Effective nutrient sources for plant growth on bauxite residue I. Comparing organic and inorganic fertilizers

We conducted a field experiment to evaluate alternatives to poultry manure, the normal fertilizer used for growing dust control crops and native vegetation on bauxite residue sand. We compared plant growth, nutrient uptake and residue properties after applications of poultry manure, compost, composted poultry manure and inorganic fertilizer. The compost used was prepared from green waste treated with piggery waste. Plant growth was poor under the compost and composted poultry manure treatments, which produced 0.69 and 1.11 t ha(-1) of above ground biomass, respectively. This compared with 2.43 t ha(-1) from the inorganic fertilizer treatment which had a similar biomass to the poultry manure treatment (3.00 t ha(-1)). All treatments, including poultry manure, had low foliar concentrations of some nutrients, with low levels of N, P, K, Mg, Cu and Zn found in most treatments. Of the two treatments which gave effective dust control (inorganic fertilizer and poultry manure) the most economical was inorganic fertilizer which cost A$1227 ha(-1). The high application rate of the poultry manure made it the most expensive fertilizer treatment at a cost of A$1650 ha(-1). There appeared to be no long-term benefit of using organic amendments, as organic fertilizers did not improve residue conditions (organic matter content, pH, electrical conductivity, activity of Na+ ions) compared with the inorganic fertilizer. It was concluded that inorganic fertilizer could provide a suitable, cost-effective alternative to poultry manure for growth of dust control crops, with further research required to address low levels of some nutrients.