Existing direct isolation methods may seriously underestimate the actual numbers of actinophages in soil, since major ‘losses’ may be incurred during agitation, filter sterilization and, to a lesser extent, centrifugation. Two methods were devised for the isolation and enumeration of soil actinophages and were compared experimentally with two previously described methods. Numbers of up to 2 × 104 p.f.u. (g soil)−1 were detected in compost soil.

Nitrogen supply is the major limiting factor in most reclamation schemes. A fully functional nitrogen cycle is dependent on the accumulation of resident soil organic matter from which nitrogen may be released slowly by microbial decomposition. Soil nitrogen transformations including nitrification, mineralisation and immobilisation are discussed, with particular reference to nitrogen transformations in reclaimed land.

Actinophage active against both neutrophilic and acidophilic streptomycetes were isolated from a variety of soils by a specific enrichment method. No phage were detected in soils with a pH below 6·0, despite the presence of acidophilic streptomycetes in these soils. However, some phage isolated from neutral soils were able to lyse acidophilic streptomycetes at pH 5·5. Selected actinophage were shown to be stable between pH 5·5 and 9·0 in sterile soils and broth, but were rapidly inactivated at lower or higher pH values. Survival of these phage was good in neutral soils, but negligible in acidic soils. This suggested that free phage were unable to remain infective in acidic soils, thus at least partially accounting for the failure to isolate them. Acidity was shown to have variable effects on several stages of phage replication including adsorption, penetration and the length of the latent period. The latter effect was directly related to the metabolic activity of the host.

The effectiveness of nitrogen transfer from legumes to associated grasses in revegetated china clay sand wastes was evaluated.

Reduced leaching rates in sand waste produced by the china clay industry were achieved by mixing sand with micaceous residue, a secondary byproduct of kaolin extraction. Three sand/mica plots were constructed on a mica lagoon wall and a sand tip. Soil properties of the sand/mica plots and adjacent untreated sand were compared before and after ten months' revegetation and fertilisation.

The decomposition rates of a grass/clover mixture buried in revegetated china clay sand wastes of varying age and management were compared. Rates of weight loss compared favourably with those obtained by other workers on litter decomposition and were generally negatively related to C:N ratio and positively related to organic matter and total nitrogen concentration.