Growth of rye grass and clover in artificial topsoils: a case study

Abstract

The Latrobe Valley region of eastern Victoria houses three major mines which burns lignite for power generation and is referred to as the power house of Victoria. These mines are looking for sustainable ways to manage their waste and achieve successful mine rehabilitation. One of the problems to be addressed for attaining successful mine rehabilitation is the scarcity of topsoils for vegetation cover. The possible solution for overcoming this problem is the use of artificial topsoils (ATS) developed using waste streams, i.e. overburden, interseam brown coal, ash from the onsite powerplant and nearby paper industry waste i.e. effluent sewage recovery (ESR). Field lysimeter experiments with ATS proved that there is no leachate toxicity but the plant available nutrients were relatively low. Hence, clear understanding of ATS as a substrate for vegetation should be examined before applying it in the field. In a recent study, we tested the growth of ryegrass, clover and ryegrass + clover mixture in ATS with and without addition of nitrogen-phosphorouspotassium fertilizer (NPK) in a greenhouse experiment compared to control, i.e. overburden, overburden + ash, natural topsoil. The results after 12 weeks indicate that the height of ryegrass in ATS with NPK is 2.7 cm higher than the height of ryegrass in natural topsoil and is 16 and 17 cm higher than the growth of ryegrass in overburden and overburden + ash mixture respectively. The height of clover in ATS with NPK is 1 cm higher than the clover grown in natural topsoil and around 5 cm more than the height of clover in overburden and overburden + ash mixture. The germination in ATS was slightly delayed as compared to natural topsoil due to higher exchangeable sodium percent in soil, but the presence of NPK in ATS later aided in survival and growth of grass and clover. The initial results from these experiments show that ATS with addition of NPK can be a potential solution in mine rehabilitation and can be used as a substrate for revegetation.

From spoil to soil: utilising waste materials to create soils for mine rehabilitation

“…The addition of anaerobically digested paper mill waste, called effluent sewage recovery (ESR), and waste lignite from the mine (BC) has increased the organic matter and nutrient content of the soils. A lysimeter field study deemed these soils safe for mine rehabilitation, and further greenhouse study (Mundodi 2020;Mundodi et al 2019) showed that they provide a substrate suitable for plant growth, although relatively high salinity has delayed germination of clover. Table 1 summarises all the substrates used in the present study and their basic properties.…”