Long-term consequences of topsoil mining on select biological and physical characteristics of two New Zealand loessial soils under grazed pasture
✍ Scribed by P. B. S. Hart; J. A. August; A. W. West
- Book ID
- 102927290
- Publisher
- John Wiley and Sons
- Year
- 1989
- Tongue
- English
- Weight
- 830 KB
- Volume
- 1
- Category
- Article
- ISSN
- 1085-3278
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✦ Synopsis
Soil chemical, biochemical, biological and structural properties were measured in two New Zealand loessial soils that were topsoil-mined 10 and 25 years ago respectively. Measurements at the 10-year site were compared to some earlier measurements made at this site and the data combined in a chronological sequence for analysis. Topsoil mining had a large, detrimental impact on the soil microbial biomass, the earthworm populations, easily mineralizable N and soil enzyme activities. However, most of these properties substantially recovered, to 80-90 per cent of the levels in unmined soils, within 10-25 years of restoration under pasture. In contrast, while total soil C and N were less affected by topsoil mining, their recovery was much slower. Stabilities of macro-aggregates of soil had fully recovered within 10-25 years after topsoil mining. The apparent changes in all the measured properties between 10 and 25 years of restoration were small in comparison with changes between 0-10 years of restoration after topsoil mining. The t o t a r c content of both soils under pasture appeared unlikely to attain the levels present in unmined soils. In soils undergoing restoration, the ratio of microbial C/total soil C may be a useful index of soil 'biological stability'. Sulphatase activity may reflect the recovery of pasture production.