Some soil factors constraining buffel grass (Cenchrus ciliaris L.) seedling growth rate across a range of acid red Kandosols in Queensland, Australia

Buffel grass ( Cenchrus ciliaris L.) has passionate grazing industry advocates and biodiversity conservation detractors around the world due to its ability to readily establish and spread on certain soil types. A more detailed understanding of what soil factors influence the success of seedling establishment will offer guidance to anyone wishing to either encourage or discourage buffel grass establishment in a particular area. Twenty soils from land types where buffel grass had a varied history of successful establishment and persistence in south western Queensland, Australia were assessed in a pot trial for their influence on early seedling growth rate of buffel grass. Some currently had buffel grass growing there. Aspects of the chemistry of each soil were compared against the rate of seedling growth of buffel grass cv. Biloela that was sown with or without a phosphate coating on the seed. Available soil phosphorus had a major influence on seedling growth in the absence of a phosphate fertiliser coating, but levels of other factors such as exchangeable aluminium and calcium were also critical. Several multiple regression equations with differing soil parameters included proved equally good at predicting buffel seedling growth but they did not greatly improve on the strong correlation with available soil phosphorus. This seemed due to the interchangeability amongst soil pH, cation exchange capacity and degree of clay as controlling factors, over and above available phosphorus. Thus, where available soil phosphorus is marginal for rapid buffel seedling growth, soil pH, exchangeable aluminium and total exchangeable cation levels could have similar importance in determining whether buffel grass colonised or failed to gain a foothold in that area.