No abstract

For a number of years Dravsko polje plain has been subject to intensive farming. Consequently, groundwater in this area is heavily contaminated with nitrates and pesticides. The goal of the study was to determine the quality of potatoes, based on nitrate levels cultivated in an area of contaminated groundwater. We also examined the influence of sustainable agriculture on the quality of crops. Nitrate content was determined using RP/HPLC/UV chromatography. Average nitrate content in potatoes cultivated on Dravsko polje plain was 157 mg/kg (range 18-429 mg/kg), which was not significantly different from the nitrate content in potatoes cultivated outside the contaminated area (mean value 145 mg/kg; range 28-448 mg/kg). In 18% of all samples, nitrate content exceeded maximum recommended levels. In potatoes cultivated via integrated production nitrate content did not significantly differ from the one in conventionally cultivated potatoes. In contrast, organic potatoes contained lower levels of nitrates (range 14-156 mg/kg). Our results also show that individual potato varieties are characterized by different trends of nitrate accumulation. Strict adherence to sustainable agriculture is reflected in lower levels of nitrate in potatoes.

To estimate the actual intake of nitrate by consumption of different lettuce varieties, 52 samples of lettuce of different origins and dandelion from 15 different areas of northeast Slovenia were analysed. For determination of actual nitrate content, a continuous flow method was used. The lowest nitrate content was detected in dandelion, with a mean value of 195 mg kg(-1) (ranging 47-487 mg kg(-1)). Nitrate content in lettuce of different origins ranged 85-3237 mg kg(-1), with a mean value of 1196 mg kg(-1). The mean nitrate content in organically cultivated lettuce was 890 mg kg(-1), which was considerably lower than the nitrate level in conventionally cultivated lettuce (1298 mg kg(-1)). Consumption of 100 g of dandelion would result in a maximal nitrate intake corresponding to 22% of the acceptable daily intake (ADI), with values up to seven times higher for lettuce.