
TY  - JOUR
A1  - Ledgard, SF 
A1  - Freney, JR 
A1  - Simpson, JR 
T1  - Variations in natural enrichment of <sup>15</sup>N in the profiles of some Australian pasture soils
JF  - Soil Research
JO  - Soil Res.
Y1  - 1984
VL  - 22
IS  - 2
SP  - 155
EP  - 164
KW  - 
UR  - https://doi.org/10.1071/SR9840155 
N2  - Variability in the natural enrichment of 15N in total nitrogen (N) and several N fractions was examined for profiles of pasture soils differing in parent material and period under Trifolium subterraneum. The natural enrichment of 15N in the total N of surface soils (0-5 cm) within a 400 km2 catchment ranged from 2.55 to 6.79¿(expressed as ä15N with respect to atmospheric N2). There was no relationship with parent material, period under T. subterraneum or concentration of total N in the soil. In one soil, lateral variations in ä15N over a 12 m2 grid were within the range of 5.01 to 7.95¿. The ä15N of total soil N always increased with depth in the soil profiles. This was associated with an increase in the stable clay-sized humus fraction, which had a higher ä15N than the less humified organic N in sand and silt-sized fractions. One soil was separated into four depth layers in which ä15N in the inorganic N, mineralizable N, plant-extractable N and total soil N were determined. The first three parameters all had lower ä15N values than the total soil N. The ä15N of total N increased with soil depth, whereas there was no change with depth in the other three parameters. 
ER  -

