Effects of Phosphorus Supplies on the Nutritional Status of Maize (Zea mays L.)
2014
Izsáki, Zoltán
The effects of soil phosphorus (P) supplies on the yield and nutritional status of maize and on interactions between individual nutrients was studied in a long-term maize fertilization experiment set up in 1989 on a chernozem meadow soil calcareous in the deeper layers, with four levels each of nitrogen (N), P, and potassium (K) supplies. The present article discusses the P fertilization results obtained in years 12–19 of the experiment, between 2001 and 2008. Depending on the P fertilizer level, the ammonium (NH ₄)–lactate (AL)–phosphorus pentoxide (P ₂O ₅) content of the ploughed layer ranged from 120 to 360 mg kg ⁻¹. Maximum grain yields were recorded at AL–phosphorus pentoxide (P ₂O ₅) levels of 160–220 mg. Leaf analysis at the beginning of tasselling indicated that, on the basis of correlation analysis on the maize leaf P concentration and the yield, the limit values for satisfactory P supplies were 0.20–0.37 P% for a yield level of 10–14 t ha ⁻¹. In most years the P supply level had an influence on the zinc (Zn) and copper (Cu) nutritional status of maize. The P-Zn antagonism that accompanies increasing P supplies was increasingly experienced from a soil AL-P ₂O ₅ level of 160 mg kg ⁻¹, and P-Cu antagonism from a level of 190 mg kg ⁻¹. The leaf Zn concentration required for a yield of 10–14 t ha ⁻¹ was 10–32 mg kg ⁻¹, with a P/Zn ratio of 80–330, whereas the satisfactory Cu concentration in the present experiments was 2–11 mg kg ⁻¹. In most years the satisfactory P/Cu ratio was 250–550, but high yields can still be achieved at a P/Cu ratio of 900–1100. The N, K, calcium (Ca), magnesium (Mg), iron (Fe), and manganese (Mn) concentrations of the maize leaf at tasselling were not influenced by the P supplies in the majority of years.
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