4 Objective

To determine the feasibility of replacing peat moss with compost in greenhouse growth media.

2. MATERIALS AND METHODS

2.1 Commercial Peat-based Greenhouse Growth Media

The following identifies the seven commonly used or widelymarketed commercial peat-based media (Com. Peat Med.) studied, and their main components.

Berger Growing Mix: 78-82% peat moss, 14-22% perlite, 0-5% vermiculite

Berger BMI Mix: long fibre blond peat moss, perlite, vermiculite.

Sunshine Mix #1: 70-80% peat moss, perlite.

Premier Pro-Mix Bx: 75-85% peat moss, perlite and vermiculite.

Premier Pro-Mix Nx: 65-75% peat moss, aged soft wood bark, perlite.

Planet Safe Pro Growing Mix: brown peat

All Treat Soil less Mix: 70-72% peat moss, 20-22% bark fines, 8-10% vermiculite.

Such media generally also contain dolomitic and/or calcitic limestone as an acidity-neutralizer, macro- and micro-nutrient fertilizers, and a wetting agent.

2.2 Sources of the Composts Studied

The following identifies sources of samples of the seven Ontario composts studied and their main feedstocks.

City of Brantford: Leaf & Yard Materials (L&YM)

University of Guelph: Cattle manure and litter

Hensall: Seed cullings and wood waste

CORCAN, Joyceville: Food and wood waste

Scott's, Milton: Food and wood waste

Port Colborne: Food processing waste and L&YM

Ontario Science Centre, Toronto: Food scrapings and wood

The above composts are not identified by source or name any where else in this report.

All composts were further cured for 21 days through incubation in 60-gallon Home Composters modified to facilitate natural aeration.

2.3 Analysis of the Media

The water holding capacity (WHC) and their water desorption attributes were determined at the Analytical Services Laboratory of the Centre for Land and Biological Resources Research, Research Branch, Agriculture and Agri-Food Canada, Ottawa.

Chemical properties of the media and their water extracts were determined at the Agri-Food Laboratories at Guelph, Ont.

2.4 Media used in the Study

Commercial peat-based growth media listed as # A and # E in Table 1 and composts identified as #4 and #5 were selected for the greenhouse plant growth study. They were mixed in two volume proportions to provide eight mixes among the twelve media described below:

  1. Peat Medium A
  2. Peat Medium E
  3. Compost #4
  4. Compost #5
  5. Mix #1. P. Med. A + Comp. #5, 60:40
  6. Mix #2. P. Med. A + Comp. #5, 25:75
  7. Mix #3. P. Med. E + Comp. #5, 60:40
  8. Mix #4. P. Med. E + Comp. #5, 25:75
  9. Mix #5. P. Med. A + Comp. #4, 60:40
  10. Mix #6. P. Med. A + Comp. #4, 25:75
  11. Mix #7. P. Med. E + Comp. #4, 60:40
  12. Mix #8. P. Med. E + Comp. #4, 25:75

2.5 Crops Grown

The popular ornamental perennials Clematis and Mums were grown on the media studied. Cuttings of Clematis (Cultivar: Comtesse de Bouchard, mauve pink) with roots were procured from Barron's Flowers of Beauville, Ont., and cuttings of Mums from Yoder Canada, Leamington, Ont. All leaves, if any, and dead or weak portions were trimmed before planting.

2.6 Greenhouse Culture

This was achieved at All Treat Farms, Arthur, Ontario under the direct care of Mr. Bruce Voisin.

Six-inch (15 cm) size plastic pots of 1.5 L (6 cup) capacity, with drainage holes, were used. Each pot contained 1 L of the medium. Water was added twice a week to resaturate the media. No problems were observed with permeation and percolation. This indicated adequate wettability, water conductivity, and air permeability, thus obviating the need for further investigation or remedial action for this aspect.

Periodically, number of leaves were counted, height of plants measured, and their appearance noted.

When it was the time for harvesting the plants for weighing yields and chemical analysis, the tops were cut at the base, chopped, and placed in perforated paper bags. The soil was separated from the roots under running water on a sieve.

3. RESULTS AND DISCUSSION

3.1 The Peat-based Growth Media

These were general purpose media, not formulated specially for one type of crop only. Despite that none of the media (Table 1) had all their water extractable nutrients within the optimum range.

It is noteworthy that the organic matter content was fairly high in all the media so that the coefficient of variance (C.V.) (standard deviation as % of mean) was only 13(%). In contrast, the CV's for water soluble phosphorus and nitrate were nearly 100%.

The organic carbon content was high and the C/N ratio was generally >40. In other types of media further decomposition of the organic portion in some of the media may deplete the nitrogen supply for growing plants. This is called nitrogen drawdown in the greenhouse industry. That, however, is not applicable to sphagnum moss peat as it is a biostable or recalcitrant material for all intents and purposes in the present context.

3.2 The Composts

Surprisingly, four of the seven composts obtained for the study had organic matter contents lower than the 55% that is the minimum for recognition as an organic amendment for soils, under the Canada Fertilizer Act (Table 2). Compost #2 and #7 with the highest organic contents were stated to be immature products, and this was borne out by their inhibition of seed germination, and by their low nitrate contents. Compost #4 was somewhat anomalous, in that although it, unlike #2 and #7, had a <25 C/N ratio, and touted as a fully processed product, it had low nitrate content, and did inhibit seed germination. Subsequent other observations suggested that it matured quickly during the incubation that was a part of this study.

As expected, the composts were generally richer than the peat media in their contents of total major fertilizer elements N, P & K. These are present in the commercial media (Table 1) mainly as chemical additives, except for the mostly non-bioavailable, about 1% total N in peat.

The pH values of the composts were generally higher than the 7.00 which is at the top of the optimum range. Further nitrification on bio-maturation generally decreases the pH. If necessary the pH can also be decreased early by inclusion of elemental sulphur that is bacterially oxidizable to the acid sulphate. The total soluble salts, expressed as electrical conductivity, were also rather high in composts but probably mainly due to potassium, calcium and nitrate rather than the more problematic sodium, carbonate, chloride, and sulphate.

The >7.00 pH of the composts would have to be remedied, particularly if it is found to decrease plant availability and uptake of P, Fe, Mn, Zn and B.

3.3 Physical and Moisture Properties of the Growth Media Used

Data in Table 3 reveal that, as expected, the peat media are generally less dense than composts with Compost #5 being 5.5 times denser than Peat Medium A. But, Compost #4 being high in organic content is only 1.4 times denser than Peat Medium E. The high organic content of a humified nature enables Compost #5 to retain water more tenaciously (Tables 3 and 4) so that 1 L of the medium would yield only 12.4 ml of water to plants before wilting occurs or 88 ml per kg compost. The corresponding values for peat media A and E are 31 and 513, and 24 and 232, respectively.

The data also show how the problem can be alleviated by the inclusion of perlite or vermiculite or both in the compost-peat mixtures. The presence of these materials in the peat media may have been responsible for the much greater availability of water from the compost-peat mixtures so that there was a greater than cumulative effect. For example, while, per litre, Compost #4 yielded only 12.4 ml of water and the Peat Medium A yielded 31.0 ml, their 75:25 combination in Mix #6 yielded 46.7 ml, while cumulatively it should have given up only 17.05 (12.4 × 0.75 = 9.3; 31 × 0.25 = 7.75); 9.3 + 7.75 = 17.05).

It is particularly noteworthy that a litre of compost #5 carried more available water than the two peat media, 37.8 ml vs 31.0 ml and 24.1 ml (Table 3).

