A meszezés hatása a homoktalaj oldható szerves-szén- és szerves-nitrogén-tartalmára tenyészedény-kísérletben | Effect of liming on the dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) contents of sandy soil in a pot experiment

The effect of two different liming materials (calcite and dolomite) on the dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) contents of the soil was investigated in a pot experiment on an acidic sandy soil (Arenosol) using oats (Avena sativa L.) as indicator plant. The major physical and chemical properties of the soil were as follows: pH(H ₂O): 4.38; pH(KCl): 3.42; y ₁: 12.6; Upper limit of plasticity according to Arany (KA): 31; T (cmol+/kg): 2.7; Humusz (%): 0.66 (very poor N supply); AL-P ₂O ₅ (mg/kg): 179 (good P supply); AL-K ₂O (mg/kg): 87 (poor K supply). The experiment was set up in a complete factorial design with 7 treatments in 9 replications. The treatments are listed in Table 1. The same NPK doses were applied in all the treatments: 1 g N, 1 g P ₂O ₅, 1 g K ₂O/pot. Samples were taken three times during the growing season (in the 6 ᵗʰ, 10 ᵗʰ and 15 ᵗʰ weeks). The lime rates applied were 0, 11, 22 and 33 g/pot calcite and 10.1, 20.2 and 30.3 g/pot dolomite. The DOC concentration significantly increased with increasing lime doses at all three samplings owing to increased pH and microbial activity. An exponential relationship was found between soil pH and DOC concentration: y = 0.3733e ⁰.⁷⁸⁹³ˣ, r = 0.903***. There was only a significant lime effect on the DON concentration at the first sampling. During the rest of the growing period there was no significant increase in the DON concentration as the lime doses increased. This can be explained by the fact that the biodegradation of DOC and DON takes place at different rates under the given experimental conditions, resulting in a decrease in the N content of the dissolved organic matter, though this latter increased with increasing pH. There were no significant changes in the dissolved organic carbon content of the soil during the 15-week growing period, while the DON concentration significantly decreased. Higher DOC and DON concentrations were measured for calcite than for dolomite, but this was not confirmed statistically.