Transformations of inorganic-N in soil leachate under differing storage conditions

• Published in: Soil biology & biochemistry 2001-09, Vol.33 (11), p.1473-1480
• Main Authors: Clough, T.J., Stevens, R.J., Laughlin, R.J., Sherlock, R.R., Cameron, K.C.
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Ammonium; Biological and medical sciences; Chemodenitrification; Dinitrogen; Freezing; Fundamental and applied biological sciences. Psychology; Nitrate; Nitrite; Nitrous oxide; Physical properties; Physics, chemistry, biochemistry and biology of agricultural and forest soils; Soil science; Storage; Water and solute dynamics
• ISSN: 0038-0717; 1879-3428
• DOI: 10.1016/S0038-0717(01)00056-6

Incomplete recovery of 15N often occurs in 15N mass balance experiments, the unrecovered portion being assumed to be lost due to denitrification. Denitrification losses estimated in this way will be too high if any gaseous loss(es) of N occur during the sample collection, extraction or storage procedures. Leachate or KCl extracts of soil are mixtures of inorganic and organic substances, so changes may occur during storage. The objective of this work was to assess the potential for inorganic N transformations and potential gaseous losses when a soil leachate was treated in various ways and stored in glass bottles for 10 days at −20, 4 or 20°C. The treatments were natural pH of 6.3, acidification to pH 4.5, and adjustment of the salt strength to 2 M in KCl. The NH 4 +, NO 2 − and NO 3 − concentrations were enhanced and differentially labelled with 15N. After 10 days, headspaces were analysed to determine the fluxes of N 2O and N 2, and solutions were analysed for inorganic-N concentrations and their 15N enrichments. Concentrations changed least when the storage temperature was 4°C or when the ionic composition was primarily 2 M KCl. Ammonium concentrations changed little, a small significant ( P