ISSN:
1432-0789
Keywords:
Biologically fixed N
;
Crop rotations
;
N benefit
;
N sparing
;
N transfer
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Geosciences
,
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Summary A crop of barley was grown on plots which had previously supported pure stands of lupins, canola, ryegrass, and wheat. The plots were labelled with 15N-enriched fertilizers at the time of sowing of the antecedent crops. The crop of lupins, which derived 79% of its N from symbiotic N2 fixation at physiological maturity, conferred an N benefit to barley of 3.4 g N m-2 when compared to barley following wheat. Lupins used less fertilizer N and less unlabelled soil N compared to the other crops, but the ratios of these sources of N in the plant tops were similar. The apparent sparing of soil+fertilizer N under lupins compared with wheat was 13.6 g N m-2, which was much larger than the measured N benefit. Barley following lupins was less enriched in 15N compared to barley following wheat, and the measured isotope dilution was used to estimate the proportion of barley N derived from biologically fixed N in the lupin residues. This in turn enabled the N benefit to be partitioned between the uptake of spared N and the uptake of fixed N derived from the mineralization of legume residues. Spared N and fixed N contributed in approximately equal proportions to the N benefit measured in barley following lupins compared to barley following wheat.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00336286
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