Assessment of Environmentally Harmful Nitrogen Surplus by 0.01 M Calcium Chloride Soil Extractant in Long-Term Experiments

Abstract

Calcium chloride–extractable (1:10 soil/solution ratio, w/v) nitrate nitrogen (NO₃-N), ammonium nitrogen (NH₄-N), organic nitrogen (EON), and N_total fractions were measured in two long-term experiments. Both experiments are located in the Great Hungarian Plain. The first experiment was established on a Luvic Phaeozem soil and the second experiment was on a Calcic Chernozem soil. Researchers investigated the effects of long-term fertilization and irrigation on the amounts of nitrogen (N) fractions. Nitrogen rates caused significant increase in NO₃-N and N_total fractions. These fractions were in close correlation (r = 0.87; r = 0.88) with nitrogen balance. The nitrate content of the 200-cm-deep soil layer of soils under different nitrogen- and water-supply conditions were also studied. As an effect of N overfertilization, the maximum nitrate accumulation on nonirrigated plots occurred in the 200-cm depth, whereas on irrigated plots a nitrate accumulation layer could not be observed in the 200-cm-deep soil layer.

Keywords:

• Long-term experiments
• 0.01 M CaCl₂ extractable N forms
• nitrate leaching