Concurrent measurements of net mineralization, nitrification, denitrification and leaching from field incubated soil cores

• Published in: Biology and fertility of soils 1998-03, Vol.26 (4), p.323-330
• Main Authors: Hatch, D.J, Jarvis, S.C, Parkinson, R.J
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; biogeochemical cycles; Biological and medical sciences; brown earths; Chemical, physicochemical, biochemical and biological properties; correlation; denitrification; drained conditions; field experimentation; Fundamental and applied biological sciences. Psychology; impeded drainage; incubation; leaching; measurement; mineralization; nitrate nitrogen; nitrification; nitrogen; Organic matter; Physics, chemistry, biochemistry and biology of agricultural and forest soils; Soil science; stagnogleys; transformation
• ISSN: 0178-2762; 1432-0789
• DOI: 10.1007/s003740050383

An improved method is described for incubating intact soil cores in the field, which permits concurrent measurement of net mineralization, nitrification, denitrification and leaching. Cores were enclosed in PVC tubes with minimal disturbance to the physical state or to the natural cycles of wetting/drying, soil temperature and aeration during an incubation lasting 4-5 days. An example of the application of the method is given in which soils with contrasting drainage characteristics were compared. Over a 64-day experimental period, 58% of the mineralized nitrogen (N) in a freely drained soil was nitrified and 36% of the nitrate-N (NO(3-)-N) was dentrified. In a poorly drained soil, 72% of the mineralized N was nitrified and 63% of the NO(3-)-N was denitrified. In both soil types, 18% of the remaining NO(3-)-N was leached. Rates of nitrification were significantly correlated with net mineralization (r2=0.41 and 0.52) and also closely correlated with denitrification (r2=0.67 and 0.68) in the freely and poorly drained soils, respectively. Independent measurements of these processes, using alternative techniques (for the same period), compared favourably with measurements obtained with the improved incubation method. Adoption of this method has a number of advantages with respect to field net N mineralization, and also allows interpretation of the impact this may have on other N transformation processes.