Productivity of Cynodon dactylon (bermudagrass) grown on copper and nickel mine tailings amended with sewage sludge

I.A. Legwaila, B. Chunga, T. Mathowa
This plant trial project was conducted at the Botswana University of Agriculture and Natural Resources, Gaborone to establish the concentration of sewage sludge that is necessary to improve the BCL Limited mine copper and nickel mine tailings to support plant life. Cynodon dactylon (L.) Pers. was used as a model plant to record its productivity when growing in the mine tailings mixed with varying amounts of sewage sludge at 0, 104, 312, 624 and 936 t ha‑1. These quantities were mixed with 40 kg of mine tailing resulting in five treatments. Each of the treatments was replicated three times. The mixtures were then placed into 10-L polyethylene bags in which grass seeds were planted. All treatments had emergence within two weeks but the first three failed within a week. For the last two treatments, data were collected fortnightly over 16 weeks. Different parameters were measured including grass height, clippings fresh weight, turf density, colour and root fresh weight. It was found that the BCL mine tailings have very low pH and cannot support plant life with little or no sewage sludge. It was also found that sewage sludge could successfully ameliorate BCL mine tailings when used at a rate of 624 t ha‑1 or higher. However, there was no significant difference caused by addition of 936 t ha‑1 of sludge. It is therefore recommended that a concentration of between 600 and 650 t ha‑1 can be sufficient to amend BCL mine tailings and others of similar characteristics and under climatic conditions that are similar to Gaborone, Botswana.
Legwaila, I.A., Chunga, B. and Mathowa, T. (2020). Productivity of Cynodon dactylon (bermudagrass) grown on copper and nickel mine tailings amended with sewage sludge. Acta Hortic. 1279, 147-152
DOI: 10.17660/ActaHortic.2020.1279.22
mine reclamation, re-vegetation, compost, organic matter, ameliorate

Acta Horticulturae