The disposal of mulching films after use

The great bulk of soiled plastic films left at the head of the field will soon accumulate to unmanageable quantities, since burning of the material is not allowed in most countries. Moreover, this is not an efficient method as the burning plastic melts, chars and becomes a block of material that will resist all further handling. Transportation to landfills is costly and the lack of landfill facilities generally precludes the burial of the waste material. 

It has become clear that in the case of mulching films controlled self-destruction is the perfect solution. Not only does it present an economical alternative to manual collection and ultimate disposal, but it allows the utilization of mulching films with crops which cannot be grown with regular plastic films. 

Stand % Early crop Total crop Markelabte yield 

The Scott-Gilead systems, the scientific principles of which are dealt with in other parts of this book, satisfy the requirements for degradability and have found wide application in agriculture [20]. 

In fields where non-degradable plastic mulch has been used, there is always a sizeable residue of uncollected films which remains for a long time even 

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Gilead D (1995) The disposal of mulching films after use. In Scott G, Gilead D (eds) Degradable polymers principles and applications. Chapman Hall, London, chap 10... 

The wide application of plastics in agriculture has a decisive influence on cultivation practices. Plastic films used as a growing aid in the form of mulch and tunnel covers have increased yields. The debris of these films left behind after the harvest poses a serious disposal problem. The controlled photodegradation of plastics affords a workable solution not only to this problem but opens new possibilities of the programmed removal of the films even during the growing period of the crops when this is desirable. 

The use of plastic mulch, however, causes serious problems due to the need to dispose of the plastic debris after the harvest. At the end of the cultivation cycle the plastic film must be in good condition so that it can be picked up without too much difficulty by manual or mechanical operations. That is, provided the type and nature of the crops allows such a removal. The costs of the removal are not only in the actual time and labour spent, but also in the need to impart sufficient mechanical strength to the film by using high-quality raw materials and thickness gauges of at least 30 pm. This last requirement translates into the use of 250-400 kg of plastic film per hectare, depending on the type of crops. Once the cultivation cycle is finished and the films have been removed from the field there still remains the final disposal of the collected plastic. This can be handled in different ways. 

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