Abstract

Nitrogen (N) is the most widely used fertilizer in agriculture for that reason the efficiency and type of fertilizers are constantly generated and evaluated. The objective was to evaluate N in potato development by ¹⁵N by three slow-release fertilizers (FLL). Clay-urea and potassium (AUK), three FLLs manufactured and was evaluated with traditional fertilization (Trad); with two doses of 70 kg N ha^-1 (N1) and 140 kg N ha^-1 (N2) and a control (0 kg N ha^-1) with ¹⁵N by the isotopic dilution technique. Accumulation in (1) vegetative growth (VG), (2) initiation of tuberization (IT), (3) tuber growth (TG), and physiological maturity (FM) was made. The Fertilizer N yield (RenNtot), the fertilizer N per difference (RenNfdif) and the isotopic method (RenNfiso), the recovery efficiency of N per difference (ERNdif) and isotopic (ERNiso) were determined. In RenNfdif and ERNdif, the higher dose was better and Trad outperformed FLL, in RenNfiso and ERNiso it was similar. Staged in RenNfdif, Trad outperformed the FLLs in all four stages and in RenNfiso, Trad and AUK1 showed better effect in all four stages. In FLL the source of N is Urea and in soils with alkaline pH the enzyme urease is not found and its effect was less than Trad, for that reason is not appropriate to use urea in these soils.

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