GREEN MOVE project: Utilization of waste rocks and mine tailings in building B-layer after soil relocation

Well-developed soil is the starting point for good cultivated land, which is a prerequisite for food production. For many years there has been a decline in cultivated areas in Norway and in recent years we have seen an increasing conflict between the conservation of topsoil and the reduction of areas for use for development and infrastructure. Although there are political goals to increase cultivated areas, the reality is that more and more productive land is disappearing. There is little land available that enables the cultivation of food grains, and 35% of the remaining arable land is bog, which is not desirable to cultivate due to the effects on the environment.

The GREEN MOVE project aims at creating methods to maintain cultivated land by sustainably moving soils from the infrastructure affected sites and reconstructing agricultural soils to alternative locations avoiding important conflicting societal interests. The project aims at proposing an informed and strategic approach to a highly ambivalent issue that may enable both sustainable development of important infrastructure as well as preservation of valuable soil resources.

One of the objectives in the GREEN MOVE project is to evaluate the potential of utilizing crushed waste rocks and other mine tailings to improve subsoil properties at new locations securing agronomic plant production. To do it we need to build knowledge on how to determine the potential of utilizing crushed waste rock and other mine tailings to improve the susoil layers.

Selected waste rock materials from ongoing infrastructure projects (e.g. tunnel masses) and waste rock material from Norwegian mining industry will be characterized by use of XRD, XRF and SEM to analyze mineral content and surface characteristics. Grained rock fractions of < 2mm will then be used in simple column leaching experiments in the laboratory to determine lability of chemical components from the waste rock materials. The potential weathering rate of the different waste rock materials will also be explored in the laboratory when exposed to and being in equilibrium with still water and weak organic acids (mimicking plant root exudates). The grained fraction < 2 mm of selected waste rock materials will then be mixed by soil and/or peat and used as growth medium for plants in simple greenhouse experiments as well as in field soil lysimeters. The most promising waste rock materials will finally be used to build up soil B-horizons in field experiments with agronomic plant production. In the soil B horizon the waste mineral material will be mixed by soil and/or organic matter. Prior to the field experiments a careful selection of texture classes of the waste rocks needs to be done to secure the soil porosity, pore size distribution, permeability and water holding capacity. In the field experiments soil quality parameters and yield will be measured.