Effects of amendments and fertilization on plant growth, nitrogen and phosphorus availability in rehabilitated highly alkaline bauxite-processing residue sand
MetadataShow full item record
The effects of organic-inorganic amendments and nitrogen-phosphorus (NP) fertilization (NH4NO3 plus Ca (H2PO4)2) on ryegrass (Lolium rigidum) growth, and nitrogen (N) and phosphorus (P) availability in highly alkaline bauxite-processing residue sand (BRS), were examined in a pot experiment. The BRS used was either unamended (control) or amended with organic (e.g. greenwaste compost and biochar) or inorganic (e.g. zeolite) materials at a rate of 10% v/v. BRS from 15 years of rehabilitation (15YRRH) was also used as the second control. NP fertilizer was applied at different rates. The experimental set up was arranged in a two factorial complete randomized design. BRS with zeolite and 15YRRH at NP fertilizer rates of 2.0 and 2.5 t/ha produced the highest dry matter, leaf N concentration and N uptake by ryegrass, which were significantly higher (P < 0.05) than the other treatments, suggesting the potential of zeolite in providing stability of applied N fertilizer in BRS. Further, BRS with biochar at NP rates 2.0 and 2.5 t/ha can also be suitable amendments as they enhance growth and also improved the N and P supplying capacity of BRS. Ryegrass leaf P concentration and P uptake were above the critical P values in the 15YRRH compared with organic-inorganic amended BRS, suggesting that time is important for better P uptake from the residue. It is concluded that zeolite and biochar combined with appropriate NP fertilizer rates can improve plant growth and provide a source of nutrients for ryegrass establishment in bauxite residue storage areas. The results need to be tested in field conditions before being advised in farming practice.
Soil Use and Management
Soil Chemistry (excl. Carbon Sequestration Science)