Some combinations of the composts (Mix #'s 5, 1, and 7) in the moist state in which they are handled and transported, were only 0.95, 1.2, and 1.24 times heavier than the same volume of Peat Medium E.

This is important in the context of the popular perception that all compost-based growth media are prohibitively heavier than most peat-based media so that the greater stress in handling and cost of transportation outweigh any advantages of composts in greater physical stability of pots with tall plants (no tipping over) and in better survival in the market place due to highernutritional and moisture availability from most composts.

Chemical properties of mixtures of the composts and peat media employed in this study (Table 5) indicated that the Compost #5 with higher nitrate content (Table 2) may have undergone microbial denitrification during storage, pre-incubation and handling while the lighter (more aerobic) Compost #4 may have had nitrification along with some ammonification. Consequently, its mixture with P.M. E had higher nitrate content than either of the two constituents (24 and 37 vs. 9.01 in both - Tables 5, 2 and 1). One, however, has to exercise caution in extrapolating data from analysis of single samples, despite the care taken in ensuring homogeneity during sampling.

3.4 Growth of Clematis

It is known that 5 to 80 percent of Clematis cuttings do not survive and grow into healthy plants on planting, and that the growing plants are highly susceptible to a wilt disease, requiring special management of air and humidity in dedicated greenhouses. Additionally, the lack of experience of the supervisor of this study (S.P.M.) with Clematis may have contributed to the survival rate of the cuttings being 72.2% (26 out of 36) rather than 100%. One or two replicates of 5 out of 12 triplicated treatments did not survive, thus skewing comparisons. One must therefore consider only the treatments where all the three replicates survived on 41 days after their planting on December 1, 1995, before the plants reached the maximum height of 36" (92 cm) that was practicable in this greenhouse, i.e. Peat Medium E and Mix #'s 1, 3, 7 and 8. It is remarkable that at least one combination of both the peat media with either of the two composts supported Clematis growth to a height that was statistically similar to the one from Peat Medium A that contains the most peat (87 vs. 79, 81, 86 and 90 cm, and 41 leaves vs. 44, 46, 52, and 54). This compost-favouring evidence was strongly corroborated by the following.

The average yield of tops in ninety days from the Mix #'s 1, 3, 7 and 8 was 191% of that from Peat MediumA (4.77 vs. 2.5) and equal to the 4.8 average of the two duplicates from Peat MediumE. This was reflected in the greater root mass in Mix #'s 1, 3 and 8, compared to the 10.6 g in Peat Medium A. The possibility that the differences in yield were due to differences in initial root mass was eliminated by the fact that the root masses of P.M. A and Mix #7 were statistically similar at harvest but the tops from the Mix #7 weighed 224% of that from the peat-rich medium, P.M. A.

Logically, greater plant yield from one soil compared to another of similar nutrient status results in lower levels of nutrient elements in the former, due to a dilution effect. For example, a 68% increase in yield of Clematis tops from Mix #3 compared to Peat Medium A may have caused 27% and 32% decreases in percent N and Mg, respectively. But surprisingly, such dilution was exceptional rather than tendentious, because the plant material from the Mix #’s 3, 7 and 8 had higher levels of nutrients than the same from Peat Medium A, showing that the inclusion of composts substantially improved the nutrient status of the plants, perhaps due to presence of a broader range of forms of elements in composts than in the peat media where they are either available immediately in water soluble forms which can also be easily lost by leaching, or practically not available at all due to the recalcitrance of peat to biological decomposition.

The higher nutrient status of the compost-supported plants have many positive implications. For example, the higher N content is likely to maintain a darker green colour in the leaves during marketing display on the retailer's shelf, and the higher K content would make them less likely to lodge. The higher P content in both tops and roots would favour root proliferation on transplanting, and flowering.

It is known that higher pH than the neutral 7.0 generally suppresses plant uptake of Mn, Fe, P and B. One does not see evidence of that here, perhaps due to the high nutrient-status of the composts, one possible exception was Mn in above ground plant material from Mix #'s 7 and 8 (Table 9) which may have been mainly due to the dilution effect.

The advantage of nutrient-rich compost was also apparent in the quality of the soil remaining in the pots after the growth for 90 days and at the stage that the pots would be marketed (Tables 11 and 12). The soils in pots of Mix #'s 1, 3, 7 and 8 were richer in total N, P and K than the peat media (Table 11). The same was true of water-soluble nutrients, with one exception. Rather than being higher as was the trend, the soluble-P in Mix #1 was the same as in Peat Medium A, 2.01. In contrast, soluble-P in Mix #'s 7 and 8 were 30.01 and 21.01 respectively.

The better quality of the media remaining in mixtures with composts should enhance the quality and appearance of plants during marketing and their survival and growth on transplanting.

3.5 Growth of Mums

Unlike the case with Clematis all of the Mums cuttings planted grew well into the flowering stage in about 50 days. They were grown for 77 days in all for this study. At day 51 (Table 13) height and number of leaves were higher on Peat Medium E than on Compost #4 and its mixtures, but only marginally so. By day 77 the plant mass data (Table 14) revealed much bigger differences between the two peat media as well as between the two composts.

It was remarkable that the two peat-based media differed significantly in their support of the growth of Mums plant mass. The plant height and number of leaves were lower in Peat Medium E, compared to the same on Peat Medium A by only 13% and 25%, respectively, 51 days after planting. The actual growth in Peat Medium E in fresh weight in 77 days was only 56.8% (13.4 vs. 7.6) of the one on Peat Medium A (Tables 13 and 14).

On the same terms, the yield or top growth during the study from Compost #4 was about the same as from Peat Medium E, while the yield from Compost #5 was about half of that from Peat Medium E. In other words, the top growth during the study was about twice as much on Peat Medium A compared to E. Compost #4 gave a yield close to E. The yield from Compost #5 was only half as much as E. When Compost #4 was in combination with a peat medium the top growth was nearly as good (85 to 95%) as on the most productive Peat Medium A. This means that the addition of Compost #4 to a peat medium improved the performance of both the Peat Medium E and the compost itself, while it did not decrease the growth on Peat Medium A. And yet, the height of plants and number of leaves, showed little, if any, difference attributable to Compost #4 while Compost #5 performed poorer than both peat media and the other compost, so much so that its addition in Mix #'s 2 and 3 seemed to have marginally adverse effect on performance of both constituents.

This adverse effect was obviously not due to any nutritional deficiency as the elements were present in the plant materials grown on Mix #2 and 3 at levels equal, or greater, than those on comparable healthy plants grown on at least one medium (Tables 15 and 16). The possibility that the yield from Mix #3 may have been low due to phytotoxicity of the 411 ppm Cu, about 20 times the top of the normal range value, was discounted by the lack of high level of Cu in the roots in Mix #3. It appears from this and other instances that the Cu determination may have suffered from a procedural mishap. For example, the high-yield tops from Mix #5 (Tables 8, 16 and 17) also were found to have levels of Cu (187 ppm) that are usually phytotoxic while the roots (24 ppm) did not.

Therefore the decrease in overall growth caused by addition of Compost #5 to Peat Medium E was not due to deficiencies or excesses of nutrient elements. Further investigation of the peat medium and the compost is needed to seek explanation of this seemingly anomalous behaviour.

The greater growth in plant material, despite the lack of difference in the height of plants and number of leaves, makes the Mums grown on the Compost #4 mixes look more healthy and fleshier, compared to the same on Peat Medium E.

