Re-vegetating contaminated land

Recent advances, developed at the Department of Earth Sciences and Botanic Garden, University of Cambridge, UK, have lead to a new strategy for sustaining plant growth on contaminated land. This technology will enable highly polluted sites to be re-vegetated at low cost.

By using the microporous properties of natural zeolites, it is possible to grow and sustain plants on contaminated sites which in the past have not been able to support any vegetation.

In this way waste and marginal land can be used to cultivate energy crops such as oil seed rape (B.napus), ossier willow and a large number of other plants that could provide biomass for combined heating and power.

The technology is low cost and is an in-situ method that requires only surface amendment by an organo-zeolitic mixture.

This material is made by composting crushed zeolitic rock with animal or plant waste.

During composting, ammonia is generated by the microbial degradation of the organic material and stored as NH4+ ions in the zeolite pore space thus preventing lost to the atmosphere by volatilization or leaching by rain water.

In a soil environment the NH4+ becomes available for oxidation by nitrifying soil micro-organisms providing a supply of nitrate and other nutrients elements that are readily taken up by the plant.

The new research has shown that plant growth can now be sustained on sites that in the past have remained barren for tens of years or longer.

These sites can now be treated to provide a healthy top soil upon which it will be possible to establish parkland or grow “industrial” crops.

This will help overcome the potential health hazards and create a land surface that could be redeveloped in numerous ways

References

Leggo, P.J, 2000. An investigation of plant growth in an organo-zeolitic substrate and its ecological significance. Plant and Soil 219: 135-146.

Leggo, P.J and Ledésert, B 2001.Use of an organo-zeolitic fertilizer to sustain plant growth and stabilize metallurgical and mine-waste sites. Mineralogical Magazine, Vol. 65(5), 563-570.

Leggo, P.J. European Patent: EP 1 208 922 B1 Method of sustaining plant growth in toxic substrates polluted with heavy metal elements. Bulletin 2004 / 10.

Leggo, P.J., Ledésert, B and Christie, G, 2006. The role of clinoptilolite in organo-zeolitic-soil systems used for phytoremedation. Science of the Total Environment, 363(2006) 1-10.

Leggo, P.J and Ledésert, B, 2008. Organo-zeolitic-soil systems: A new approach to plant nutrition. In: Fertilizers: Properties, Applications and Effects. (Eds) L.R.Elsworth and W.O.Paley, Nova Science Publishers, Inc, New York, 223-239.

Leggo, P.J and Ledésert, B, 2009. The stimulation of nitrification in an organically enriched soil by zeolitic tuff and its effect on plant growing. Annals of Agrarian Science, 7, 3, 9-15.

Phytoremediation: Transformation and Control of Contaminants. (Eds) S.C.McCutcheon and J. L. Schnoor. Wiley-Interscience, 2003, ISBN 0-471-39435-1.