Field crops are grown outdoors, so application of pesticides to field crops by definition implies emission to the environmental compartments air and soil. However, there are immense differences in the degree to which pesticides are mobile and biologically active in the environment. Consequently, pesticide use options available to farmers which may be of similar cost and effectiveness may differ strongly with respect to environmental impact (Van der Werf, 1996). How can a farmer take into account the risk for the environment when he can choose between several pesticides?
A research team at the French National Institute for Agronomic Research (INRA) at Colmar in north eastern France has set up a system to assess the impact of cultivation practices - such as fertiliser and pesticide use, crop rotation - on the agrosystem and its environment. The team has proposed a set of agro-ecological indicators (AEI) that are calculated from data available on the farm without requiring specific field measurements (Bockstaller et al., 1997). AEI are expressed on a scale between 0 and 10 to make them easy to use. The value 7 represents the achievement of a minimum level of sustainability of the farming system. A value below 7 indicates that the minimum requirement for sustainability is not met, a value above 7 indicates that the farmer does better than the minimum requirement. The reference level of 7 is based on scientific knowledge or expert judgement. AEI are primarily tools to aid the decision-making process and help farmers adapt their cultivation practices and farming system towards increased sustainability. However, AEI may also be used by decision makers to monitor or evaluate agro-environmental policies. Within this framework the INRA team has built an expert system, known as "Ipest" that ranks the environmental impact of pesticide applications in field crops (Van der Werf & Zimmer, 1998). This work was funded by a Research Training Fellowship of the European Union.
For a pesticide application an environmental impact score is calculated from three types of input variables: a) pesticide characteristics (e.g. toxicity to water organisms), b) environmental characteristics (e.g. the runoff risk of the field), c) application characteristics (e.g. the site of application: on the crop, on the soil, in the soil). The effect of these input variables on the risk of environmental impact can be expressed in every-day language, e.g.: If the runoff risk of the field is large and the pesticide is applied on the soil and the pesticide is toxic to aquatic organisms then the risk of surface water contamination is large. For a pesticide application the expert system consisting of a collection of rules of this type allows the calculation of the value of four modules: P (presence, reflecting amount of pesticide applied), Rgro (risk of groundwater contamination), Rsur (risk of surface water contamination) and Rair (risk of air contamination). This calculation which involves functions describing membership to fuzzy subsets will not be detailed here. The values of these modules are aggregated according to another set of decision rules to yield a value for total risk (Rtot) between 0 (no risk of environmental impact) and 1 (maximum risk of environmental impact).
Results are presented in the table. This type of results can be used to compare or rank different pesticide applications with respect to the value of one or several of the modules or of the Rtot value. The system contains data for about 135 pesticide active ingredients, data on other active ingredients can be simply added. The European Union currently funds a concerted action to compare and evaluate this method and seven other pesticide risk assessment tools developed at a number of research institutes across Europe.
Our expert system reflects an expert perception of potential pesticide environmental impact. It can be used as a decision support to rank or choose between alternative pesticide application options. The system has a modular structure and thus provides both a synthetic indicator reflecting overall impact as well as more detailed information through its four modules. New modules can be added if necessary. The system is flexible and can be tuned to expert perception.
The values of the modules Presence (Pres.), Risk of surface water contamination (Rsur), Risk of groundwater contamination (Rgro) and Risk of air contamination (Rair), and of the overall risk Rtot for a number of pesticides applied at their recommended rate in a field with major runoff risk and moderate leaching risk. Rate of application and position of application are given.
Pesticide
nameRate
(kg ha-1)Position1
Pres.
Rsur
Rgro
Rair
Rtot
2,4-D
0.300
on c/s, 50%
0.49
0.31
0.24
0.00
0.31
alachlore
2.400
on c/s, 0%
0.90
0.74
0.21
0.00
0.68
atrazine
1.000
on c/s, 0%
0.75
0.70
0.75
0.00
0.62
carbofuran
0.600
in soil
0.64
0.10
0.60
0.00
0.42
cyfluthrin
0.040
on c/s,100%
0.10
0.10
0.00
0.61
0.24
EPTC
3.600
in soil
0.95
0.10
0.00
0.10
0.15
glyphosate
4.300
on c/s, 100%
0.96
0.10
0.00
0.00
0.12
isoproturon
1.800
on c/s , 10%
0.86
0.80
0.26
0.00
0.68
lindane
1.200
on c/s, 0%
0.79
0.98
0.42
0.56
0.80
parathion
0.300
on c/s, 100%
0.49
0.10
0.00
0.40
0.27
pendimethalin
2.000
on c/s, 0%
0.87
0.93
0.00
0.70
0.81
rimsulfuron
0.015
on c/s, 5%
0.01
0.37
0.00
0.00
0.09
1
on c/s : applied on the crop and/or on the soil, the percentage indicates the fraction of soil covered by the crop at the time of application; in soil: applied in the soil.
References
Bockstaller Ch, Ph Girardin & H M G van der Werf, 1997. Use of agro-ecological indicators for the evaluation of farming systems. European Journal of Agronomy 7: 261-270.
Van der Werf H M G, 1996. Assessing the impact of pesticides on the environment. Agriculture, Ecosystems and Environment: 60: 81-96.
Van der Werf H M G & Ch Zimmer, 1998. An indicator of pesticide environmental impact based on a fuzzy expert system. Chemosphere 36 (10): 2225-2249.
Dr. Hayo van der WerfAddress:
INRA,
Unité d'Agronomie de Rennes-Quimper,
ENSAR - 65, rue de Saint Brieuc
35042 Rennes,
FrancePhone: +33 (2) 9928 2709
E-mail: Hayo.vanderWerf@roazhon.inra.frDr. Hayo van der Werf studied at Deventer Agricultural College and the University of Wageningen (both in the Netherlands) and at the University of Guelph (Canada). He works at the Rennes-Quimper Soil and Agronomy Research Unit, which is located in Brittany, a beautiful maritime region, heavily affected by pollution caused by agriculture. The research unit is part of the department of Environment and Agronomy of the French National Institute for Agronomic Research (INRA). Dr. van der Werf's current subject of research is: the assessment of the sustainability of farming systems, with a particular focus on the evaluation of pesticide environmental impact. Previously he conducted research into the crop physiology and agronomy of hemp and maize.