ISSN:
1432-0789
Schlagwort(e):
Denitrification
;
Acetylen inhibition technique
;
15N technique
;
Organic residues
;
Mineral fertilization
;
Irrigation
;
Temperate climate
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Biologie
,
Geologie und Paläontologie
,
Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
Notizen:
Summary Denitrification N losses can be determined by three methods. The first is by estimating the non-recovery of 15 N-labelled compounds (15N-balance method). Using this method, denitrification losses are deduced from the balance of an N budged (15N-labeled fertilizer), having accounted for transformations in soil, plant uptake, and leaching losses. The evolution of gaseous N from native soil N is not taken into account by this procedure. Studies on arable land with annual crops in the temperate zone have shown that of the fertilizer N applied, about 20–500% (10–70 kg N* ha−1) is not recovered at the end of the growth period. The second method of determining denitrification N losses is by in situ field measurement of 15 N 2 and 15 N 2 O production. Under this procedure, 15N-enriched N is applied to a plot and the denitrification N losses are determined by covering the soil. The method allows a quantitative estimate of the relative contributions to the emitted gas by both the original enriched source and the native soil N. N-evolution rates measured on arable land under a temperate climate are approximately the same order of magnitude as the N losses estimated by the non-recovery of 15 N method. The third measuring procedure is based on the acetylene inhibition phenomenon. This principle uses the inhibition of bacterial N2O reduction to N2 in the presence of acetylene (C2H2). The methoddetermines the denitrification of all NO3 −-N irrespective of its source. Measurements on classical crop production systems show maximum N losses in the temperate climate of about 20–30 kg N* ha−1 during the growth period of annual crops. A similar level of denitrification is estimated for grassland sites under the same climate. In the subtropics (mediterranean climate with hot summers and mild winters), from both intensively cultivated arable land and grassland sites, N losses may exceed 200 kg* ha−1 year−1. Without the use of irrigation the denitrification flux is negligible in spite of the high temperatures in this climate.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF00266482
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