Individual study: Factors affecting nitrogen fixation by white clover Trifolium repens on colliery spoil at Thorne, South Yorkshire, England
Palmer J.P. & Iverson L.R. (1983) Factors affecting nitrogen fixation by white clover (Trifolium repens) on colliery spoil. Journal of Applied Ecology, 20, 287-301
This study described here is part of a wider research project investigating the effectiveness of different forms of nitrogen supply to colliery spoil in order to promote revegetation. This summary describes the fluctuations in nitrogen fixation by white clover Trifolium repens under different fertiliser and grass sowing treatmentson colliery spoil at Thorne in South Yorkshire, northeast England.
Experimental design and data collection: Field measurements were carried out at approximately weekly intervals between 22 May and 24 November 1980. The trial was of a randomized block split plot design incorporating four blocks (replicates), 12 treatments (six nitrogen sources in combination with high and low phosphate levels) and four subplots (grass cultivars) applied in 1975.
Sampling was confined to perennial rye-grass Lolium perenne cultivated variety (cv.) S23, red fescue Festuca rubra cv. S59 and cock’s-foot Dactylis glomerata cv. S37, plots of white clover Trifolium repens cv. Sl00 and ammonium sulphate treatments at high and low phosphate levels. All plots were cut to about 5 cm on 6 June and 9 September 1980 (harvests 1 and 2) and the herbage removed.
The nitrogen fixation of white clover which established was measured (acetylene reduction technique) at weekly intervals between May and November. Spoil chemical characteristics, moisture and temperature, sunshine hours, air temperature and rainfall were monitored.
Residual spoil phosphate levels from two rates of phosphate fertilizer applied 5 years previously affected N fixation, with high residual phosphate resulting in higher fixation. These differences were attributed to higher spoil nitrogen on the high phosphate addition plots. Sunshine, higher spoil temperatures and adequate moisture were positively associated with N fixation over the sampling period. Estimated annual nitrogen inputs by clover fixation were 146-167 kg N/ha on high phosphate plots and 90-103 kg N/ha on low phosphate plots. No nitrogen fixation was detected on plots without white clover. Cutting decreased N fixation.
Conclusions: Due to cost, options open to reclamation practitioners to maximize nitrogen fixation potential on colliery spoil restoration sites are limited. Maintaining available phosphate supply (at sites where low) is considered crucial. This study also indicates that adequate moisture levels are likewise key for N fixation to be maintained at a satisfactory level on colliery spoils.
Note: The compilation and addition of this summary was funded by the Journal of Applied Ecology (BES). If using or referring to this published study, please read and quote the original paper, this can be viewed at: http://links.jstor.org/sici?sici=0021-8901%28198304%2920%3A1%3C287%3AFANFBW%3E2.0.CO%3B2-6