Effect of long-term cattle slurry and mineral N, P and K application on concentrations of N, P, K, Ca, Mg, As, Cd, Cr, Cu, Mn, Ni, Pb and Zn in peeled potato tubers and peels

Little information is available on how fertilizer application affects concentration of many elements in peeled potato (Solanum tuberosum) tubers and peels. We analyzed how long-term application of cattle slurry and mineral N, P and K fertilizers affects the yield of tubers, their dry matter content and concentrations of elements. In 2009, potatoes tubers were collected in control, cattle slurry (CS), mineral N4P2K2 and combined CSN4P2K2 treatment of the Ruzyně Fertilizer and Crop Rotation Experiment established on Illimerized Luvisol in Prague (Czech Republic) in 1955. Amount of N, P and K supplied by CS was 138, 30 and 172 kg/ha and the amount supplied by N4P2K2 was 110, 31 and 186 kg/ha. Yield of fresh potatoes ranged from 20.6 in the control up to 31.2 t/ha in CSN4P2K2 treatment. Dry matter content of unpeeled tubers, peeled tubers and potato peels was not significantly affected by fertilizer treatments probably because of not excessive N application. Normal cropping practices with application of CS and mineral N, P and K fertilizers did not significantly increase concentrations of trace elements in peeled tubers or potato peels on neutral soil with low trace elements availability. Concentrations of many elements (N, P, K, Ca, Mg, Cd, Cr, Cu, Mn, Ni, and Zn) were higher in potato peels than in peeled tubers, but the differences in the case of trace elements were relatively small.