Forty per cent of the carrot crop is harvested from the field between January and May using black plastic covers and a straw layer to stop frost damage and spring regrowth.
Estimates for annual tonnages (including soil contamination) requiring disposal are 10,000 tonnes for carrots and 1,230 tonnes of waste plastic from other crops, eg brassicas. Disposal costs for carrots are more than £500,000 per year. Burning and burying of waste plastic has been outlawed since 2006 so, as recycling poses problems because of soil contamination and logistic difficulties, new solutions are urgently needed.
HDC project FV 280 tested some of the new breed of biodegradable crop covers and had encouraging results.
The biodegradable crop covers, derived from oil or corn starch and used over early crops of carrots and lettuce, produced crops equivalent in yield and earliness to those grown under standard commercial crop covers.
Trials with calabrese were not successful due to sheets not being wide enough for this crop, ie the narrow widths led to physical damage and restricted growth. One early crop cover, "Mater-bi", made from corn starch, when removed, left in the wheelings and covered in soil had degraded by October, but others tested would need to be removed and composted elsewhere.
Field-stored carrot crops, over-wintered under biodegradable covers and covered with straw, produced crops of broadly similar yield and marketability to those under the standard black plastic and straw, except for the latest removal dates where there was a slight reduction in marketability.