Short communication

National inventory of organic wastes for use as growing media forornamental potted plant production: case study in Spain

Manuel Abad a,*, Patricia Noguera a, Silvia Bur�es b

a Departamento de Producci�on Vegetal, Universidad Polit�ecnica de Valencia, P.O. Box 22012, E46071 Valencia, Spainb Direc-TS. C/Badal, 19-21, B entlo. 1, E-08014 Barcelona, Spain

Received 29 May 2000; received in revised form 15 September 2000; accepted 16 September 2000

Abstract

An inventory of materials suitable for use as growing media for ornamental potted plant production in Spain has been prepared.

Special attention has been paid to solid organic wastes generated by production, industrial and consumer activities. Information

obtained from this study has been organised into two data bases. Data base 1 contains the ``General Characteristics'' ®le of more

than 105 materials. In this ®le, data are available regarding generation points, material availability, uses, cost, disposal expenses, etc.

Data base 2 is comprised of the ``Speci®c Properties'' ®le of 63 materials selected from data base 1. The main physical, chemical and

biological properties of these materials as container media have been characterised, and the results obtained have been compiled.

Finally, a computerised data bank has been created which can be found in the home page of the Spanish Ministry of Agriculture,

Fisheries and Food (http://agritel2.mapya.es/sustratos/). Ó 2001 Elsevier Science Ltd. All rights reserved.

Keywords: Waste reclamation; Container media; Soilless potting media; Peat substitutes; Sustainable agriculture; Computerised data bank; Web page

1. Introduction

For some time Sphagnum peat has been the mostwidely used growing media constituent for the produc-tion of ornamental potted plants. However, since thelate 1970s there has been a worldwide search for newpeat substitutes (Raviv et al., 1986; Robertson, 1993).One reason for this is the high price of high qualityhorticultural peat, especially in countries without peatmoss resources. A second reason is the questionableavailability of peat in the near future due to environ-mental constraints.

Moreover, in an e�ort to recycle and reclaim solidwastes, various organic residues generated by agricul-ture, livestock farming, forestry, industries and citycentres are being successfully used as container mediafor ornamental plant production (Verdonck, 1988;Abad et al., 1997; Ingelmo et al., 1998). Thus, an in-crease in the demand for solid organic wastes has beengenerated, and so these materials are now considered asuseful and value-added products (Hauke et al., 1996;Bur�es, 1997).

Consequently, it seemed particularly advantageous tomake an inventory of materials in Spain which aresuitable for use as growing media for containerised or-namental plants. Countries such as Belgium, France andthe UK have already begun making partial inventoriesof materials suitable for this horticultural purpose (Cull,1981; Verdonck, 1984; Moinereau et al., 1987; Pryce,1991).

The objective of this research was to inventory ma-terials found in Spain which are suitable for use asgrowing media for ornamental potted plant production,the focus being on organic wastes generated by pro-duction, industrial and consumer activities.

2. Methods

Nine research teams distributed throughout the sev-enteen Spanish Autonomous Communities contributedto the study.

The research was carried out in three consecutivestages. First, a ®le was constructed including all thepotential materials and their general characteristics (i.e.location of material deposit or dump, annual productionand availability year round, current uses and possibleapplications, price, disposal costs, etc.). The channels

Bioresource Technology 77 (2001) 197±200

* Corresponding author. Tel.: +34-96-387 7336; fax: +34-96-387

7339.

E-mail address: mabad@prv.upv.es (M. Abad).

0960-8524/01/$ - see front matter Ó 2001 Elsevier Science Ltd. All rights reserved.

PII: S 0 9 6 0 - 8 5 2 4 ( 0 0 ) 0 0 1 5 2 - 8

used to acquire the information were: (a) direct mailingto private companies, public institutions, etc.; (b) per-sonal contacts with solid waste managers, governmento�cials, etc.; (c) literature survey of published data; and,(d) press releases and advertisements. After gatheringthis information, 63 materials were selected for theirsubsequent analysis.

In the second stage, the selected materials weresampled and their main physical, chemical and bio-logical properties were characterised. Physical proper-ties were determined in accordance with Gabri�els andVerdonck (1991) and Mart�inez (1992). The method ofwater suspension 1/6 (v/v) (British Standard, 1990) wasused to determine the pH and the electrical conduc-tivity. Total organic matter was determined accordingto Mart�inez (1992), and the analysis of heavy metalswas carried out following the standard CEE BCR No.144 (CEE ± Commission of the European Communi-ties, 1983). Finally, in the seed germination bioassays(Zucconi et al., 1981) a water extract of the materialwas obtained by ®ltering the suspension 1/10 (w/w),which was used as such and diluted with distilled water(1/3, v/v) (Abad et al., 1999). Once the properties of thematerials were characterised, a speci®c ®le was thencompiled.