The data on plant growth thus shows that great care should be taken in selecting a medium for Mums, but that a substantial part of the peat in the best-performing commercial media can be replaced by a proper compost at a cost-saving without affecting growth. In other media the inclusion of a proper compost may improve growth and save costs. The following shows that the improvement will be sustained in the compost-peat mixtures.

The composts and their mixtures remaining in the pots after crop growth for 77 days to marketable state, were consistently far higher in total contents of N, P and K while their C/N ratios were lower than 25, unlike those of the peat media, so that the composts would continue to supply nitrate to the plants well into the medium and long-terms. Indeed, the water-soluble nitrate, Ca, K and Mg were higher in all composts and compost-peat mixtures than the two peat media alone. The same was also true of P except that Compost #5 and its mixtures were poorer than Peat Medium E.

As in the case of Clematis, there was no clear evidence that the higher than 7.00 pH of the composts and their mixtures caused deficiencies of P, Mn, Fe or B.

3.6 Stability of pH of the Media

pH is recognized as the single most important property of a soil as it influences all biological and chemical processes in the medium, particularly at the soil-root interface. Also, pH has a role in determining the soil physical structure through peptization, suspension of clay and humus, and its influence on cations like Ca that form bridges between particles within a crumbly aggregate.

At lower pH values, acidity decreases the availability of calcium and molybdenum when the pH is higher than 7, i.e. alkaline pH, iron, manganese, phosphorus, and boron become less available to plants.

Changing or correcting the pH of a soil or medium uniformly is difficult while a crop is standing on it.

Stability of pH of a soil or soil-less medium is important for dependable plant nutrition and health.

In this study (Table 19) the highest change in pH of a growth medium incurred in the popular Peat Medium A. The pH increased by 0.9 and 1.0 under the Mums and Clematis respectively.

The average pH change in the eight compost-peat mixtures (n=16) was less than 0.1 unit. The change in pH values ranged from -0.6 to + 0.41 with the exception of Mix #6 (-0.79). In the composts themselves pH value change ranged from -0.31 to + 0.41. In Peat Medium E the change in pH was relatively high (+0.69), but the highest change was in Peat Medium A where the pH increased by 1.0 and 0.9 units, in spite of the preponderance of peat and the presence of vermiculite. Both peat and vermiculite have high buffering capacities so that they can carry and supply large amounts of plant nutrients without a wide change in pH. The increase in pH in the P.M. A may have been effected partly by delayed dissolution of added limestone, release of K and Mg from vermiculite, and removal of the acid ions nitrate and phosphate by plants.

The nitrates and phosphates were not replaced by transformation of the N and P in the peat, as peat is biologically recalcitrant, at least in the short term. The nitrates and phosphates in a medium are mostly from added fertilizers which are readily taken up by plants or leached by irrigation water, with little or no slow-release forms of N & P in the peat to act as continual sources of nitrate and phosphate. In ontrast, composts are like natural soils in carrying the various plant nutrients in a continuous spectra of chemical forms from which forms readily plant-available forms of nutrients are released continually by chemical and biological transformations, like a series of connected cascading pools.

Mature composts, being products of long biological and chemical processes, are in a state of equilibrium and are unlikely to suffer sharp changes of the type that can occur on wetting of a dry peat mixed with powdered limestone and soluble fertilizers.

4.CONCLUSIONS

Replacement of peat-rich (70 to 80%) growth media with composts to the extents of 40 and 75% on a volume basis generated mixtures that had water retention and supplying capacities similar to those of a peat-rich medium alone, on a unit weight basis. On unit volume basis, the compost mixtures carried and supplied more water to plants grown than either of the two peat media selected for the study as the best from the seven tested. The bulk densities of some effective compost mixtures differed only marginally from those of a peat medium.

Some of the mixtures with composts supported greater growth of Clematis vines than the peat-rich media themselves. The growth of Mums also showed that a substantial portion of the peat-rich media can be replaced by a proper compost to save costs without decreasing growth in some cases and with improvements in plant growth in others.

The plants grown on compost-containing media were generally richer in mineral nutrients, as were the media remaining in the pots, compared to the plants growth on peat-rich media alone, and the peat media themselves after growth. The advantages of including composts in the growth media should therefore extend to marketing and transplanting of the potted plants.

It was therefore concluded that a good quality compost can substantially replace peat in container growth media. Such use of compost will:

  • increase plant growth;
  • improve survival of plants during marketing and upon transplanting;
  • widen profit margin for the container plant industry; and
  • be environmentally beneficial

REFERENCES

Barber,K.E. 1993. Peatlands as scientific archives of past biodiversity. Biodiversity and Conservation 2: 474-489.

Barkham, J.P. 1993. For peat's sake: conservation or exploitation? Biodiversity and Conservation 2: 556-566.

Bunt, A.C. 1988. Media and Mixes for Container-Grown Plants. Unwin Human, London.

Buckland, P.C. 1993. Peatland archaeology: a conservation resource on the edge of extinction. Biodiversity and Conservation 2: 513-527.

Hoitink, H.A.J., and M.A. Poole. 1980. Bark compost use in container media. Compost Sci./Land Utilization. 21: 38-41.

Manaker, G.H. ? Soil less media for interior landscapes. Interior Landscape Industry. ?

McNeill, D.B., T.J. Blom, and J. Hughes. 1983. Soil less Mixes. Ontario Ministry of Agriculture and Food Factsheet. AGDEX 296/510. 3 pages.

Meerow, A.W. 1994. Coir (Coconut Mesocarp Pith) as a Peat Substitute. Tropic Line (Tropical Horticulture Newsletter of the Ft. Lauderdale Research & Education Centre of the Univ. of Florida).7 (3). 1-4.

Papadopoulos, A.P. 1994. Growing Greenhouse seedless cucumbers in soil and soilless media. Agriculture and Agri-Food Canada Publication 1902/E. Ottawa.

Pryce, S. 1991. Alternatives to peat. Professional Horticulture5: 101-106.

Purseglove, J. 1989. Peat extraction and wetland destruction. Landscape Design. 182 (cf. Pryce 1991).

Robertson, R.A. 1993. Peat, horticulture and environment. Biodiversity and conservation:2: 541-547.

Rubec, C. 1993. Sustainability and peatland resources use in Canada. Paper 22. Newfoundland Peat Opportunities – An International Conference. 20 pages. Proceedings. Corner Brook, Nfld.

