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Titolo:
USE OF RESIDUAL FERTILIZER N-15 IN SOIL FOR ISOTOPE-DILUTION ESTIMATES OF N-2 FIXATION BY GRAIN LEGUMES
Autore:
MCNEILL AM; PILBEAM CJ; HARRIS HC; SWIFT RS;
Indirizzi:
UNIV WESTERN AUSTRALIA,COOPERAT RES CTR LEGUMES MEDITERRANEAN AGR NEDLANDS WA 6907 AUSTRALIA UNIV READING,DEPT SOIL SCI READING RG6 6DW BERKS ENGLAND ICARDIA ALEPPO SYRIA CSIRO GLEN OSMOND SA 5064 AUSTRALIA
Titolo Testata:
Australian Journal of Agricultural Research
fascicolo: 5, volume: 49, anno: 1998,
pagine: 821 - 828
SICI:
0004-9409(1998)49:5<821:UORFNI>2.0.ZU;2-U
Fonte:
ISI
Lingua:
ENG
Soggetto:
NITROGEN-FIXATION; N-15-LABELED FERTILIZER; N2 FIXATION; PLANT; N-2-FIXATION; ENRICHMENT; CROP;
Keywords:
CHICKPEA; LENTIL; WHEAT; ROTATION;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
35
Recensione:
Indirizzi per estratti:
Citazione:
A.M. Mcneill et al., "USE OF RESIDUAL FERTILIZER N-15 IN SOIL FOR ISOTOPE-DILUTION ESTIMATES OF N-2 FIXATION BY GRAIN LEGUMES", Australian Journal of Agricultural Research, 49(5), 1998, pp. 821-828

Abstract

Estimates of the proportion of nitrogen (N) derived from the atmosphere (pN(atm)) by chickpea and lentil in the alternate phase of a cereal-legume 2-year rotation, for each of 3 seasons (1993, 1994, and 1995) in northern Syria, were obtained from isotope dilution methodology using residual fertiliser N-15 in the soil (IDres). The N-15 had been immobilised, during the year antecedent to the legume, from N-15-enrichedfertiliser which had been applied at sowing to wheat in the cereal phase of the rotation at 30 kg N/ha. For lentil in 1994, and for chickpea in 1993 and 1994, the IDres estimates of pN(atm) were compared with those obtained by using the classical N-15 isotope dilution method (ID) where N-15-enriched fertiliser (either 30 or 10 kg N/ha) was added at sowing to both the legume and non-fixing reference crops. Estimates of pN(atm) for 1994 from the 2 methodological approaches were significantly (P < 0.01) different for lentil, with ID resulting in a higher estimate than IDres (0.92 v. 0.85). For chickpea in the same season (1994) the IDres estimate was significantly higher than the ID estimate (0.88 v. 0.78) at 30 kg N/ha because the N fertiliser inhibited biological N fixation (BNF). However, using a lower fertiliser rate (10 kg N/ha) for ID the estimate of pN(atm) obtained for chickpea in 1994 was 0.91, which was slightly higher than the IDres estimate. Proportional reliance on BNF was estimated to be greater in spring than at harvest for both lentil and chickpea. The estimates of pN(atm) obtained at harvest were greatest (>0.82) for both crops in 1994 and less, but similar, for both crops (0.64-0.79) in the other 2 seasons (1993 and 1995). Although substantial amounts of residual fertiliser N were present in the soil, only a small proportion of the original fertiliser N added (<5%) was utilised by plant uptake plus any losses in the residual year,indicative of a slow remineralisation rate for the immobilised labelled N. Nevertheless, the crops in the residual year were sufficiently enriched to allow for estimation of pN(atm). The N-15 abundance, at harvest, of wheat shoots from the N-15 IDres method was similar to that of the soil nitrate and ammonium pools, suggesting that plant N uptake through the season had been from an N pool of reasonably constant enrichment. This was in contrast to wheat receiving N-15-labelled fertiliser at sowing, where the shoots at harvest had a higher N-15 abundance than the plant-available N pool, indicating a declining N-15 enrichment of plant-available N in the soil through the season. Furthermore, variability in the N-15 abundance of plant-available N with soil depth was also demonstrated to be greater where the N-15 IDres method was used, for ammonium N at least. These differences in N-15 enrichment patterns of the plant-available N pool for the 2 methods resulted in significantly different estimates for pN(atm) of lentil in 1994 but for all the other comparisons there were no major differences between estimates obtained using either ID or IDres.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 19/09/20 alle ore 10:39:44