| Summary: | The use of activated humic acids (HAs) in agricultural applications is a relatively recent development. Corn (Zea
mays L.) is a major food and silage crop in Turkey and yields are reduced in calcareous soils by sodium (Na) toxicity
and carbonate (CO3
) induced deficiencies of some micronutrients. In this study, the effects of two HAs extracted using
the wet-alkali technique and activated with nitrogen (N2
) and oxygen (O2
) gases, on the Na and micronutrient (iron
(Fe), manganese (Mn), zinc (Zn), copper (Cu) and boron (B)) concentrations in the homogenised stems and leaves
of corn plants were investigated. The experiment was conducted with a completely randomized design with factorial
arrangement (2 HA types × 2 fertilisation regimes × 5 HA concentrations), with three repetitions, in a calcareous soil
in pots in a greenhouse. The humic acid was applied at 100, 200, 400, and 800 mg/kg of soil before sowing the corn
seed. The variance analysis showed that increasing HA levels decreased the Na concentration in the corn plants. The
lowest plant Na concentrations were obtained with the addition of HA activated with N2
and O2
to both the fertilised
and unfertilised treatments. The highest Zn and Cu uptakes, and Fe, Mn, and B uptakes, were associated with wet alkali
extraction and gas activation, respectively. Overall, HA extracted with N2
/O2 was more effective under unfertilised
conditions and wet extracted HA was more effective under fertilised conditions.
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