Black Layer

A black coloured layer within a soil which indicates poor growing conditions. It results from an anaerobic soil which has developed from a range of contributing activities. High sand content soils are particularly susceptible to black layer development.

Regular, often excessive irrigation, combined with compaction, and the build-up of organic material within a rootzone encourages the growth of certain bacteria. These bacteria produce hydrogen sulphide gas in this environment: This is harmful to turf grasses. Iron, within the soil, reacts with this gas to produce the distinct black iron sulphide layer.

Black layer is also favoured by alkaline conditions; incorrect topdressings with lots of finer particles contaminating the mixture; and also the regular use of rollers on sand surfaces for cosmetic purposes, thereby increasing compaction. A poorly drained, often waterlogged soil is produced as a result of black layer.