The effect of various nitrogen fertilization and foliar nutrition regimes on the concentrations of nitrates,ammonium ions,dry matter and N-total in carrot (Daucus carota L.) roots

Two field experiments (Experiment I in 2003–2005 and Experiment II in 2004–2005) with carrot c.v. ‘Kazan F₁’ were conducted at Trzciana village (50°06′N, 21°85′E). The experiments were arranged in a split-plot design with four replications. Two sub-blocks were identified in both experiments: I, without foliar nutrition; II, receiving plant foliar nutrition. The plants were sprayed three times alternately with: 2% urea solution, 1% solution of multi-component ‘Supervit R’ fertilizer (produced by Intermag, Poland) and again with 2% urea solution. Combinations with diversified nitrogen fertilization were distinguished within both sub-blocks. Experiment I comprised of: (1) Control, (2) Ca(NO₃)₂ 70, (3) Ca(NO₃)₂ 70 + 70, (4) (NH₄)₂SO₄ 70 and (5) (NH₄)₂SO₄ 70 + 70. Experiment II included: (1) Control, (2) ENTEC-26 35 + 35, (3) ENTEC-26 70 + 70, (4) ENTEC 26 105 + 105, (5) NH₄NO₃ 35 + 35, (6) NH₄NO₃ 70 + 70, (7) NH₄NO₃ 105 + 105. Where 70 kg N ha⁻¹ was used before sowing, whereas 35 + 35, 70 + 70 and 105 + 105 kg N ha⁻¹ were applied before sowing and as top dressing. Solid nitrogen fertilizer was added to the soil (produced by): Ca(NO₃)₂, Yara International ASA (Hydro); (NH₄)₂SO₄, Zak?ady Azotowe in Tarnów, Poland; NH₄NO₃, Zak?ady Azotowe in Pu?awy, Poland; and ENTEC-26, COMPO GmbH & Co. KG, Germany. The research aimed at determining the effect of diversified nitrogen fertilization and foliar nutrition on NO₃⁻, NH₄⁺, N-total and dry matter (d.m.) concentrations in carrot, and N uptake by storage roots. In Experiment I, nitrogen fertilization did not affect NO₃⁻ concentration, whereas in Experiment II, the applied N treatment increased NO₃⁻ concentration in carrot in relation to the control, except for the storage roots of plants fertilized with ENTEC-26 35 + 35. Nitrogen fertilization applied in both experiments caused a significant increase in N-total concentration in carrot and N uptake by storage roots in comparison with the control plants. In both experiments, nitrogen fertilization had a different effect on the concentrations of NH₄⁺ and d.m. in carrot. What is more, foliar nutrition treatments in both experiments had a different effect on the concentrations on NO₃⁻, N-total, d.m. in carrot and N uptake by carrot storage roots.