Individual study: Growth of leguminous species to promote nitrogen accumulation on mine spoil at Maypole Tip, Abram, Greater Manchester, England
Jefferies R.A., Bradshaw A.D. & Putwain P.D. (1981) Growth, nitrogen accumulation and nitrogen transfer by legume species established on mine spoils. Journal of Applied Ecology, 18, 945-956
Nitrogen deficiency is often limits plant growth on many types of mine and mineral spoils. One method of overcoming this is to use legume species which are able to accumulate nitrogen in the substrate. The growth, nitrogen accumulation and nitrogen transfer to a companion grass species was compared for 12 legume species on mine spoil at Maypole Tip, Greater Manchester (National Grid ref. SD 613019), northwest England.
Study site: In August 1977, spoil was amended with ground dolomitic limestone (15 t/ha) incorporated to a depth of 30 cm by deep-ripping tines using heavy machinery. The seed bed was prepared by harrowing and addition of nitrogen (N), phosphorus (P) and potassium (K) were applied at rates of 30 kg N (ammonium nitrate), 40 kg P (superphosphate) and 40 kg K/ha (potassium sulphate) fertilizers.
Experimental design: Twelve legume species were sown in a randomized block design with three replicates in 1 x 0.5 m plots. Legume seeds were inoculated with the appropriate Rhizobium strain to improve establishment and sown at a rate of 50 kg/ha. Bent-grass Agrostis castellana cv.‘Highland’ was sown at 30 kg/ha with each legume and in monoculture at 80 kg/ha. The legume species (natives and non-natives) sown were:
Biennials: black medick Medicago lupulina, ribbed melilot Melilotus officinalis;
Perennials: crown vetch Coronilla varia, broom Cytisus scoparius, lucerne Medicago sativa, bird’s-foot trefoil Lotus corniculatus, greater bird's-foot trefoil L.uliginosus, lupine Lupinus perennis, Alsike clover Trifolium hybridum, red clover T.pratense, white clover T.repens, gorse Ulex europaeus.
Harvesting: Vegetation was sampled in October 1978 and May 1979, 14 and 22 months after sowing. At each harvest a subsample of 625 cm² was clipped to a height of 2-3 cm. Different areas of the plots were sampled at each harvest. The material was dried and separated into legume and Agrostis and weighed. Plant material could not be separated well from the soil thus analysis of total soil organic nitrogen was problematic. Total plant nitrogen was determined.
At first harvest M.lupulina was the most productive species (17 t dry wt/ha) but it declined at the second harvest as seedlings failed to establish amongst the Agrostis. Of the perennials, M.sativa and L.corniculatus were most productive (9.6 and 8.6 t dry wt/ha respectively). T.repens yield was low (4.2 t dry wt/ha). At the second harvest M.sativa and L.perennis were the highest yielding species (18 and 14.7 t dry wt/ha respectively). Yields of the other herbaceous perennial legumes tended to decline at the second harvest. The two woody shrubs, broom and gorse established slowly. Broom showed a small increase in biomass at the second harvest, but all gorse died between the first and second harvest.
No legume species affected Agrostis yield at the first harvest. The grass monoculture became chlorotic by the second harvest and biomass declined. In contrast biomass of Agrostis grown with T.repens, L.uliginosus and M.officinalis increased and were significantly greater than the monoculture. T.repens was the most effective (Agrostis biomass almost 5 times greater than the monoculture).
N content of legume shoots was similar to the pattern of dry matter production. Agrostis N content was not significantly affected by any legume at first harvest but differences were apparent at the second. The difference was greatest when in association with T.repens, grass shoots having a N content of 80 kg/ha, compared with 4 kg/ha in the monoculture.
Conclusions: Of the legumes trialed, several perennials effectively established on the mine waste. N transfer from legumes to the companion grass was apparent and was greatest using T.repens. In the absence of legumes, the grass biomass declined.
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%28198112%2918%3A3%3C945%3AGNAANT%3E2.0.CO%3B2-2