Effect of application of bauxite residue (red mud) to very sandy soils on subterranean clover yield and P response

Abstract

Bauxite residue (red mud) is the byproduct from treatment of crushed bauxite with caustic soda to produce alumina. When dried the residue is alkaline and has a high capacity to retain phosphorus (P). The residue is added to pastures on acidic sandy soils to increase the capacity of the soils to retain P so as to reduce leaching of P into waterways and so reduce eutrophication of the waterways. This paper examines how red mud influences the effectiveness of P from single superphosphate for producing subterranean clover (Trifolium subterraneum) dry herbage, in the year of application and in the years after application (residual value). Red mud was applied at 0, 2, 5, 10, 20, and 40 t/ha and the P was applied at 0, 5, 10, 20, 40, 80, and 160 kg P/ha. In the year of application and the year after application of red mud, dry matter yields were doubled on the soil treated with 20 t/ha of red mud compared with the untreated control. Improvements in production were initially greater in the red mud treatments than in the lime treatment (2 t lime/ha). Red mud increased the maximum yield plateau for P applied in current and previous years. When P was applied to freshly applied red mud, more P needed to be applied to produce the same yield as the amount of red mud applied increased. Red mud increased soil pH, and the increases in yield are attributed to removing low soil pH as a constraint to pasture production. This initial need for higher amounts of fertiliser P when increasing amounts of red mud were applied may be due to increased P sorption caused by increased precipitation of applied P when the fertiliser was in close contact with the freshly alkaline red mud. When P was freshly applied to red mud that had been applied to the soil 12 months ago, yield response and P content increased. This was attributed to the reduction in sorption of P due to red mud being neutralised by the soil and because sorption of P already present in the soil reduced the capacity of the red mud to sorb freshly applied fertiliser P. Residues of P in the soil and pH were also increased with application of red mud. In the years after application of red mud and lime, relative to P applied to nil red mud and nil lime treatment, the effectiveness of fertiliser P applied to the red mud and lime treatments increased. This was so as determined using plant yield, P concentration in plant tissue, and soil P test.

Red mud as an amendment for pollutants in solid and liquid phases

“…In the field extractable fractions of Cd, Pb, and Zn were reduced by up to 96%, 99%, and 99%, respectively in amended soils. Apart from immobilizing heavy metals in contaminated soils, red mud can reduce phosphorus leaching effectively (Summers et al, 1996b(Summers et al, , 2001, improve pasture growth (Summers et al, 1996a) and ameliorate soil acidity (Snars et al, 2004).…”

Guiding BMP adoption to improve water quality in various estuarine ecosystems in Western Australia

“…Therefore, where possible locally derived data on costs and effectiveness should be used to evaluate BMPs in a watershed context. An alkaline residue from bauxite processing (AlkaloamY) has significant P retention capacity and provides production benefits (Summers et al 2001). The capacity of AlkaloamY to reduce P loss ranges between 30 and 60% depending on application rate and is expected to require replacement about every 10 years.…”

Behaviour and dynamics of di-ammonium phosphate in bauxite processing residue sand in Western Australia—II. Phosphorus fractions and availability

“…Red mud contains a high percentage of sesquioxides and consequently exhibits a very high P retention capacity (Snars et al 2004). Application of red mud to sandy soils has been shown to increase P retention and reduce P leaching (Vlaho et al 1989;Summers et al 1996;Summers et al 2001). On the other hand, the chemical properties of residue mud may in fact reduce plant available P in the soil and plant uptake (Snars et al 2004).…”