Effects of calcium carbonate and organic matter on soil aluminum, manganese, iron, zinc and copper and their concentration in corn plants in Greek acid soils
Tsakelidou, K; Karagiannidis, N; Bladenopoulou, S
A pot experiment using corn (Zea mays L.) as the test plant was conducted in a greenhouse to study the influence of soil pH on the release of aluminum (Al), manganese (Mn), iron (Fe), zinc (Zn), and copper (Cu) to plants in three acid soils from northern Greece. The soils used in this study belong to Inceptisols with sandy clay loam (soil I), loamy sand (soil II), and sandy loam (soil III) texture. Acid soil materials were treated with 6 CaCO3 and 4 manure levels to give a pH (H2O) range in average of the three soils from 4.14 to 6.83, after CaCO3 was added, and from 4.14 to 5.87, after the addition of animal manure. Increased soil pH due to calcium carbonate (CaCO3) or organic matter (OM) generally had suppression effects on the solubility of Al, Mn and Fe, approaching on the average minimal values at pH 6.83 (CaCO3) or 5.87 (OM). Both amendments declined sharply Zn activity in soil solution in soil II, but increased it, to some extend significantly, in soils I and III. Similar results were noticed for soil Cu. Plant analysis showed that elevated soil pH decreased shoot Al and Fe concentration and accumulation in plants grown on soil II, but increased them in the plants grown on the soils I and III, in spite of the corresponding decrease of soil Al solubility and availability. Shoot Mn concentration and accumulation of the plants grown on all three soils decreased sharply with increasing levels of CaCO3 or OM. Soil and plant analysis and toxicity symptoms in the untreated plants grown on the soils II and III suggested Mn and Al toxicity which may have been the major cause of yield depressions at low pH. Increases in CaCO3 or OM levels caused significant decreases in shoot Zn concentration and accumulation in soil II and to some extend in soil III, whereas the corresponded changes in soil I were insignificant and no consistent. Observed changes in tissue Cu concentrations as a function of soil pH were not significant. Regression analysis showed that soil pH was generally negatively correlated with soil Al, Mn or Fe. Soil Zn was significant correlated with pH, negative in soil II, but positive in the soils I and III. All the other correlations between pH and the above elements or among these elements were depending on the kind of treatment, element, and soil used.