Uptake of foliar-applied urea by winter wheat (Triticum aestivum): The influence of application time and the use of a new 15N technique
✍ Scribed by David S Powlson; Paul R Poulton; Niels E Møller; Michael V Hewitt; Alexander Penny; David S Jenkinson
- Publisher
- John Wiley and Sons
- Year
- 1989
- Tongue
- English
- Weight
- 675 KB
- Volume
- 48
- Category
- Article
- ISSN
- 0022-5142
No coin nor oath required. For personal study only.
✦ Synopsis
A new 15N technique (termed the negative discard method) for measuring recovery of foliar-applied N by crops in the field is described. '5N-labelled fertiliser solution is sprayed on to a small area of crop, using a hand sprayer, while the surrounding area is sprayed with unlabelled N at the same rate. An area considerably larger than that given I5N is harvested with a small-plot combine-harvester, and crop recovery of foliar-applied N is calculated jkom the ' N enrichment of the resulting sample containing a mixture of labelled and unlabelled material.
N-labelled urea solution sprayed on to winter wheat (Triticum aestivum L cv Avalon) at six dijfirent times from growth stage 39 (3 weeks before anthesis) to growth stage 73 (2 weeks after anthesis). Each treatment of 40 kg N ha-' was divided into two equal portions, the second being applied 1-2 days after the first, to minimise the risk of leaf damage. The crop had earlier received 210 k g N ha-', as 'Nitro-Chalk', in spring (50 kg ha-' at growth stage 22 and 160 kg ha-' at growth stage 31) which was more than suficient to achieve maximum grain yield. At harvest, 70 % of the foliar-applied N given at anthesis (growth stage 65) was recovered in the above-ground crop, including 64 % in grain. The proportion of labelled N recovered in the grain (92% of that in the above-ground crop) was slightly greater than with soilapplied N given earlier in the growing season. Recovery of foliar-applied N The technique was used to measure recovery of N from