Pesticide Residues in Estonian Arable Soils Kadri Allik Priit Penu Estonian Agricultural Research Centre Soil Monitoring Bureau 11th Nordic Pesticide Residue Workshop June, 2015

Pesticide influence on soil Pesticide influences on soil depend on its composition and appearing time varieties. Significant negative impact of pesticides on soil biota has not been proved. Herbicides inhibit nitrogen producing bacteria. Fungicides and insecticides have influence on soil fauna. Insecticides affect N-cycle. Pesticides imapct on bacterial communites by reducing or changing their activity and composition. Pesticides cause decline in soil biodiversity. Source: European Soils

Guadeloupe and Martinique islands High quantity of chlordecone was used in banana cultivation. Soil contamination occured. Pesticides were carried to sea. Fishing was banned in costal ares. Social disaster emerged.

Limits for hazardous agents in soil Target, mg/kg Limit in residential areas, mg/kg Limit in industrial areas, mg/kg 2,4-D 0,05 0,5 2 DDT 0,1 5 Synthetic pesticides (total of active ingredient) 20 Data source: Regulation No 38 of the Minister of Environment, 11.08.2010. https://www.riigiteataja.ee/akt/13348997

Stockholm Convention on Persistent Organic Pollutants The convention covers following pesticides used in Estonia: toxaphene, hexachlorobenzene, polychlorinated biphenyls (PCB-s), hexachlorocyclohexanes, lindane, hexabromodiphenylether, pentabromodiphenylether, DDT. Hexachlorocyclohexanes banned in 1967 and chloro-organic pesticides import was banned in 1968. Estonian action plan of the Stockholm convention do not consider pesticide residues in soils as priority. Agent Duration of usage Total amount used, tonnes Reserves of agent Toxaphene 1967-1984 10,65 Unknown Hexachlorobenzene (HCB) 1970-1982 3,99 DDT 1957-1977 191,3

Determination of pesticide residues at present Agricultural Research Centre (ARC) laboratory is able to determine 300 active ingredients from soil using different chromatographic methods. In Soil Monitoring Bureau there are pesticides residues analysed in case of three studies or monitoring. The aim of collaboration between Ministry of the Environment, Agricultural Board and Agricultural Research Centre is to find additional ways to examine actually used active ingredients.

Studies in ARC including pesticide analysis Study about Minimum Soil Tillage (Soil Tillage Study) Study about Dynamics of Soil Nutrients in Nitrate Vulnerable Zone (NTA Study) Soil Monitoring Study as Part of National Environmental Monitoring Programme (Soil Monitoring Study) Gross Nutrient Balances and Pesticide Use Study Figure 1. Nitrate Vulnerable Zone in Estonia.

Results of different studies 2005-2014

Clean samples vs samples consist pesticides residues 2005-2014

The distribution of most common active ingredients

The comparison of pesticides in mulch and in soil (Soil Tillage Study)

Share of different pesticide residues in 2007-2014 (NTA Study)

Results of NTA Study 2007-2014

Active ingredients compared in NTA areas and other areas in 2014

Organic farming and pesticide residues In 2014 pesticide residues were found from a organic farming field. Buffer zones around the conventional tillage fields and organic farming fields are needed. Monitoring of arable lands under organic farming fields. Agricultural Board found pesticides (2,4-D, glyphosate) from products of organic farming in 2013. Control of pesticide residues needed in organic fields?

Organic farming and conventional tillage 331 land parcels found where arable lands under conventional tillage and under organic farming are next to each other. Figure 2. Organic farming field (green) between fields under conventional tillage.

Some observations Trifluralin (herbicide) remains in soil at least 4-5 years. MCPA (herbicide) remains in mulch longer than in soil. Fungicides remain in soil at least 6-7 months. Generally the content of pesticide residues is much lower than their target number. Some residues containing in soil are below its measurement error. In 2014 the first time was found total amount of pesticide residues (1,21 mg/kg) that overcome the target number (0,5 mg/kg).

Monitoring issues Method of sample collection time, depth of taking samples. Content of pesticides in the lower layers leaching. Applicable active ingredients vs capability of laboratory. Samples are collected after crop harvest in September and sometimes winter crop have already sowed. Even glyphosate residues were found, the concentration of AMPA was not detected. Determination problem? Decomposition product (DDE) of the DDT was found even at present, but it is below the determination limit (<0,01 mg/kg).

Thank you for the listening! © Arne Ader