QLK5-2000-00044 Biodegradable plastics for environmentally friendly mulching and low-tunnel cultivation

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Paints/Coatings/Plastics : Quality of Life - 5.2 Non-Food Development

Contract No:	QLK5-2000-00044
Source:	First Progress Report Summary - 2002
	Second Progress Report Summary - 2003

Second Progress Report Summary 2003

Introduction

The development of biodegradable films suitable for soil mulching and/or covering of low-tunnels could offer a solution to environmental problems related to direct cover cultivation. The efficient and profitable use of such biodegradable films aiming at reducing pollution in rural areas through practising environmentally friendly, sustainable agriculture, involves several crucial agronomic and technological questions. These relate to definition of specifications for the development of bioplastic films production and testing of new biodegradable films suitable for mulching and low-tunnel or direct cultivation as well as the evaluation of the performance of the new bioplastic films.

The overall aim of the project is to investigate all of the above mentioned aspects and to integrate them into well justified agricultural techniques using bioplastics for enhancing sustainable, environmentally friendly and economically optinised mulching, direct cover and low-tunnel cultivation in Europe:

Activities

Milestone 1 Environmental impact assessment of current mulching and low-tunnel practices in Europe as compared to the use of biodegradable materials. The results achieved in this area include an overview covering the classification and characteristics of biodegradable materials suitable for agricultural applications as films for low-tunnel and direct cover cultivation and mulching. This information is continually updated. In addition a systematic overview of existing mulching and low-tunnel practices in Europe has been completed. This includes an analysis of the advantages and possible problems expected from the extended use of biodegradable materials and an environmental impact assessment concerning the practices currently in use in low tunnel and direct cover protected cultivation and mulching. A preliminary environmental impact assessment of the proposed use of bioplastics has been completed.

Milestone 2 Design requirements of bioplastics related to a) microclimate, with respect to crop growth and yield; b) critical mechanical properties with respect to loading conditions and structural design of low-tunnel structures and to mechanised installation methods for low-tunnels, direct covers and mulching.

Milestone 3 Design requirements with respect to the biodegradation behaviour of bioplastics, defined in terms of selected agricultural applications, the time dependence of critical mechanical and physical properties of the material and requirements with respect to soil quality.

The range of microclimate and soil parameters sufficiently satisfying the plant needs for various crops suitable for direct covering or low tunnel cultivation has been defined. Microclimate related design requirements of bioplastic covers with respect to crop growth and the quantity and quality of the crop production have been established. In addition, the mechanical design requirements of bioplastic covers for designing low-tunnel structures and using mechanised installation methods for low-tunnels, direct covers and mulching have been determined.

The design requirements of bioplastic covers with respect to their biodegradation behaviour are under continuing investigation, as are the design requirements of bioplastic covers with respect to their environmental impact.

Milestone M4 Assessment of several types of bioplastics specifically for mulching and low-tunnels cultivation Several types of appropriate biodegradable materials for agricultural applications will be selected or improved and others will be produced. The behaviour of these materials will be assessed in terms of physical/agronomic and mechanical properties as well as biodegradability.

The development of new compounds and processing optimisation required for the production of new biodegradable plastic films with improved mechanical and functional characteristics is in progress. The evaluation of the biodegradability of various bioplastics, which could be used for mulching or as low tunnel and direct cover was found to follow closely the field experiments and the laboratory tests.

The results of the on-going evaluation of the mechanical properties are used as feedback for the material design and optimisation including the selection of the most suitable materials for use with laying machines. They are also investigated under various loading conditions in order to test them under full scale conditions. Likewise, the evaluation of the physical properties is in progress, as well as the evaluation of ecotoxicology.

Benefits and Beneficiaries

• Development of know-how by the industries for the production of optimised materials-products for the specific application
• in the long run, benefits are expected for the European environment and the farmers in terms of eliminating/minimising the relevant agricultural plastic wastes and related disposal problems, requirements and cost.

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First Progress Report Summary 2002

Introduction

There is an increasing interest in the use of mulching and low-tunnels for protected cultivation. The market of plastics used for these purposes in Europe involves hundreds of thousands of ha and thousands of tons of plastic films per year. A large portion of these is left on the field or burnt uncontrollably by the farmers releasing harmful substances with the associated obvious negative consequences to the environment. The reasons for these environmentally dangerous practices are the lack of cost efficient systematic disposal techniques available to the growers and the high labour cost for the proper collection of the plastic films following the end of the cultivation period. Thus, the use of biodegradable materials appears as a challenging attractive alternative for enhancing sustainable and environmental friendly agricultural activities in mulching and low-tunnels cultivation.

