ISSN:
1573-0867
Keywords:
15N
;
nitrogen efficiency
;
microplots
;
ammonium nitrate
;
urea
;
ryegrass
Source:
Springer Online Journal Archives 1860-2000
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Abstract Confined microplots were used to study the fate of15N-labelled ammonium nitrate and urea when applied to ryegrass in spring at 3 lowland sites (S1, S2 and S3). Urea and differentially and doubly labelled ammonium nitrate were applied at 50 and 100 kg N ha−1. The % utilization of the15N-labelled fertilizer was measured in 3 cuts of herbage and in soil to a depth of 15 cm (soil0–15). Over all rates, forms and sites, the % utilization values for cuts 1, 2, 3 and soil0–15 were 52.4, 5.3, 2.4 and 16.0% respectively. The % utilization of15N in herbage varied little as the rate of application increased but the % utilization in the soil0–15 decreased as the rate of application increased. The total % utilization values in herbage plus soil0–15 indicated that losses of N increased from 12 to 25 kg N ha−1 as the rate of N application was increased from 50 to 100 kg N ha−1. The total % utilization values in herbage plus soil0–15 over both rates of fertilizer N application were 84.1, 80.8 and 81.0% for urea compared with 74.9, 72.5 and 74.4% for all ammonium nitrate forms at S1, S2 and S3 respectively. Within ammonium nitrate forms, the total % utilization values in herbage plus soil0–15 over both rates and all sites were 76.7, 69.4 and 75.7% for15NH4NO3, NH4 15NO3 and15NH4 15NO3 respectively. The utilization of the nitrate moiety of ammonium nitrate was lower than the utilization of the ammonium moiety. The distribution of labelled fertilizer between herbage and soil0–15 varied with soil type. As the total utilization of labelled fertilizer was similar at all sites the cumulative losses due to denitrification and downward movement appeared to account for approximately equal amounts of N at each site.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01055399
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