Nitrate immissions into groundwater is an actual environmental problem. Agriculture is the main polluter causing nitrate leaching with a set of farming practices that affect the nitrogen turnover in the soil crop system (see image). The main factors within agricultural landuse that influence nitrate leaching are:

• Amount of nitrogen fertiliser applied
• Type of fertiliser
• Time and frequency of fertilisation

To assess different production practices regarding their potential to contribute to nitrate leaching four parameters were introduced:

1. Total N-fertilisation
2. Frequency of fertilisation
3. Amount of nitrogen applied in autumn
4. N-balance after harvest

All alternative production practices of all crops defined for the model were rated by their goal achievement levels using the fuzzy tool with the optimum goal being a minimum of nitrate leaching.
Consequently the set aside option is best rated because no nitrogen is applied to the plots. In average with a wide range of variation cereals are rated good (> 0,7).
Moderate to poor ratings were given for sugar beets, maize for silage, potatoes and winter oilseed rape.