Table 1. Properties of Commercial Peat-based Growth Media

Commercial Peat Media Typical Values
A B C D E F G
Total Solid
Dry Matter (D.M.) % 41.41 52.44 58.25 65.66 61.73 32.74 45.07 30 – 55
Moisture % 58.58 47.55 41.74 34.33 38.26 67.25 54.92 30 – 55
Organic Matter, % DM 69.83 71.35 54.95 61.02 79.24 80.18 73.33 30
Organic Carbon, % DM 38.79 39.64 30.53 33.90 44.02 44.54 40.74 -
Total Nitrogen, % DM 0.75 0.74 0.63 0.78 0.95 1.18 0.91 >0.60
Total Phosphorus, % DM 0.06 0.05 0.08 0.08 0.12 0.23 0.22 >0.2
Total Potassium, % DM 0.22 0.25 0.06 0.48 0.10 1.24 0.57 >22
Carbon/Nitrogen Ratio 51.72 53.57 48.46 43.46 46.34 32.75 44.77
Water Extract Optimum range
pH 6.20 6.10 5.41 6.01 6.01 4.70 4.70 5.5 – 7.0
Nitrate-N, ppm 58.01 29.01 81.01 105.01 9.01 300.01 100.01 100 – 200
Calcium, ppm 77.01 68.01 107.01 99.01 59.01 472.01 96.01 200 – 300
Phosphorus, ppm 4.01 5.01 35.01 15.01 18.01 44.01 89.01 6.0 – 9.0
Potassium, ppm 41.01 42.01 115.01 58.01 51.01 1127.01 155.01 150 – 250
Magnesium, ppm 31.01 28.01 95.01 39.01 11.01 188.01 50.01 70 – 200
Total Salts, MMHO/cm. 0.78 0.69 1.52 1.11 0.57 7.54 1.34 2.0 – 3.5

Table 2. Properties of Composts

#1 #2 #3 #4 #5 #6 #7 Applicable BNQ Grade AA or Greenhouse Media Range
Total Solid
Dry Matter % (D.M.) 61.90 34.70 56.47 42.46 61.58 76.07 52.90 >50
Moisture % 38.09 65.29 43.53 57.53 38.41 23.92 47.09
Organic Matter, % DM 32.26 87.98 32.03 77.59 53.23 49.90 95.98
Organic Carbon, % DM 17.92 48.88 17.79 43.10 29.57 27.72 53.32 <25
Total Nitrogen, % DM 1.34 1.20 1.80 2.01 1.66 2.21 1.39
Total Phosphorus, % DM 0.24 0.33 0.55 0.51 0.27 0.70 0.15
Total Potassium, % DM 0.79 1.33 0.94 1.00 0.92 1.07 0.50
Carbon/Nitrogen Ratio 13.37 40.73 9.88 21.44 17.81 12.54 38.36
Water Extract Optimum range
pH 7.81 8.20 7.81 8.01 7.51 7.41 8.51 5.50-7.00
Nitrate-N, ppm 271.01 17.01 376.01 9.01 291.01 291.01 10.01 100.00-200.00
Calcium, ppm 221.01 26.01 119.01 65.01 87.01 87.01 15.01 200.00-300.00
Phosphorus, ppm 2.01 19.01 4.01 13.01 28.01 28.01 41.01 6.00-9.00
Potassium, ppm 1809.01 582.01 1466.01 849.01 1705.01 1705.01 329.01 150.00-250.00
Magnesium, ppm 108.01 12.01 67.01 28.01 80.01 80.01 2.01 70.00-200.00
Total Salts, MMHO/cm. 7.33 2.22 5.29 4.79 7.62 7.62 4.85 2.00-3.50
Percent Germination of Cress seeds (# of Control)* 90.00 80.00** 95.00 80.00 85.00 85.00 0.00**

*Compare with 90% for Peat Medium C and 54% for Peat Medium F. **Early stage composts.

Table 3. Bulk Density and Available Water in Media Saturated to Water Holding Capacity, in ml per Litre Medium

Media Bulk Density grams Dry Matter/Litre Water Content at Saturation at WHC, 0.33 bar suction ml/L medium Moist Weight at WHC g/L Available Water between 0.33 and 0.50 bar suction ml/L medium Available Water between 0.50 and 1.0 bar suction ml/L medium Total Available Water 0.33 to 1.0 bar suction ml/L medium
Peat Medium A 60.4 117.9 178.3 28.2 2.8 31.0
Peat Medium E 103.8 150.4 254.2 19.2 4.4 24.1
Compost #4 141.5 184.2 325.7 10.6 1.8 12.4
Compost #5 331.3 281.6 612.9 20.5 17.2 37.8
Mix #1 P.M. A 60 #5 Comp 40 141.1 160.5 302.4 4.81 19.0 23.8
Mix #2 P.M. A 60 #5 Comp 75 221.9 203.5 425.4 12.6 10.2 22.8
Mix #3 P.M. E 60 #5 Comp 40 241.9 265.8 507.7 21.5 25.9 47.4
Mix #4 P.M. E 25 #5 Comp 75 275.8 266.7 542.5 21.0 24.3 45.2
Mix #5 P.M. A 60 #4 Comp 40 92.1 150.4 242.5 27.3 5.7 33.0
Mix #6 P.M. A 25 #4 Comp 75 130.6 213.3 343.9 38.6 8.1 46.7
Mix #7 P.M. E 60 #4 Comp 40 127.9 188.4 316.3 28.9 6.1 35.0
Mix #8 P.M. E 25 #4 Comp 75 157.7 192.1 349.8 ND ND ND

Table 4. Available Water in Media Saturated to Water Holding Capacity, in ml per Kilogram Dry Matter

Media Water Content at Saturation at WHC, 0.33 bar suction ml/kg D.M.* Available Water between 0.33 and 0.50 bar suction ml/kg D.M. Available Water between 0.50 and 1.0 bar suction ml/kg D.M. Total Available water between 0.33 and 1.0 bar suction ml/kg D.M.
Peat Medium A 1952 ± 34 467 46 513
Peat Medium E 1449 ± 26 185 42 232
Compost #4 1302 ± 15 75 13 88
Compost #5 850 ± 30 62 52 114
Mix #1 P.M. A 60 #5 Comp 40 1134 ± 04 34 134 168
Mix #2 P.M. A 25 #5 Comp 75 917 ± 41 57 46 103
Mix #3 P.M. E 60 #5 Comp 40 1099 ± 21 89 107 196
Mix #4 P.M. E 25 #5 Comp 75 967 ± 37 76 88 164
Mix #5 P.M. A 60 #4 Comp 40 1633 ± 36 296 62 358
Mix #6 P.M. A 25 #4 Comp 75 1469 ± 18 267 23 290
Mix #7 P.M. E 60 #4 Comp 40 1473 ± 85 226 48 274
Mix #8 P.M. E 25 #4 Comp 75 1218 ± 51 9** 18** 27**

*Mean ± SEM, n = 2

**Disregard as procedural error

Table 5. Properties of Mixtures of Peat-based Commercial Growth Media and Composts

Mix #1 P.M. A 60 #5 Comp 40 Mix #2 P.M. A 25 #5 Comp 75 Mix #3 P.M. E 60 #5 Comp 40 Mix #4 P.M. E 25 #5 Comp 75 Mix #5 P.M. A 60 #4 Comp 40 Mix #6 P.M. A 25 #4 Comp 75 Mix #7 P.M. E 60 #4 Comp 40 Mix #8 P.M. E 25 #4 Comp 75 Typical Range for Composts
Total Solid
Dry Matter (D.M.) % 55.26 58.25 59.84 62.97 42.57 39.70 50.08 51.80 30 - 55
Moisture % 44.73 41.74 40.15 37.03 57.42 60.29 49.91 48.19 30 - 55
Organic Matter, % DM 31.10 54.62 60.42 56.48 70.38 68.50 75.72 72.23 <80
Organic Carbon, % DM 17.27 30.34 33.57 31.38 39.10 38.05 42.07 40.13 -
Total Nitrogen, % DM 0.79 1.67 1.34 1.67 1.74 2.24 1.63 2.20 >.60
Total Phosphorus, % DM 0.11 0.23 0.18 0.24 0.39 0.54 0.37 0.52 >.25
Total Potassium, % DM 0.27 0.76 0.46 0.71 0.43 0.74 0.40 0.72 >.20
Carbon/Nitrogen Ratio 21.71 18.17 25.05 18.79 22.47 16.99 25.81 18.24 22.0
Water Extract Optimum range
pH 7.60 8.01 7.20 7.70 7.60 8.20 7.01 7.91 5.5 - 7.0
Nitrate-N, ppm 82.01 9.01 6.01 8.01 62.01 66.01 24.01 37.01 100 - 200
Calcium, ppm 85.01 108.01 100.01 150.01 47.01 68.01 62.01 58.01 200 - 300
Phosphorus, ppm 3.01 2.01 5.01 2.01 10.01 13.01 19.01 12.01 6 - 9
Potassium, ppm 398.01 755.01 409.01 820.01 350.01 584.01 356.01 612.01 150 - 2501
Magnesium, ppm 32.01 40.01 27.01 50.01 19.01 21.01 16.01 18.01 70 - 200
Total Salts, MMHO/Cm. 2.45 3.81 2.51 4.41 2.24 3.51 2.30 3.80 2.0 - 3.5

