Forms of sulphur in sheep excreta and their fate after application on to pasture soil
✍ Scribed by Prue H Williams; Richard J Haynes
- Book ID
- 102925200
- Publisher
- John Wiley and Sons
- Year
- 1993
- Tongue
- English
- Weight
- 724 KB
- Volume
- 62
- Category
- Article
- ISSN
- 0022-5142
No coin nor oath required. For personal study only.
✦ Synopsis
Abstract
Sheep were fed ^35^S‐labelled grass/clover herbage and the excreta was collected. About 74% of excretal S was in the form of urine and the remainder was in dung. Sulphate‐S accounted for 74% of the urine S and the remainder was in Hi‐reducible form. In dung, 80% of the S was C‐bonded organic S and 20% was present as sulphate‐S.
^35^S‐labelled dung was applied to undisturbed pasture microplots and the degradation and S release followed over a 9 month period under glasshouse conditions. During the first 34 days about 24% of ^35^S was leached from the dung, mainly as sulphate‐S and possibly some labile organic S. The C‐bonded S in the dung was notably resistant to mineralisation. Only 14% of the applied ^35^S was recovered by pasture plants.
^35^S‐labelled urine with either a high (1130 mg S litre^−1^) or a low S concentration (280 mg S litre^−1^) was applied in the field and its fate followed over a 10 month period. During the experiment 57 and 79% of the applied ^35^S was recovered in pasture herbage in the high and low urine treatments, respectively. ^35^S was also incorporated into soil organic matter and this reached a peak about 120 days after urine application when 52 and 30% of applied S had been incorporated in the high and low urine S treatments, respectively. With time, these levels declined as about 50% of the organic ^35^S was mineralised and subsequently absorbed by the pasture plants. The results demonstrate that excreted S is recycled rapidly in pasture soils when it originates from urine. However, the bulk of S in dung appears to be relatively inert at least over a 9 month period.