FATE OF N-15-LABELED NITROGEN-FERTILIZER APPLIED TO KIWIFRUIT (ACTINIDIA-DELICIOSA) VINES .1. N-15 RECOVERY IN PLANT AND SOIL

The fate of N-15-labelled ammonium fertilizer applied once to six-year-old field-grown kiwifruit (Actinidia deliciosa 'Hayward') vines was measured over three years. The three main treatments were nitrogen (N) applied singularly at 100 or 200 kg N ha-1 in early spring (two weeks before bud...

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Bibliographic Details
Published in:Plant and soil 1992-11, Vol.147 (1), p.49-57
Main Authors: LEDGARD, SF, SMITH, GS, SPROSEN, MS
Format: Article
Language:English
Subjects:
Agriculture
Agronomy
Life Sciences & Biomedicine
Plant Sciences
Science & Technology
Soil Science
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Summary:The fate of N-15-labelled ammonium fertilizer applied once to six-year-old field-grown kiwifruit (Actinidia deliciosa 'Hayward') vines was measured over three years. The three main treatments were nitrogen (N) applied singularly at 100 or 200 kg N ha-1 in early spring (two weeks before bud burst) or split with 100 kg N ha-1 (unlabelled) in early spring and 100 kg N ha-1 (N-15-labelled) ten weeks later. All N treatments were applied to vines with a history of either 50 or 200 kg N ha-1 vr-1. For three years after N-15 application, components of the vines and soil (0-600 mm depth) were sampled at harvest in late autumn and the N and N-15 contents determined. By the first harvest, all plant uptake of N-15 had occurred and this represented 48-53% of the N-15 applied. There was no significant effect of current N fertilizer treatment or of N history on N-15 recovery by vines. Removal of N-15 in harvested fruit was small at 5-6% in the first year and 8% over 3 years. After 2-3 years, most plant N-15 occurred in the roots and this component declined only slowly over time. In contrast, there was a large temporal decline in N-15 in above-ground plant components due to the annual 'removal' in leaf fall and pruning. An associated experiment showed that when N-15-labelled prunings and leaves were mulched and returned to the soil, only about 9% was recovered by plants within 2 years. Almost all remaining mulched material had been immobilised into the soil organic N. In all treatments, about 20% of the added N-15 remained in soil at the first harvest. This was almost entirely in organic fractions (
ISSN:0032-079X
1573-5036
DOI:10.1007/BF00009370