Table 6. Growth of Clematis (ev Comtesse de Bouchard), (Mean = SEM, n = 3, 2* or 1** due to some mortality) (Tops snipped at about 92 cm, i.e. 36")

Media Days after Planting
6 14 21 28 35 41 49 56 62 69
Peat Medium A 3.2 ± 0.5 10.2± 3.2 33.0 ± 2.1 59.3 ± 3.9 83.0 ± 6.0 87.2 ± 6.9 85.5 ± 6.0 85.5 ± 6.0 85.5 ± 6.0 85.5 ± 6.0
Peat Medium E 3.2± 0.3 11.4 ± 3.8 30.5 ± 11.0 66.0* ± 0.0 86.4* ± 1.5 96.5* ± 1.5 95.3* ± 0.9 95.3* ± 0.9 95.3* ± 0.9 95.3* ± 0.9
Compost #4 3.8 ± 0.6 4.7 ± 0.9 12.7 ± 7.3 45.7** 86.4** 109.2** 91.4** 91.4** 91.4** 91.4**
Compost #5 3.8 ± 0.3 7.2 ± 2.8 16.1 ± 10.1 76.2** 96.5** 91.4** 91.4** 91.4** 91.4** 91.4**
Mix #1 P.M. A 60 #4 Comp 40 4.4 ± 0.8 8.2 ± 2.3 37.2 ± 2.8 59.3 ± 3.7 83.8 ± 6.3 89.7 ± 1.4 96.5 ± 4.2 91.4 ± 0.0 91.4 ± 0.0 91.4 ± 0.0
Mix #2 P.M. A 25 #4 Comp 75 3.4 ± 0.3 5.1 ± 1.2 11.4 ± 2.3 50.8** 76.2** 101.6** 91.4** 91.4** 91.4** 91.4**
Mix #3 P.M. E 60 #4 Comp 40 4.7 ± 0.6 9.7 ± 0.7 35.6 ± 1.2 72.0 ± 5.7 87.2 ± 5.4 86.4 ± 4.2 86.4 ± 4.2 86.4 ± 4.2 86.4 ± 4.2 86.4 ± 4.2
Mix #4 P.M. E 25 #4 Comp 75 3.8 ± 0.6 6.8 ± 2.5 4.3 ± 4.8 19.1* ± 4.5 33.0* ± 5.4 45.7* ± 14.3 74.9* ± 34.8 58.4* ± 23.2 58.4* ± 23.2 58.4* ± 23.2
Mix #5 P.M. A 60 #5 Comp 40 3.4 ± 0.3 8.7 ± 2.0 39.4* ± 0.9 73.7* ± 1.8 90.2* ± 2.7 91.4* ± 0.0 91.4* ± 0.0 91.4* ± 0.0 91.4* ± 0.0 91.4* ± 0.0
Mix #6 P.M. A 25 #5 Comp 75 3.4 ± 0.2 6.4* ± 0.9 16.5* ± 0.9 38.1* ± 1.8 61.0* ± 7.1 72.4* ± 13.4 86.4* ± 3.6 92.7* ± 0.9 92.7* ± 0.9 92.7* ± 0.9
Mix #7 P.M. E 60 #5 Comp 40 2.7 ± 0.2 10.2 ± 1.0 30.5 ± 1.2 52.5 ± 4.2 69.4 ± 4.9 78.7 ± 7.9 85.5 ± 9.0 85.5 ± 9.0 85.5 ± 9.0 85.5 ± 9.0
Mix #8 P.M. E 25 #5 Comp 75 3.2 ± 0.3 5.1 ± 1.6 17.3 ± 7.5 38.1 ± 6.3 61.8 ± 4.2 81.3 ± 4.2 110 ± 2 94 ± 0.0 94 ± 0.0 94 ± 0.0

Table 7. Growth of Clematis (cv Comtesse de Bouchard), Number of Leaves (Mean ± SEM, n = 3, 2* or 1** due to some mortality)

Media Days after Planting
14 21 28 35 41 49 56 62 69
Peat Medium A 4 ± 1 14 ± 3 27 ± 2 37 ± 2 41 ± 1 41 ± 1 41 ± 1 41 ± 1 41 ± 1
Peat Medium E 6 ± 3 16 ± 6 25 ± 10 50* ± 8 64* ± 9 64* ± 9 64* ± 9 64* ± 9 64* ± 9
Compost #4 1** 15** 24** 37** 44** 47** 45** 45** 45**
Compost #5 13** 28** 38** 50** 61** 62** 62** 62** 62**
Mix #1 P.M. A 60 #5 Comp 40 6 ± 1 6 ± 1 21 ± 3 34 ± 4 54 ± 4 55 ± 3 55 ± 3 55 ± 3 55 ± 3
Mix #2 P.M. A 25 #5 Comp 75 4 ± 3 10 ± 8 51** 60** 60** 60** 60** 60** 60**
Mix #3 P.M. E 60 #5 Comp 40 7 ± 2 19 ± 5 36 ± 5 43 ± 3 46 ± 1 47 ± 0 45 ± 1 45 ± 1 45 ± 1
Mix #4 P.M. E 25 #5 Comp 75 4 ± 3 13* ± 9 18* ± 6 25* ± 1 33* ± 5 36* ± 6 36* ± 6 36* ± 6 36* ± 6
Mix #5 P.M. A 60 #4 Comp 40 6 ± 3 29* ± 5 43* ± 2 61* ± 0 61* ± 2 61* ± 2 61* ± 2 61* ± 2 61* ± 2
Mix #6 P.M. A 25 #4 Comp 75 1 ± 0 11* ± 2 23* ± 1 33* ± 2 35* ± 4 43* ± 1 45* ± 2 45* ± 2 45* ± 2
Mix #7 P.M. E 60 #4 Comp 40 9 ± 1 21 ± 3 30 ± 3 41 ± 6 52 ± 7 56 ± 5 56 ± 5 56 ± 5 56 ± 5
Mix #8 P.M. E 25 #4 Comp 75 3 ± 2 11 ± 4 26 ± 3 36 ± 3 44 ± 1 51 ± 2 51 ± 2 51 ± 2 51 ± 2

Table 8. Yield of Clematis Plant Material (Mean ± SEM, n = 1**, 2* or 3), grams/pot

