Nav: Home

The effects of pesticides on soil organisms are complex

October 04, 2016

Research shows that the interactions between pesticides, tillage and fertilisation are complex with respect to effects on the myriad of life forms in the soil. Such interactions should be considered in risk assessment of pesticides.

Humans and earthworms have a common interest: the soil. To earthworms and multiple other organisms the soil is home and a food source. For humans, too, the soil is a source of food, through production of edible crops or crops for livestock feeding.

Soil cultivation includes tillage, addition of nutrients via mineral fertilisers or manure, and (on conventionally managed farms) pesticide use. How are earthworms and other organisms in the soil affected by pesticides? Are these effects simple, or are they modified by other management factors?

With support from the pesticide research program of the Danish Environmental Protection Agency (EPA), researchers from Aarhus University have studied this in the setting of a long-term tillage experiment. Micro-arthropods and microbial indicators were monitored during two cropping seasons of winter wheat populations of earthworms. Other aspects, including leaching potential, soil structure and decomposition of crop residues, were examined under laboratory conditions.

The results have been published in a report from the Danish EPA and confirm that the effects of pesticides are significantly affected by management practices.

Complex interactions

Efficient processing of crop residues and fertiliser input are important for the crop production in agriculture. Soil-dwelling organisms play a key role for these processes which maintain soil fertility, as well as physical and chemical properties of soils.

Pesticide use may influence the soil negatively if key functions are disturbed. Risk assessment of pesticides is therefore necessary, but should take into account the specific application.

Management practices other than pesticide application also influence soil organisms and their activity. Interactions between management practices should be taken into account when evaluating pesticide effects, the report concludes. The authors recommend evaluation of pesticides in test systems that also consider factors other than the direct exposure to a pesticide in connection with risk assessment.

Fertilisation and tillage modify pesticide effects

In the study, the choice of tillage method and nitrogen source exhibited many significant interactions with pesticide effects on the number and activity of soil organisms. A considerable seasonal and annual variation was also observed.

- The study shows that simple test systems with exposure of single organisms convey an incomplete picture of pesticide effects. Knowledge about interactions between pesticide application and other management practices may help improve our understanding of the fate and effects of pesticides in natural environment, according to the report.

The researchers used a long-term tillage experiment at AU Foulum, the research centre of Aarhus University in Tjele, for the study. The researchers studied pesticide effects in both moldboard ploughed soil and directly seeded (no-till) soil. Either mineral fertiliser or cattle slurry was applied to the soil and either a fungicide or an insecticide, or both. All combinations of these treatments were included in the study which had in total 20 different treatments, all in four replicates.

Following the spring application of pesticides, and again after the winter wheat harvest in September, the researchers quantified populations of earthworms, springtails, mites, and microbial populations in the soil. They also examined nitrification potential, leaching risk, and several other aspects.

- The study confirmed that that there are significant interactions between management factors, including pesticide application, with respect to effects on soil organisms. There are many sources of variation, and the disturbance of tillage alone may be greater than the effects of pesticides, says senior researcher Søren O. Petersen from the Department of Agroecology. He states that the results have no direct implications for the current use of pesticides, but show that the authorities should be critical about the documentation offered on pesticide effects.
-end-


Aarhus University

Related Pesticides Articles:

SDHI pesticides are toxic for human cells
French scientists led by a CNRS researcher have just revealed that eight succinate dehydrogenase inhibitor pesticide molecules do not just inhibit the SDH activity of fungi, but can also block that of earthworms, bees, and human cells in varying proportions.
Pesticides deliver a one-two punch to honey bees
A new paper in Environmental Toxicology and Chemistry reveals that adjuvants, chemicals commonly added to pesticides, amplify toxicity affecting mortality rates, flight intensity, colony intensity, and pupae development in honey bees.
Hypertension found in children exposed to flower pesticides
Researchers at University of California San Diego School of Medicine found higher blood pressure and pesticide exposures in children associated with a heightened pesticide spraying period around the Mother's Day flower harvest.
Banned pesticides in Europe's rivers
Tests of Europe's rivers and canals have revealed more than 100 pesticides -- including 24 that are not licensed for use in the EU.
The persistence of pesticides threatens European soils
A study developed by researchers from the Diverfarming project finds pesticide residues in the soils of eleven European countries in six different cropping systems
Honeybees at risk from Zika pesticides
Up to 13 percent of US beekeepers are in danger of losing their colonies due to pesticides sprayed to contain the Zika virus, new research suggests.
Alternatives to pesticides -- Researchers suggest popular weeds
Research proves that extracts from S. nigrum and D. stramonium, globally existing weed species, may help to protect crop systems against agricultural pests.
Seeing pesticides spread through insect bodies
Osaka University-led team provides insights into the distribution of pesticides within insects using a newly developed method of insect sample preparation.
The more pesticides bees eat, the more they like them
Bumblebees acquire a taste for pesticide-laced food as they become more exposed to it, a behavior showing possible symptoms of addiction.
Research shows pesticides influence bee learning and memory
A large-scale study published by researchers from Royal Holloway University of London has drawn together the findings of a decade of agrochemical research to confirm that pesticides used in crop protection have a significant negative impact on the learning and memory abilities of bees.
More Pesticides News and Pesticides Current Events

Top Science Podcasts

We have hand picked the top science podcasts of 2019.
Now Playing: TED Radio Hour

Risk
Why do we revere risk-takers, even when their actions terrify us? Why are some better at taking risks than others? This hour, TED speakers explore the alluring, dangerous, and calculated sides of risk. Guests include professional rock climber Alex Honnold, economist Mariana Mazzucato, psychology researcher Kashfia Rahman, structural engineer and bridge designer Ian Firth, and risk intelligence expert Dylan Evans.
Now Playing: Science for the People

#541 Wayfinding
These days when we want to know where we are or how to get where we want to go, most of us will pull out a smart phone with a built-in GPS and map app. Some of us old timers might still use an old school paper map from time to time. But we didn't always used to lean so heavily on maps and technology, and in some remote places of the world some people still navigate and wayfind their way without the aid of these tools... and in some cases do better without them. This week, host Rachelle Saunders...
Now Playing: Radiolab

Dolly Parton's America: Neon Moss
Today on Radiolab, we're bringing you the fourth episode of Jad's special series, Dolly Parton's America. In this episode, Jad goes back up the mountain to visit Dolly's actual Tennessee mountain home, where she tells stories about her first trips out of the holler. Back on the mountaintop, standing under the rain by the Little Pigeon River, the trip triggers memories of Jad's first visit to his father's childhood home, and opens the gateway to dizzying stories of music and migration. Support Radiolab today at Radiolab.org/donate.