Policies aimed at reducing plant protection products (PPPs) are part of the UN’s 2030 Agenda for Sustainable Development. Sustainable management of PPPs is crucial for soil health, biodiversity, and ecosystem services, including food provision. While PPPs can control pests and enhance agricultural yields, they also pose environmental and health risks by contaminating water, soil, and non-target organisms through airborne drift. Investigating innovative and more sustainable distribution methods can support sustainability goals. This study aimed to evaluate the potential impact of the pesticide Spintor® Fly on non-target soil organisms in olive orchards comparing two spraying methods: a traditional Casotti® pump mounted on a tractor and an innovative Unmanned Aerial Vehicle (UAV) developed for the project. The study was conducted in 2021 in an organic olive orchard, which was divided into two plots: a Casotti-treated plot (CAS) and a drone-treated plot (DRO). A strip of uncultivated land at the edge of the orchard was used as a (non-treated) control plot (CAP). The impact on native soil microarthropod communities was assessed using the arthropod-based Soil Biological Quality Index (QBS-ar) and Bait Lamina Test (BLT). Soil samples were collected for earthworm avoidance tests and soil chemical–physical analysis. The results obtained with QBS-ar and BLT indicated no significant differences between DRO and CAS, in both sampling periods (pre- and post-treatment). However, DRO generally exhibited slightly better performance than CAS. The avoidance behaviour was confirmed for both CAS and DRO, although it was lower for the latter. Overall, drone aerial spray performed slightly better, suggesting a potentially lower impact on soil communities. Our results provide initial clues for the sustainable use of drones in agriculture with no increased risks for soil health compared to traditional methods. Further long-term studies should be conducted to validate these findings and possibly confirm the long-term benefits of drone applications compared to traditional methods.
Plant Protection Products (PPPs) are widely used to maintain high productivity and protect crops, but can have unintended toxic effects on beneficial non‐target soil organisms. To avoid unacceptable adverse effects of PPPs on soil organisms, a prospective risk assessment is carried out, which focuses on individual substances and their effects on a few individual species or groups. However, the reality of agricultural soils consists of complex networks of organisms exposed to mixtures of several PPP active substances. It is therefore essential to monitor PPP residues in soils. This paper describes the ConSoil project and its proposed framework for monitoring PPP residues in Swiss Agricultural soils which includes and integrates (1) risk‐based reference values for PPP residues in soil and (2) indicators of their effects on long‐term soil fertility. For risk‐based reference values, a proposal has been developed to derive Soil Guideline Values (SGVs) for PPP residues and a mixture risk assessment concept is being developed. Regarding indicators, a toolbox of ecological and ecotoxicological indicators will be proposed to reflect the protection goal of long‐term soil fertility in agricultural soils. For this objective, standardised and/or well‐established bioindicator methods will be selected for the key soil organisms that support soil fertility. To integrate SGVs and the biomonitoring toolbox, an adapted TRIAD approach is proposed, where generic SGVs are used as a screening tool to identify monitoring sites potentially at risk and to trigger more detailed monitoring. Detailed monitoring will refine the SGVs based on site‐specific characteristics and implement the bioindicator toolbox to measure the effects of PPP residues and their risk to long‐term soil fertility. As a novel integrated framework, it is essential to use the data generated in detailed assessments to calibrate and refine the SGVs and bioindicator tools and improve the monitoring over time.
1 November 2024 in Integrated Environmental Assessment and Management
The bait-lamina test is an easy and efficient method to quantify the feeding activity of soil invertebrates. However, under natural conditions, feeding activity is influenced by environmental factors such as soil moisture content, whose effects on test outcomes remain insufficiently quantified, complicating interpretation. In this study, we optimized the bait-lamina test under laboratory conditions, to assess the influence of soil moisture content on feeding activity of the earthworm Eisenia andrei and the enchytraeid Enchytraeus albidus , using LUFA 2.2 standard soil (LUFA Speyer, Speyer, Germany) as a substrate. Feeding activity increased linearly with increasing soil moisture until an optimal moisture content, which was 52% of the maximum water holding capacity (WHC) for earthworms, and between 49 and 68% WHC for enchytraeids. Above these optima, feeding activity was reduced and was less dependent on soil moisture. The increase in feeding activity up to the peak was described by different slopes for the two species. Earthworms consumed the bait faster (on a per unit weight basis) than enchytraeids. Among the two species, the relationship established for E. albidus was the more similar to the response obtained in field conditions. Within the range of soil moistures considered by the model, our results demonstrate that feeding activity is positively correlated with soil moisture for two important soil invertebrates, although this increase, the optimal soil moisture content, and the speed of bait consumption are species-dependent. The model produced provides a first quantitative framework describing these relationships and can serve as a basis for future studies testing its applicability across different soil types. Such research would represent a first step for normalizing results from bait lamina tests under field conditions.
The bait-lamina test is an easy and efficient method to quantify the feeding activity of soil invertebrates, commonly performed under field conditions to measure the impact of chemicals on soils. However, under natural conditions, feeding activity is also influenced by environmental factors such as soil moisture content. The extent of this influence on the results of the bait-lamina test is still poorly described and this can complicate their interpretation. In this study, we optimized the bait-lamina test under laboratory conditions, to assess the influence of soil moisture content on feeding activity of the earthworm Eisenia andrei and the enchytraeid Enchytraeus albidus, using LUFA 2.2 soil as a substrate. Feeding activity increased linearly with increasing soil moisture until a peak was reached, at a moisture content of 52 % of the maximum water holding capacity (WHC) for earthworms, and 68 % WHC for enchytraeids. Above the optimal moisture content, feeding activity was reduced and was less dependent on soil moisture. The increase in feeding activity up to the optimal moisture content was described by different slopes for the two species. Earthworms consumed the bait faster (on a per unit weight basis) than enchytraeids. Among the two species, the relationship established for E. albidus was the more similar to the response obtained in field conditions. Within the range of soil moistures considered by the model, our results demonstrate that feeding activity is positively correlated with soil moisture for two important soil invertebrates, but this increase, as well as the optimal soil moisture content, and the speed of bait consumption are species dependent. The model produced represents a first step for normalizing results from bait lamina tests in the field laying the foundation for future studies to validate its applicability across different soil types and field conditions.