Abstract:The objective of this study was to determine the degrability/biodegradability of disposable plastic bags available on the market that are labeled as degradable/biodegradable and those certified as compost. The investigated materials were obtained from chain stores in the Czech Republic and Poland. Seven kinds of bags (commercially available) were used in this study. One of them was a disposable bag made of HDPE and mixed with totally degradable plastic additive (TDPA additive). Another was a disposable made of polyethylene with the addition of pro-oxidant additive (d2w additive). One was labeled as 100% degradable within various periods of time, from three months up to three years, and four were certified as compostable. The test was carried out in a controlled composting environment. The biodisintegration degree of the obtained pieces was evaluated following a modified version of ČSN EN 14806 Norm ''Packaging -Preliminary evaluation of the disintegration of the packaging materials under simulated composting conditions in a laboratory scale test" and a modified version of ČSN EN ISO 20200 "Plastics -Determination of the degree of disintegration of plastic materials under simulated composting conditions in laboratory-scale test" (ISO 20200:2004). The emphasis was put on determination whether the bags are degradable/biodegradable or not.

Biodegradation of plastics bags advertised as 100%-degradable or certified as compostable was tested in composting conditions. Samples were placed into frames and inserted into one clamp within the compost pile to investigate the biodegradation. The plastics bags were obtained from chain stores in the Czech Republic and Poland. The shopping bags were made of HDPE with the TDPA additive (sample 2), PP with an addition of pro-oxidants (d2w) (samples 1, 3) and materials certified as compostable (starch, polycaprolactone) (samples 4, 5, 6, 7). Control sample (cellulose filtering paper, sample 8) was to check the potential of biological decomposition in the tested environment. At the end of the 12-week experimental period it was found that the polyethylene samples with the additive (samples 1, 2, 3) had not been decomposed, their colour had not changed and that no degradation neither physical changes had occurred (did not biodegrade). Samples certified as compostable (samples 4, 5, 6, 7) were decomposed. The results at the municipal compost facility demonstrate that the compostable plastics biodegrade and polyethylene samples with the additive did not biodegrade in compost.

The paper is focused on the current status of land consolidation in Czechia. The survey is based on a questionnaire distributed electronically to municipalities and related subjects (agricultural organizations, farmers) in areas where the land consolidation has been completed, is in progress, or is under preparation. Small farmers and municipality representatives perceive the land consolidation as a measure facilitating permeability of the landscape and protection from erosion and/or from flooding. Land consolidation is important for companies in clarification of the land ownerships and as a remedy for the landscape needs. About half of the respondents believe that the measures have rather brought benefits, whereas 41% of respondents mainly highlight problems. The negative side of the land consolidation is mostly seen in the time delays and demanding administration; agribusinesses also point out complications with land management. Nevertheless, 75% of small farmers and municipalities and 62% of agribusinesses are interested in land consolidation. The main differences between small farmers and large companies consist in their attitude to reduction of the acreage of large plots and their division by common facilities.

ADAMCOVÁ DANA, VAVERKOVÁ MAGDALENA, TOMAN FRANTIŠEK: Repeated research of biodegradability of plastics materials in real composting conditions. Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis, 2013, LXI, No. 6, pp. 1557-1564

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