Media Fresh Weight of Stem + Leaves Fresh Weight of Roots Fresh Weight of Stems + Leaves as % of thaton Peat Medium A Fresh weight of Stems + Leaves as % of that on Peat Medium E
Peat Medium A 2.5 ± 1.0 10.6 ± 1.3 100 52
Peat Medium E 4.8* 12.4 ± 2.6 192 100
Compost #4 3.8** 9.2 ± 0.8 152 79
Compost #5 4.2** 12.0 ± 2.1 168 87
Mix #1 P.M. A 60 #5 Comp 40 4.9 ± 0.9 16.3 ± 2.8 196 102
Mix #2 P.M. A 25 #5 Comp 75 2.2** ± 0.8 11.1 ± 3.5 88 46
Mix #3 P.M. E 60 #5 Comp 40 4.2 ± 0.1 18.3 ± 2.4 168 88
Mix #4 P.M. E 25 #5 Comp 75 2.2* ± 0.4 12.8 ± 3.3 88 46
Mix #5 P.M. A 60 #4 Comp 40 5.0* ± 1.4 11.6 ± 4.1 200 104
Mix #6 P.M. A 25 #4 Comp 75 3.7* ± 2.2 12.4 ± 3.2 148 77
Mix #7 P.M. E 60 #4 Comp 40 5.6 ± 0.1 12.4 ± 4.3 224 117
Mix #8 P.M. E 25 #4 Comp 75 4.4 ± 0.1 13.6 ± 0.7 176 92

Table 9. Mineral Nutrient Contents of Clematis Tops (vines + leaves) Grown in the Various Media

Media % N % P % K % Mg % Ca ppm Zn ppm Mn ppm Cu ppm Fe ppm B
Peat Medium A 2.05 0.09 2.10 0.32 1.12 62.93 269.73 4.99 70.92 36.96
Peat Medium E 1.99 0.34 2.31 0.17 0.82 47.61 265.87 5.95 61.50 37.69
Compost #4 1.82 0.13 7.81 0.17 0.69 60.81 233.30 4.98 70.78 82.75
Compost #5 1.87 0.15 5.07 0.13 0.35 68.09 151.75 3.89 52.52 36.96
Mix #1 P.M. A 60 #5 Comp 40 1.85 0.14 4.30 0.26 0.99 110.77 258.48 6.98 121.75 39.92
Mix #2 P.M. A 25 #5 Comp 75 2.20 0.23 5.05 0.14 0.46 42.95 184.81 2.99 56.94 32.96
Mix #3 P.M. E 60 #5 Comp 40 1.50 0.14 3.82 0.20 0.91 72.92 248.75 3.99 103.89 45.95
Mix #4 P.M. E 25 #5 Comp 75 2.68 0.29 5.64 0.16 0.56 58.53 152.77 5.95 138.88 44.64
Mix #5 P.M. A 60 #4 Comp 40 2.45 0.22 4.47 0.29 0.81 81.26 147.67 4.95 99.10 33.69
Mix #6 P.M. A 25 #4 Comp 75 2.95 0.26 5.52 0.22 0.54 69.58 102.38 4.97 139.16 31.80
Mix #7 P.M. E 60 #4 Comp 40 2.74 0.28 4.11 0.23 0.79 78.00 141.00 5.00 83.00 30.00
Mix #8 P.M. E 25 #4 Comp 75 2.01 0.18 5.03 0.21 0.57 77.00 168.00 5.00 74.00 34.00

Table 10. Mineral Nutrient Content of Roots of Clematis Grown in the Various Media

Media % N % P % K % Mg % Ca ppm Zn ppm Mn ppm Cu ppm Fe ppm B
Peat Medium A 1.36 0.17 1.10 0.31 0.34 71.35 162.53 3.96 188.30 21.80
Peat Medium E 1.34 0.37 0.93 0.28 0.35 119.52 411.35 3.98 308.76 20.91
Compost #4 2.40 0.32 2.22 0.34 0.38 137.04 713.00 7.94 295.92 33.76
Compost #5 2.25 0.35 2.27 0.33 0.35 125.87 514.48 8.99 349.65 27.97
Mix #1 P.M. A 60 #5 Comp 40 1.41 0.18 1.93 0.29 0.36 91.90 299.70 4.99 353.64 23.97
Mix #2 P.M. A 25 #5 Comp 75 2.25 0.34 1.90 0.36 0.38 148.00 871.00 8.00 454.00 30.00
Mix #3 P.M. E 60 #5 Comp 40 1.38 0.24 1.58 0.28 0.36 91.72 242.27 4.98 336.98 22.93
Mix #4 P.M. E 25 #5 Comp 75 2.50 0.32 2.19 0.33 0.43 151.24 432.83 7.96 367.16 30.84
Mix #5 P.M. A 60 #4 Comp 40 2.14 0.41 2.09 0.33 0.41 160.51 232.30 8.97 375.87 23.92
Mix #6 P.M. A 25 #4 Comp 75 2.42 0.39 2.24 0.36 0.81 254.49 256.48 10.97 581.83 28.94
Mix #7 P.M. E 60 #4 Comp 40 2.27 0.50 2.11 0.35 0.57 142.99 227.40 9.93 506.45 25.81
Mix #8 P.M. E 25 #4 Comp 75 2.18 0.36 2.35 0.29 0.42 140.57 306.08 9.97 433.69 22.93

Table 11. Properties of the Total Greenhouse Media After Growth of Clematis for Ninety Days

Media Dry Matter % Moisture % On Dry Matter Basis
% Organic Matter % Organic Carbon % Total Nitrogen % Total Phosphorus % Total Potassium C/N Ratio
Peat Medium A 26.53 73.46 66.00 33.00 0.65 0.05 0.23 50.77
Peat Medium E 34.65 65.35 74.60 37.30 0.92 0.09 0.10 40.54
Compost #4 43.68 56.31 49.10 24.60 1.75 0.26 0.81 14.06
Compost #5 36.83 63.17 72.10 36.10 1.94 0.48 0.73 18.61
Mix #1 P.M. A 60 #5 Comp 40 38.55 61.44 53.20 26.60 1.40 0.22 0.52 19.00
Mix #2 P.M. A 25 #5 Comp 75 36.47 63.52 49.20 24.60 1.63 0.27 0.77 15.09
Mix #3 P.M. E 60 #5 Comp 40 46.84 53.16 59.00 29.50 1.37 0.19 0.52 21.53
Mix #4 P.M. E 25 #5 Comp 75 44.07 55.92 53.20 26.60 1.62 0.26 0.69 16.42
Mix #5 P.M. A 60 #4 Comp 40 32.91 67.08 65.80 32.90 1.74 0.43 0.43 18.91
Mix #6 P.M. A 25 #4 Comp 75 32.76 67.23 64.70 32.40 2.21 0.57 0.60 14.66
Mix #7 P.M. E 60 #4 Comp 40 31.18 68.81 70.60 35.30 1.62 0.33 0.37 21.79
Mix #8 P.M. E 25 #4 Comp 75 43.58 56.41 67.00 33.50 2.16 0.57 0.66 15.51

Table 12. Properties of the Greenhouse Media Extracts After Growth of Clematis for Ninety Days

