Photodegradable plastics in agriculture

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. 

Degradable Polymers. Edited by Gerald Scott and Dan Gilead. 

This is a formidable list, although by no means complete. Extra benefits are derived from a combination of the afore-mentioned actions. The prevention of the drying-out of the top soil between irrigations or precipitations, which occurs with bare ground, creates ideal conditions for the root system to develop laterally rather than vertically. Such root development is very desirable as it occurs in the top soil where ideal growing conditions are obtained warmth and the presence of beneficial microorganisms which increase the availability of nutrients to the plants. In turn less fertilization is required which is economically desirable [6]. 

The continuous use of nitrogenous fertilizers, which are eventually leached into the ground water and drained into the rivers and lakes, is the main cause of the damage done to the aquatic flora and fauna in all agricultural regions where intensive farming is practised. A cautionary example is the dying of the Aral Sea which now needs costly and extensive action if it is to be saved. 

All summer crops such as melons, watermelons, sunflowers, cotton, maize, etc. require a minimum soil temperature for the germination of seeds. Soil covered with plastic will heat up earlier through the greenhouse effect. The pillow of air that is created between the film and the soil insulates the crop from the low outside temperatures during the night and from the convecting effects of cold winds. 

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Gilead, D., 1995, Photodegradable Plastics in Agriculture. In Degradable Polymers Principles and Applications (G. Scott and D. Gilead, eds). Chapman Hall, London, pp. 186-199. 

Gilead, D. Photodegradable plastics in agriculture. In Scott, G., Gilead, D. (eds.) Degradable polymers, p. 186. Springer, Amsterdam (1995)... 

Gilead D (1995) Photodegradable Plastics in Agriculture in Scott G and Gilead D, eds., Degradable Polymers Principles and Application, I edition, Chapman Hall (Kluwer Acad. Pub.), Chapter 10. 

On the more commercial front, the photooxidation of polymers continues to attract attention with a continued special interest in natural materials. Bio- and photodegradable plastics are important for agricultural usage. The same applies to polymer stabilisation where commercial applications dominate significantly with much emphasis on the synergistic behaviour of stabilisers. For dyes and pigments stability continues to be of major concern. 

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