Assessing the effects of plant protection products on organic matter breakdown in arable fields—litter decomposition test systems

There is a need for plant protection products (PPPs) to be assessed for their effects on the breakdown of organic matter (OM), which is an important functional process in terrestrial ecosystems. Little information is available on to how to assess effects of PPPs on this complex system and formal guidelines for a standardised test method are lacking. We critically reviewed the literature to determine appropriate methods to investigate OM breakdown for the risk assessment of PPPs. Five methods appeared to be potentially suitable: namely the use of mini-containers or litter-bags to enclose OM, cotton-strip and bait-lamina assays which provide an artificial OM substrate, and stable isotopes to track the chemical decomposition of OM. These methods were compared on the basis of 10 suitability criteria, which included ecological relevance, ease of use and relevance to risk assessors. Each test method has limitations but the use of litter-bags, which is the most frequently used method, has distinct advantages over the other approaches. Accordingly, literature describing OM breakdown in litter-bags when applying PPPs are reviewed, gaps in the methodology are highlighted and recommendations for the development of a standardised and validated test method are proposed.     

A laboratory test protocol to evaluate effects of plant protection products on mortality and reproduction of the predatory mite<Emphasis Type="Italic">hypoaspis aculeifer</Emphasis> canestrini (acari: laelapidae) in standard soil

We provide a test protocol to evaluate the effects of plant protection products on mortality and reproductive performance ofHypoaspis aculeifer (Acari: Laelapidae). The test design is in compliance with standard characteristics of extended laboratory studies as formulated by international expert panels dealing with non-target arthropod testing schemes. Potential effects on survival rates are evaluated by assessing mortality after an exposure period of 14 days that starts with protonymphs. The reproductive performance of surviving mites is studied by following the egg production of individually isolated females over a 7-day period. The hatching success of these eggs is assessed subsequently. Using several years’ data obtained from water control treatments, we propose criteria to evaluate the validity of individual experiments.     

Mineralisation and humification of plant matter in soil samples as a tool in the testing of soil quality

Since life is inevitably dependent on the assimilation and dissimilation of carbon, and since most of the organic carbon is bound in soil humic matter, the mineralisation and humification of plant carbon in soil should be monitored, so as to evaluate soil quality and avoid ecological risks. For this reason we suggested an incubation test of thirty days in duration with soil samples amended or not with lucerne meal as a source of plant carbon. During the incubation period, CO₂ release is to be measured repeatedly, and thereafter contents of humic acids (HA) and fulvic acids (FA) should be estimated and compared with those determined in the original soil samples. Our results obtained with samples from non-fertilized or long-term (?>?40 years) fertilized plots of two field trials indicate that fertilization by NPK?+ farm yard manure resulted in (i) a slight enhancement of C mineralisation, i.e., CO₂ release from soil, and (ii) a significant increases of HA and FA contents. Soil samples from a reclaimed mine spoil, and either fertilised or not with sewage sludge did not show distinct differences in the same parameters. The practicability of the incubation test as a tool in the monitoring of soil quality should be further proved using samples from differently affected soils.