Media pH NO-3ppm Ca ppm P ppm K ppm Mg ppm Total Salts MMhos/cm
Peat Medium A 7.20 11.01 24.01 2.01 28.01 9.01 0.39
Peat Medium E 6.70 2.01 37.01 13.01 42.01 6.01 0.45
Compost #4 7.70 33.01 232.01 2.01 877.01 84.01 4.79
Compost #5 7.91 8.01 85.01 19.01 540.01 29.01 2.82
Mix #1 P.M. A 60 #5 Comp 40 7.70 31.01 95.01 2.01 385.01 36.01 2.44
Mix #2 P.M. A 25 #5 Comp 75 7.70 63.01 179.01 3.01 817.01 69.01 4.52
Mix #3 P.M. E 60 #5 Comp 40 7.51 11.01 106.01 5.01 398.01 30.01 2.51
Mix #4 P.M. E 25 #5 Comp 75 7.70 25.01 162.01 3.01 665.01 54.01 3.85
Mix #5 P.M. A 60 #4 Comp 40 7.51 45.01 66.01 15.01 300.01 27.01 2.06
Mix #6 P.M. A 25 #4 Comp 75 7.60 67.01 89.01 21.01 468.01 35.01 2.68
Mix #7 P.M. E 60 #4 Comp 40 6.91 68.01 78.01 30.01 264.01 22.01 1.67
Mix #8 P.M. E 25 #4 Comp 75 7.51 50.01 77.01 21.01 462.01 25.01 2.72
Optimum Range 5.5-7.0 100-200 200-300 6.0-9.0 150-250 70-200 2.0-3.5

Table 13. Growth of Mums (Mean ± SEM, n = 3)

Media Day Zero (20/12) At 22 days (11/1) At 37 days (26/1) At 51 days (9/2)
Height cm # of Leaves Height cm # of Leaves Height cm # of Leaves Height cm # of Leaves
Peat Medium A 6.8 ± 0.3 8 ± 0 7.6 ± 0.0 14 ± 0 11.0 ± 0.3 24 ± 2 16.3 ± 0.4 28 ± 3
Peat Medium E 6.3 ± 0.0 7 ± 0 6.3 ± 0.0 13 ± 0 8.9 ± 1.0 20 ± 0 14.2 ± 1.2 21 ± 0
Compost #4 6.3 ± 0.0 8 ± 0 6.3 ± 0.0 11 ± 0 8.0 ± 0.3 20 ± 0 11.2 ± 0.0 21 ± 0
Compost #5 5.9 ± 0.3 7 ± 0 6.3 ± 0.0 10 ± 1 7.6 ± 1.0 19 ± 1 10.2 ± 0.6 19 ± 1
Mix #1 P.M. A 60 #5 Comp 40 7.6 ± 0.0 8 ± 0 8.0 ± 0.3 14 ± 0 9.1 ± 0.6 19 ± 1 12.1 ± 0.3 20 ± 1
Mix #2 P.M. A 25 #5 Comp 75 6.3 ± 0.0 7 ± 0 6.3 ± 0.0 11 ± 1 6.8 ± 0.3 17 ± 1 9.3 ± 0.1 18 ± 1
Mix #3 P.M. E 60 #5 Comp 40 5.7 ± 0.4 6 ± 1 6.3 ± 0.0 11 ± 0 6.8 ± 0.3 18 ± 1 9.1 ± 0.4 19 ± 1
Mix #4 P.M. E 25 #5 Comp 75 5.9 ± 0.3 8 ± 0 6.3 ± 0.6 13 ± 1 8.0 ± 0.9 21 ± 1 10.6 ± 0.9 21 ± 1
Mix #5 P.M. A 60 #4 Comp 40 5.9 ± 0.3 7 ± 1 6.4 ± 0.6 13 ± 1 8.9 ± 0.6 21 ± 1 13.1 ± 0.7 23 ± 1
Mix #6 P.M. A 25 #4 Comp 75 6.8 ± 0.3 7 ± 1 6.8 ± 0.3 13 ± 1 8.7 ± 0.5 21 ± 1 12.1 ± 0.3 22 ± 1
Mix #7 P.M. E 60 #4 Comp 40 5.9 ± 0.3 8 ± 0 6.4 ± 0.0 12 ± 1 8.0 ± 0.3 18 ± 1 11.0 ± 0.7 22 ± 1
Mix #8 P.M. E 25 #4 Comp 75 5.9 ± 0.3 7 ± 0 5.9 ± 0.3 11 ± 1 8.9 ± 0.6 20 ± 0 11.6 ± 0.6 21 ± 0

Table 14. Yield of Mums Plant Material (Mean ± SEM; n=3), g/pot

Media Weight of Cutting Fresh Weight of Plant Top Fresh Weight of Root Top Growth Top Growth as % of that on Peat Med. A Top Growth as % of that on Peat Med. E
Peat Medium A 4.83 ± 0.37 18.27 ± 0.64 6.20 ± 0.35 13.43 ± 0.94 100.0 176.0
Peat Medium E 4.73 ± 0.23 12.37 ± 2.24 4.67 ± 0.34 7.63 ± 2.15 56.8 100.0
Compost #4 4.1 ± 0.15 11.07 ± 1.03 3.1 ± 0.40 6.97 ± 0.92 51.9 91.3
Compost #5 3.6 ± 0.26 8.33 ± 0.51 2.87 ± 0.09 3.80 ± 0.62 28.3 49.8
Mix #1 P.M. A 60 #5 Comp 40 4.57 ± 0.37 11.37 ± 0.38 3.87 ± 0.30 6.80 ± 0.59 50.6 89.1
Mix #2 P.M. A 25 #5 Comp 75 3.87 ± 0.41 7.13 ± 0.52 2.77 ± 0.23 3.27 ± 0.49 24.3 42.9
Mix #3 P.M. E 60 #5 Comp 40 4.33 ± 0.64 7.40 ± 0.96 4.13 ± 0.52 3.07 ± 0.32 22.9 40.2
Mix #4 P.M. E 25 #5 Comp 75 4.87 ± 0.38 10.1 ± 0.90 3.53 ± 0.47 5.23 ± 0.60 38.9 68.5
Mix #5 P.M. A 60 #4 Comp 40 4.00 ± 0.75 15.93 ± 2.64 3.83 ± 0.48 11.93 ± 2.19 88.8 156.3
Mix #6 P.M. A 25 #4 Comp 75 3.87 ± 0.62 15.23 ± 0.91 3.03 ± 0.41 11.37 ± 1.58 84.7 149.0
Mix #7 P.M. E 60 #4 Comp 40 3.60 ± 0.50 16.4 ± 0.62 3.70 ± 0.31 12.80 ± 0.93 95.3 167.8
Mix #8 P.M. E 25 #4 Comp 75 4.00 ± 0.50 14.7 ± 1.31 3.00 ± 0.09 10.73 ± 1.56 79.9 140.6

Table 15. Mineral Nutrient Contents of Tops (stem + leaves + flowers) of Mums Grown on the Various Media (on dry matter basis)

Media % N % P % K % Mg % Ca ppm Zn ppm Mn ppm Cu ppm Fe ppm B
Peat Medium A 2.28 0.29 4.37 0.40 1.20 88.20 60.45 4.95 191.27 30.72
Peat Medium E 2.03 0.76 3.99 0.26 1.28 76.84 94.81 10.97 139.72 35.92
Compost #4 2.54 0.40 6.53 0.28 0.71 101.39 33.79 7.95 202.78 36.77
Compost #5 2.82 0.28 5.65 0.30 0.86 94.62 35.85 14.94 263.94 54.78
Mix #1 P.M. A 60 #5 Comp 40 2.92 0.36 4.98 0.27 0.95 92.90 36.96 10.98 416.58 38.96
Mix #2 P.M. A 25 #5 Comp 75 3.02 0.32 5.92 0.30 0.91 91.36 44.68 17.87 384.30 42.70
Mix #3 P.M. E 60 #5 Comp 40 2.56 0.60 4.93 0.30 1.21 176.47 108.67 411.76* 608.17 43.86
Mix #4 P.M. E 25 #5 Comp 75 3.04 0.46 5.96 0.33 1.02 116.76 47.90 11.97 402.19 43.91
Mix #5 P.M. A 60 #4 Comp 40 2.98 0.57 5.74 0.34 0.89 167.66 62.89 186.62* 471.05 35.92
Mix #6 P.M. A 25 #4 Comp 75 3.66 0.55 6.85 0.32 0.77 156.59 39.64 14.86 181.36 37.66
Mix #7 P.M. E 60 #4 Comp 40 3.69 0.74 6.04 0.29 0.99 168.49 48.85 11.96 239.28 38.88
Mix #8 P.M. E 25 #4 Comp 75 3.44 0.57 7.28 0.28 0.77 156.84 50.94 18.98 147.85 38.96

