In contrast to cropping patterns, cropping systems include not only the share of crops in time and space but also all related cultivation practices applied to the crops, e. g. soil cultivation, pesticide and fertiliser application. Arondel and Girardin (2000) proposed for a farm network with maize production in the Rhine plains a way of sorting cropping system (CS), in order to assess their impact on groundwater quality, by defining categories of impact and families of criteria. The categories (C1-C4) were as follows:
- C1: CS with a very high environmental risk level (risk caused by an error of practice)
- C2: CS resulting in environmental problems (common agricultural practice)
- C3: CS aimed at preserving environment (use of improved methods)
- C4: CS respecting the environment (important imvolvement of the farmer for protecting the environment)
Groundwater quality is highly influenced by three agricultural techniques: nitrogen management, pesticide management and irrigation management. In order to categorise cropping system, evaluation criteria were defined as follows:
|for nitrogen management||for pesticide management||for irrigation management|
The evaluation criteria thus can be interpreted as compound indicators to assess the risk of groundwater pollution due to defined cropping systems.
Arondel and Girardin (2000) did not refer to data of (ground- or surface) water quality for the calibration of the categories.
This study shows that the description of a cropping system may be quite complex, as a number of indicators are needed. However, the three categories of indicators are common: one is needed for the description of nitrogen fertilisation, the other for the description of pesticide applications. The last category describes indicators for the water balance which can influence both pesticides and nitrogen transfers. In this specific study, climatic data were not applied to assess the hydric balance.