Denitrification losses of nitrogen fertilizer applied to winter wheat following ley and arable rotations as estimated by acetylene inhibition and 15N balance

A - Papers appearing in refereed journals

Goulding, K. W. T., Webster, C. P., Powlson, D. S. and Poulton, P. R. 1993. Denitrification losses of nitrogen fertilizer applied to winter wheat following ley and arable rotations as estimated by acetylene inhibition and 15N balance. Journal of Soil Science. 44 (1), pp. 63-72.

AuthorsGoulding, K. W. T., Webster, C. P., Powlson, D. S. and Poulton, P. R.
Abstract

We studied the fate of 222 kg N ha-1 applied in spring as (KNO3)-N-15 to winter wheat test crops which followed either continuous arable cropping (Arable) or a rotation in which a 3-year grass/clover ley preceded the wheat (Ley). Denitrification losses (measured by an acetylene-inhibition method) of over 1 kg N ha-1 d-1 were measured for short periods following heavy rain in mid-May. However the generally dry and cool weather resulted in accumulated losses by denitrification between fertilizer application and anthesis equivalent to only 5.3% and 3.6% (+/-2%) of the applied N for the arable and ley treatments respectively. The smaller loss from the lev was despite this treatment containing more inorganic N and available carbon. N-15 balance indicated that, at anthesis, 1.5% and 11.5% (+/-7%) of the labelled N was lost from the arable and ley treatments respectively. Given the precision of the N-15 and the acetylene-inhibition methods, the results are not significantly different. However, the larger difference between methods for losses from the ley treatment may be an underestimate because N-15 balance does not measure losses of unlabelled N. These were probably very small on the arable treatment but could have increased total N loss by 25% to c. 32 kg ha-1 on the ley treatment compared with the 8 kg ha-1 measured as denitrificd. Such a large difference is unlikely to be an error but was probably due to ammonia volatilization from this crop which was severely infected by mildew. The results were thus a poor test of the acetylene-inhibition method, but revealed another loss process which could be significant in some situations.

KeywordsSoil Science
Year of Publication1993
JournalJournal of Soil Science
Journal citation44 (1), pp. 63-72
Open accessPublished as non-open access
Funder project or code920
221
ISSN00224588
0022-4588
PublisherWiley
British Society of Soil Science (BSSS)

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