Antonis Mistriotis

Plastic Nets in Agriculture: A General Review of Types and Applications

At the moment, there are a large number of agricultural net types on the market characterized by different structural features such as type of material, type and dimensions of threads, texture, mesh size, porosity / solidity and weight; by radiometric properties like color, transmissivity/reflectivity/shading factor; by physical properties like air permeability and several mechanical characteristics such as tensile stress, strength, elongation at break, and durability. Protection from hail, wind, snow, or strong rainfall in fruit-farming and ornamentals, shading nets for greenhouses and nets moderately modifying the microenvironment for a crop are the most common applications. A systematic review of the current state-of-the-art of structural parameters, standard and regulations, most common agricultural net applications, and their supporting structures has been developed by means of a literature study, technical investigations, concerning characteristics and use of nets. As a result, the survey highlighted that in many cases different, not even similar, net types were adopted for the same application and the same cultivations by various growers. Results show that neither growers nor net producers have clear ideas about the relationship between the net typology optimization for a specific application and the construction parameters of the net. The choice often depends on empirical or economic criteria and not on scientific considerations. Moreover, it appears that scientifically justified technical requirements for nets used in specific agricultural applications have not been established yet.

Assessing Marine Biodegradability of Plastic—Towards an Environmentally Relevant International Standard Test Scheme

In the process of becoming independent from fossil hydrocarbon resources bio-based plastic is one option, being also favoured by programmes of the European Commission. To achieve maximum sustainability bio-based polymers that are also biodegradable are entering the market, with nationally differing regulation. It is wise to assess the risk of these new materials especially in fields where their use is intrinsically linked to a loss to the environment (e.g. by conversion to micro-plastics through wear), or where unintentional littering is probable. Thus, standard tests (e.g. ISO) are needed to validate the claim of a material being “biodegradable” for consumer safety and environmental impact. Here we give an overview of current marine standard tests and present results from the EU-funded project Open-Bio on the development of tests of biodegradability under marine conditions. We present feasible field test systems for three coastal scenarios: plastic being buried in intertidal beach sand (eulittoral test), plastic floating in the shallow water column (pelagic test) and plastic sunken to the sandy sublittoral (benthic test). The field tests were optimized to a state that the test material could be observed in situ over a time of up to 2 years without loss of larger fragments, and marine disintegration could be followed for common biodegradable polymers. Degradation rates for the tested polymers are given. A set of mesocosm experiments simulating the same three habitats supported the field research in a semi-controlled setting of environmental conditions, and allowed to critically evaluate field and lab test results, leading to an environmentally relevant test scheme. Our outlook shows the next steps of test development needed to provide a comprehensive toolset to cover the majority of conditions in which plastic is found in the marine realm.