The development of biodegradable films suitable for soil mulching and/or covering of low-tunnels could offer a solution to environmental problems related to direct cover cultivation. The efficient and profitable use of such biodegradable films aiming at reducing pollution in rural areas through practising environmentally friendly, sustainable, agriculture, involves several crucial agronomic and technological questions to be addressed through the present project. These include:

Definition of specifications for the bioplastic films to be developed based on requirements imposed by:

• Crop needs in terms of microclimate conditions
• Existing agronomic practices and agricultural machinery in use
• Local conditions concerning loads on low-tunnels and mulching covers
• Environmental impact aspects

Development, production arid testing of new biodegradable films suitable for mulching and low-tunnel or direct cultivation. The new bioplastic materials should:

• provide optimal mechanical and physical properties suitable for protected cultivation
• release no harmful to the man and/or to the environment substances during the biodegradation process.

Evaluation of the performance of bioplastic films by:

• Measuring the biodegradability and correlating the results of standard laboratory degradation tests to those of fill-scale field tests.
• Characterising the bioplastic films with respect to radiometric and other physical properties relevant to crop growth and yield
• Characterising the bioplastic films with respect to the mechanical properties related to specific mechanical performance requirements.
• Investigating the impact of the degradation of bioplastics to the environment, especially to the soil quality, including possible ecotoxicity effects.

Objectives

The overall objective of the project is to investigate all of the above mentioned aspects and to integrate them into well justified agricultural techniques using bioplastics for enhancing sustainable, environmentally friendly and economically optimised mulching, direct cover and low-tunnel cultivation in Europe. In particular, the specific objectives of the project are

• To present systematically available bioplastics and obtain a better knowledge of their behavior with respect to biodegradability; establish characterization methods.
• To determine the suitability and the requirements (specifications) of bioplastics to be used for direct soil cover, mulching and low-tunnel cultivation, such as those of strawberry and lettuce.
• To develop new biodegradable fl/ins (bioplastics) with improved properties suitable to mulching, direct cover and low-tunnel cultivation
• To evaluate the agronomically important physical properties, the mechanical properties and the degree and rate of biodegradation and environmental-ecotoxicological impact of selected commercially available and newly developed biodegradable materials (e.g. starch based, polyesters, etc.) using various laboratory tests.
• To develop new environmentally friendly mulching and low-tunnel cultivation techniques by using biodegradable plastic films. The development of such well justified horticultural methods based on novel biodegradable materials will promote sustainability, reduce the contamination of soil and enhance the protection of the landscape in rural areas against aesthetic pollution.
• To determine the overall physical performance with respect to crop production, the mechanical performance and the degree and rate of real-time biodegradation" and environmental impact-ecotoxicity of selected biodegradable materials by performing real cultivation experiments.
• Biodegradation data obtained from standard laboratory tests will be correlated to data from real biodegradation experiments where the impact on soil-environment and the agricultural production will also be evaluated
• To develop guidelines for using bioplastics in direct cover and low-tunnel cultivation and soil mulching (methodology and regulations).

Deliverables

The above objectives will result in the following main deliverables:

• Definition of requirements for biodegradable films to be used in low-cover, protected cultivation for crops of high economic importance for Europe, and soil mulching.
• Development of new bioplastic films (prototypes) according to the above requirements with respect to their functionality, biodegrability, and environmental impact.
• Development of guidelines for the proper, environmental fliendly use of biodegradable films in low-cover protected cultivation and mulching.

Activities

The technical work to be carried out under this project is broken down into four work packages:

Work package 01 can be considered as a prerequisite-preliminary step with the intention of mapping the current situation in the production of bioplastics for agricultural applications. For this reason, the available bioplastics and the typical agricultural practices involving the use of plastic films as low-tunnel, mulching or direct covers, will he systematically recorded. Moreover, the environmental impact of protected cultivation practiecs will be evaluated. In this way, important inventories will be generated, which will support the decision making throughout the project.

Work package 02 aims at defining agronomic and technical requirements for biodegradable films to be used as covering material in protected cultivation. Specific applications (low-tunnels, direct cover, mulching) will be analysed in terms of functional requirements of the cover such as loading and microclimate conditions. Finally requirements concerning the degree and rate of biodegradation as well as environmental impact and ecotoxicity related requirements of bioplastics used in protected cultivation will be decided. The definition of the requirements is a prerequisite for the development of new biodegradable films to be used as covers in low protected cultivation and soil mulching.

