ISSN:
1573-5036
Schlagwort(e):
isotope dilution
;
15N
;
nitrogen
;
nitrogen fixation
;
nitrogen transfer
;
ryegrass
;
white clover
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
Notizen:
Abstract The stable isotope15N is particularly valuable in the field for measuring N fixation by isotope dilution. At the same time other soil-plant processes can be studied, including15N recovery, and nitrogen transfer between clover and grass. Three contrasting sites and soils were used in the present work: a lowland soil, an upland soil, and an upland peat. Nitrogen fixation varied from 12 gm−2 on lowland soil to 2.7 gm−2 on upland peat. Most N transfer occurred on upland soil (4.2 gm−2) which, added to nitrogen fixed, made a total of 8.7 gm2 input during summer 1985.15N recovery for the whole experiment was small, around 25%. Measurement of dead and dying leaves, stubble and roots, suggests that plant organ death is the first stage in N transfer from white clover to ryegrass, through the decomposer cycle. Decomposition was fastest on lowland soils, slowest on peat. On lowland soil this decomposer nitrogen is apparently subverted before transfer, probably by soil microbes. Variations in natural abundance of15N in plants were found in the two species on the different soils. These might be used to measure nitrogen fixation without adding isotope, but the need for many replicates and repeat samples would limit throughput.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF02140002
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