The third stage consisted in creating and publicising ±via Internet ± a computerised data bank, which includedboth the general characterisation and the speci®c prop-erties ®les.

3. Results and discussion

A general characterisation ®le of 107 materials whichcan be used as growing media for the production ofornamental potted plants in Spain has been prepared.Special attention has been paid to wastes generated bydi�erent production, industrial and consumer activities.

The study speci®ed the current status of solid organicwastes inventoried throughout the seventeen SpanishAutonomous Communities. Information given includedgeneration points, quantities involved, seasonal ¯uctu-ations, current use as container media, other uses, price,disposal costs, and so on. With all this information adata base was created. It became apparent from theearly stages of the survey that information on wasteavailability was scarce since solid waste management isstill in its infancy in Spain. The sole exception is that ofurban residues, especially biowastes and biosolids. Toful®l study requirements, waste amounts were some-times estimated. Nevertheless, the information presentedis a good calculation of wastes generated in Spain withpotential use as container substrates.

The main properties of 63 materials selected from theaforementioned data base were characterised as con-tainer media. With the results obtained, a second database was created. This data base also included colourphotographs of each of the analysed materials.

Table 1 summarises the distribution of the materialsaccording to the optimum range of the physical, physi-co-chemical and chemical properties studied.

It was apparent that most of the wastes showedproperties which were either acceptable or easily im-provable, and therefore, these materials were evaluatedas viable and feasible peat substitutes.

Half of the samples exhibited a particle size aboveoptimum, which was re¯ected in a high air content to-gether with a low water-holding capacity. These resultsshow the need to shred, mill or sieve the materials toreduce the size of their particles and make irrigationeasier.

As far as heavy metals are concerned, all the mate-rials showed levels (data not shown) which were inferiorto the maximum allowed by Spanish regulations.

Table 2 shows the distribution of the materials atselected intervals of the cress and lettuce seed germina-

Table 1

Distribution (in percentage) of the 63 materials analysed according to the acceptable or optimum range of selected physical, physico-chemical and

chemical properties for container media

Property Acceptable/optimum rangea (R) % of materials with a value

Below R Within R Above R

Particle size 0.25±2.0 mmb 3 47 50

Bulk density < 0.4 g/cm3 ± 92 8

Particle density 1.4±2.0 g=cm3 2 90 8

Total pore space >85% vol 21 79 ±

Air capacity 20±30% vol 2 21 77

Water volume at 10 cm water tension 55±70% vol 94 6 0

Total water-holding capacity 600±1000 ml/l 98 2 0

Shrinkage < 30 % vol ± 78 22

pH 5.3±6.5 11 30 59

Electrical conductivity 6 0:5 dS=m ± 48 52

Total organic matter > 80% 46 54 ±

a According to Raviv et al. (1986), Bunt (1988), Abad et al. (1992) and Ansorena (1994).b Percentage by weight of particles with diameter between 0.25 and 2 mm.

198 M. Abad et al. / Bioresource Technology 77 (2001) 197±200

tion index (GI). The pure extract of 54% and 35% ofthe wastes showed a low GI, i.e. less than 60% of thecontrol, for cress and lettuce, respectively. In the lightof these results, some of the wastes studied will need tobe aged, composted, etc., in order to transform theminto mature and stable products, and hence, adequatefor use as growing media. When the pure extract wasdiluted, the GI increased remarkably, specially that ofcress.

Moreover, some materials showed a GI > 120%(Table 2), thus indicating a stimulating e�ect on thegermination of seeds and, probably, on the growth ofthe subsequent plant.

Finally, a computerised global and cross-referencedData Bank was created with the two aforementioneddata bases and installed in the Web site of the SpanishMinistry of Agriculture, Fisheries and Food at: http://agritel2.mapya.es/sustratos/. Currently this home page isonly in Spanish.

4. Conclusion

An inventory was prepared of materials suitable foruse as growing media for ornamental potted plant pro-duction in Spain, the focus being on solid organic wastesgenerated by production, industrial and consumer ac-tivities. Given that the price of high quality Sphagnumpeat continues to rise and its future availability is beingquestioned, the possibility of using waste products forthis end should be considered.

A data bank has been created which can be accessedvia the Internet by both manufacturers and consumersof container media. In order to continue with this study,data bank updating is crucial, modifying existing ®lesand removing or inserting new materials as needed.

Acknowledgements

This research has been subsidised by the SpanishInter-ministerial Commission for Science and Technol-ogy (CICYT) through the Special Project AGF 95-1698-E. The authors would like to thank the Spanish Ministry

of Agriculture, Fisheries and Food for its contributionto the study, and Debra Westall for her assistance in thetranslation and revision of this article.

