Effect of fertilizing systems on the content of nitrogenous substances and heavy metals in potato tubers | Влияние удобрений на содержание азотистых веществ и тяжелых металлов в клубнях картофеля

Field experiments were hold at Novozybkov Experimental Station (Bryansk Region) on sandy podzol soil (humus content was 2.4-2.5%) in 2001-2004. Different fertilizer compositions (FC) and chemicals for plant protection were tested and their influence on content of nitrogen compounds and heavy metals (HM) in potato tubers was under study. The field rotation included potato, oat, lupine, winter rye. Organic, organomineral and mineral fertilizers were applied in spring before tillage. Mineral fertilizers NPK were used at rates of 75:30:90 kg/ha, 2(NPK) and 3 (NPK). The highest content of crude protein (2.62%) in tubers was determined after using 3 (NPK) – N 225P90K270 kg/ha. The highest protein yield (456 kg/ha) was done after using organomineral FC together with pesticides (manure at a dose of 40 000 kg/ha +NPK+pesticides). Nitrate N and HM content in potato tubers depended on weather conditions and FC. The most accumulation of the N (242 and 278 mg/kg) was fixed for application 2(NPK) and 3(NPK) respectively together with pesticides. At this nitrate N content increased if water deficiency was in the 2 half of vegetation period. Application of organomineral and mineral 2 (NPK) FC improved amino acid composition of tuber proteins. Chemicals for plant protection did not have a high effect on amino acid content in tubers. The highest content of Zn, Cu and Pb in potato tubers was fixed in 2002 under drought conditions. The minimum content of Cu and Pb was caused by application of 2(NPK). HM content was less than maximum concentration limit (for Zn and Pb in 1.5-2 times, for Cu in 7-10 times) applying the all types of FC. The conclusion was done that the applied FC supply products safe by HM content.