*Disregard as procedural error

Table 16. Mineral Nutrient Contents of Roots of Mums Grown in the Various Media

Media % N % P % K % Mg % Ca ppm Zn ppm Mn ppm Cu ppm Fe ppm B
Peat Medium A 1.89 0.30 3.90 0.30 0.51 45.45 24.24 18.93 220.45 7.57
Peat Medium E 1.41 1.12 4.59 0.22 0.47 63.96 42.34 19.81 215.31 7.20
Compost #4 1.94 0.43 6.12 0.43 0.43 54.93 28.91 29.87 423.13 10.60
Compost #5 2.80 0.23 6.37 0.31 0.46 56.39 22.97 21.93 465.79 21.93
Mix #1 P.M. A 60 #5 Comp 40 2.70 0.40 5.46 0.30 0.57 59.85 26.60 19.00 487.41 13.30
Mix #2 P.M. A 25 #5 Comp 75 2.59 0.37 5.08 0.21 0.43 51.89 25.94 17.29 534.05 8.64
Mix #3 P.M. E 60 #5 Comp 40 1.54 0.55 5.12 0.25 0.50 53.26 27.13 32.16 333.66 12.06
Mix #4 P.M. E 25 #5 Comp 75 2.64 0.45 5.90 0.28 0.51 48.86 31.81 44.31 496.59 18.18
Mix #5 P.M. A 60 #4 Comp 40 2.72 0.91 5.08 0.24 0.45 69.18 15.13 23.78 310.27 7.56
Mix #6 P.M. A 25 #4 Comp 75 3.91 0.93 5.75 0.25 0.50 98.75 42.50 151.25 507.50 10.00
Mix #7 P.M. E 60 #4 Comp 40 3.20 3.20 4.53 0.13 0.44 58.66 12.44 16.00 284.44 3.53
Mix #8 P.M. E 25 #4 Comp 75 3.75 1.00 6.31 0.21 0.43 60.00 23.75 38.75 332.50 8.75

Table 17. Properties of the Total Medium after Growth of Mums for Seventy-Seven Days

Media Dry Matter % Moistur e % On Dry Matter Basis
% Organic Matter % Organic Carbon % Total Nitrogen % Total Phosphor us % Total Potassium C/N Ratio
Peat Medium A 28.50 71.49 66.22 33.11 0.64 0.06 0.18 51.73
Peat Medium E 34.84 65.16 76.76 38.38 0.92 0.09 0.08 41.72
Compost #4 34.20 65.79 70.66 35.33 2.25 0.58 0.73 15.70
Compost #5 43.11 56.88 49.55 24.78 1.82 0.27 0.86 13.62
Mix #1 P.M. A 60 #5 Comp 40 32.36 67.63 52.90 26.45 1.47 0.20 0.51 17.99
Mix #2 P.M. A 25 #5 Comp 75 35.85 64.14 49.03 24.51 1.78 0.26 0.78 13.77
Mix #3 P.M. E 60 #5 Comp 40 35.41 64.58 60.29 30.14 1.50 0.23 0.48 20.09
Mix #4 P.M. E 25 #5 Comp 75 35.83 64.16 52.07 26.04 1.76 0.26 0.75 14.80
Mix #5 P.M. A 60 #4 Comp 40 28.81 71.18 65.00 32.50 1.88 0.42 0.38 17.29
Mix #6 P.M. A 25 #4 Comp 75 29.20 70.79 64.96 32.48 2.44 0.61 0.67 13.31
Mix #7 P.M. E 60 #4 Comp 40 30.60 69.39 71.45 35.72 1.69 0.38 0.39 21.14
Mix #8 P.M. E 25 #4 Comp 75 29.56 70.43 69.41 34.71 2.35 0.54 0.73 14.77

Table 18. Properties of the Media Extracts after Growth of Mums for Seventy-Seven Days (greenhouse media analysis)

Media pH NO3-N ppm Ca ppm P ppm K ppm Mg ppm Total Salts MMhos/cm
Peat Medium A 7.10 5.01 35.01 1.01 9.01 16.01 0.47
Peat Medium E 6.70 3.01 40.01 16.01 27.01 7.01 0.44
Compost #4 8.01 19.01 106.01 16.01 671.01 37.01 3.67
Compost #5 7.91 22.01 282.01 2.01 1147.01M 104.01 6.12
Mix #1 P.M. A 60 #5 Comp 40 7.91 27.01 93.01 3.01 407.01 35.01 2.41
Mix #2 P.M. A 25 #5 Comp 75 7.81 55.01 164.01 3.01 760.01 63.01 3.61
Mix #3 P.M. E 60 #5 Comp 40 7.51 12.01 102.01 5.01 381.01 28.01 2.29
Mix #4 P.M. E 25 #5 Comp 75 7.60 59.01 199.01 4.01 810.01 68.01 4.68
Mix #5 P.M. A 60 #4 Comp 40 7.60 17.01 59.01 15.01 268.01 23.01 1.77
Mix #6 P.M. A 25 #4 Comp 75 7.41 87.01 102.01 20.1 444.01 38.01 2.69
Mix #7 P.M. E 60 #4 Comp 40 7.01 48.01 71.01 24.01 250.01 20.01 1.87
Mix #8 P.M. E 25 #4 Comp 75 7.31 69.01 95.01 22.01 517.01 31.01 2.56
Optimum Range 5.50-7.00 100-220 200-300 6.0-9.0 1.50-2.50 70-200 2.0-3.5

Table 19. pH Values at the Beginning and End of Plant Growth, and Changes

Media Initial After Clematis Growth Change After Mums Growth Change
Peat Medium A 6.20 7.20 +1.0 7.10 +0.90
Peat Medium E 6.01 6.70 +0.69 6.70 +0.69
Compost #4 8.01 7.70 -0.31 8.01 +0.00
Compost #5 7.51 7.91 +0.41 7.91 +0.40
Mix #1 P.M. A 60 #5 Comp 40 7.60 7.70 +0.10 7.91 +0.31
Mix #2 P.M. A 25 #5 Comp 75 8.01 7.70 -0.31 7.81 -0.20
Mix #3 P.M. E 60 #5 Comp 40 7.20 7.51 +0.31 7.51 +0.31
Mix #4 P.M. E 25 #5 Comp 75 7.70 7.70 0.00 7.60 -0.10
Mix #5 P.M. A 60 #4 Comp 40 7.60 7.51 -0.09 7.60 0.00
Mix #6 P.M. A 25 #4 Comp 75 8.20 7.60 -0.60 7.41 -0.79
Mix #7 P.M. E 60 #4 Comp 40 7.01 6.91 -0.1 7.01 0.00
Mix #8 P.M. E 25 #4 Comp 75 7.91 7.51 -0.40 7.31 -0.60

Last Modified: Wednesday December 15 2004