Work package 03 concerns the development and production of improved new bioplastics meeting the requirements set through the work package WP 2. The new materials will be tested systematicaIly against-the set requirements. Various testing methods will be employed, measuring relevant chemical, mechanical, and physical properties characterising the performance of the bioplastics as cover. Moreover, the biodegrability of the new material, as well as the environmental impact and ecotoxicity of their biodegradation will be investigated realising that their performance can only be fully analysed by field experiments, where the films will be used for typical crop production.

Work-package 04 is devoted to extensive experimental cultivation using the biodegradable materials developed under WP 3. The field experiments will take place under various climatic and soil conditions in order to fully investigate the behaviour of the films throughout Europe.

Progress during the first reporting period

WP1 has been accomplished and the results provided the consortium with a useful overview of the current situation in the production of bioplastics for agricultural applications. More specifically, the available bioplastics and the typical agricultural practices involving the use of plastic films as low-tunnel, mulching or direct covers, have systematically been recorded. Moreover, the environmental impact of protected cultivation practices has been evaluated. This has resulted in a database describing the available bioplastics.

Mulching and low-tunnel or direct-cover films are used extensively in modern agriculture. The quantities of plastics used in these applications together with a short description of the most important crops grown under low covers and the corresponding cultivation techniques have been collected and used for selecting typical crops for the field experiments performed under WP 4. The cultivation techniques for these selected crops have been described.

A report concerning the environmental impact of the extensive use of conventional (PE) mulching and low-cover films in agriculture has been prepared. The results will be used for evaluating the environmental advantages of using biodegradable films.

WP2 is in progress. A report has been prepared concerning the microclimate requirements for the selected crops to be grown. Two other tasks concerning the modelling of microclimate under low covers and mulching and the load requirements for the films are in progress. Other tasks are planned to begin during the second year of the project. The microclimate requirements concerning the cultivation of melons, watermelons, strawberries, lettuce and cucumbers have been investigated in detail. The first three crops concern production in S. Europe, while the other two are crops grown under cover in N. Europe. Further information has been obtained concerning cultivation of pepper, eggplant and courgette.

A model describing the microclimate under cover has been proposed. It will be calibrated and validated by measurements to be performed during the second year. The requirements for load tunnels and mulching have been calculated based on existing Standards and Codes of Practice. However, the validity and possible adaptations of the methodologies proposed by these codes in the case of low-tunnels have to be further explored. For this reason, experiments will be performed during the second year.

WP3 concerns the development and production of improved new bioplastics. During the first year of the project, two new materials have been prepared and used for the production of a variety of mulching and low-cover films. The new materials have been tested systematically with respect to relevant chemical. mechanical, and physical properties characterising the performance of the bioplastics as cover. Further, the biodegrability of the new material, as well as the environmental impact and ecotoxicity of their biodegradation is under investigation.

Protocols have been prepared for performing laboratory and field experiments for testing biodegradability. Experiments are already in progress or planned to start during the second year of the project. The mechanical behaviour of the original materials has been tested. Measurements of the mechanical properties of the exposed (used) materials are in progress as are measurements of radiometric properties of the original materials. The sampling of both soil and compost samples for ecotoxicological evaluation from laboratory and field experiments is underway. The microbial biomass measurements have already started in the field conditions. A wide variety of ecotoxicity tests are being set up at different laboratories. One polymer has been tested with three different ecotoxicity tests in soil environment.

WP4 is devoted to extensive experimental cultivation using the biodegradable materials developed under WP 3. The field experiments will take place under various climatic and soil conditions in order to fully investigate the behaviour of the films throughout Europe. The first field experiment is in progress and is expected to conclude this summer. Detailed guidelines concerning the field experiments have been developed to describe in detail the cultivation method, the electronic monitoring of the microclimate and weather conditions, the sampling method and the tests to be performed throughout the experiment. This includes a special data logging system and sensors developed for the purposes of the present project.

Four field experiments for testing the performance of bioplastic films are in progress in four different European countries where typical local crops are grown. The experiments have different durations depending on the crop and conclude during summer 2002, when the first cultivation period ends. Tests of used materials are in progress. Visual inspection of the bioplastics and the crops take place regularly in order to monitoring their performance.