References

Abad, M., Mart�inez, P.F., Mart�inez, M.D., Mart�inez, J., 1992.

Evaluaci�on agron�omica de los sustratos de cultivo. Actas de

Horticultura 11, 141±154.

Abad, M., Noguera, P., Noguera, V., Roig, A., Cegarra, J., Paredes,

C., 1997. Reciclado de residuos org�anicos y su aprovechamiento

como sustratos de cultivo. Actas de Horticultura 19, 92±109.

Abad, M., Bur�es, S., Noguera, P., Carbonell, S., 1999. Resultados de la

Acci�on Especial CICYT ``Elaboraci�on de un inventario de sustra-

tos y materiales adecuados para ser utilizados como sustratos o

componentes de sustratos en Espa~na''. Actas de Horticultura 23,

45±61.

Ansorena, J., 1994. Sustratos. Propiedades y Caracterizaci�on. Edici-

ones Mundi-Prensa, Madrid.

British Standard, 1990. Recommendations for Peat for Horticultural

and Landscape Use, BS 4156. British Standards Institution,

London.

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

second ed. Unwin Hyman Ltd., London.

Bur�es, S., 1997. Sustratos. Ediciones Agrot�ecnicas S.L., Madrid.

CEE - Commission of the European Communities, 1983. The

Certi®cation of the Contents (mass fractions) of Cadmium, Cobalt,

Copper, Manganese, Mercury, Nickel, Lead and Zinc in a Sewage

Sludge of Domestic Origin. BCR No. 144. EUR 8836 EN. CEE ±

Community Bureau of Reference, BCR Information.

Cull, D.C., 1981. Alternatives to peat as container media: Organic

resources in the UK. Acta Horticulturae 126, 69±81.

Gabri�els, R., Verdonck, O., 1991. Physical and chemical characteriza-

tion of plant substrates: Towards an European standardization.

Acta Horticulturae 294, 249±259.

Hauke, H., St�oppler-Zimmer, H., Gottschall, R., 1996. Development

of compost products. In: de Bertoldi, M., Sequi, P., Lemmes, B.,

Papi, T. (Eds.), The Science of Composting: Part 1. Blackie

Academic & Professional, Glasgow, pp. 477±494.

Ingelmo, F., Canet, R., Ib�a~nez, M.A., Pomares, F., Garc�ia, J., 1998.

Use of MSW compost, dried sewage sludge and other wastes as

partial substitutes for peat and soil. Bioresource Technology 63,

123±129.

Mart�inez, F.X., 1992. Propuesta de metodolog�ia para la determinaci�on

de las propiedades f�isicas de los sustratos. Actas de Horticultura

11, 55±66.

Moinereau, J., Herrmann, P., Favrot, J.C., Rivi�ere, L.M., 1987. Les

substrats-Inventaire, caract�eristiques, ressources. In: Blanc, D.

(Dir.), Les Cultures Hors Sol. 2e �ed. Institut National de la

Recherche Agronomique (INRA), Paris, pp. 15±77.

Pryce, S., 1991. The Peat Alternatives Manual. Friends of the Earth,

London.

Table 2

Distribution (in percentage) of the 63 materials analysed at selected intervals of the cress and lettuce seed GI of water extracts

Seed Extract GI, % of control

< 60 60±80 81±120 > 120

Cress Pure 54 16 28 2

Diluteda 22 19 54 5

Lettuce Pure 35 18 33 14

Diluteda 13 13 60 14

a With distilled water (1/3, v/v).

M. Abad et al. / Bioresource Technology 77 (2001) 197±200 199

Raviv, M., Chen, Y., Inbar, Y., 1986. Peat and peat substitutes as

growth media for container-grown plants. In: Chen, Y., Avnime-

lech, Y. (Eds.), The Role of Organic Matter in Modern Agricul-

ture. Martinus Nijho� Publishers, Dordrecht, The Netherlands, pp.

257±287.

Robertson, R.A., 1993. Peat, horticulture and the environment.

Biodiversity and Conservation 2, 541±547.

Verdonck, O., 1984. Reviewing and evaluation of new materials used

as substrates. Acta Horticulturae 150, 467±473.

Verdonck, O., 1988. Composts from organic waste materials as

substitutes for the usual horticultural substrates. Biological Wastes

26, 325±330.

Zucconi, F., Pera, A., Forte, M., de Bertoldi, M., 1981. Evaluating

toxicity of immature compost. BioCycle 22, 54±57.

200 M. Abad et al. / Bioresource Technology 77 (2001) 197±200