Helping grassland plants establish and grow at a former sand mine

June 21, 2019

Mine restoration

Photo credit (cropped): Jan Mallander from Pixabay 

 

Extraction of aggregate for construction of buildings, dams, and other infrastructure is an important industry worldwide especially since use of aggregate is growing, particularly in developing countries. Actively restoring aggregate mine sites when they become inactive can be necessary due to extreme growing conditions (e.g., very low soil nutrients).

 

In southern Ontario, sand plain prairie ecosystems have declined due to a variety of factors and engaging in restoration using prairie plant species presents an opportunity for conservation. Ohsowski et al. (2018) conducted a restoration study at a former sand mine site near Port Rowan, Ontario where they tested three different types of soil amendments that can help plants establish and grow.

 

For their study, Ohsowski et al. (2018) selected eight grassland plants found in Ontario. Plants were either grown in greenhouses before transplanting to experimental plots at the mine site (as plant plugs) or seeds were planted directly at the site in a separate set of plots. Amendment treatments consisted of different levels and combinations of biochar, compost, and/or arbuscular mycorrhizal fungi (AMF). At designated time points during the study, colonization of plant roots by AMF, soil nutrients and plant biomass were quantified for the plots that had received plant plugs whereas plant cover was estimated at plots where seeds had been planted.  

 

As expected, the researchers discovered that applying either biochar or AMF alone did not benefit plant growth while applying compost alone did. This is because the compost provided an essential source of carbon and nutrients to the depleted soil. As far as amendment combinations, compost plus biochar was most beneficial to plant growth in the plant plug trials whereas compost plus AMF inoculation resulted in the greatest plant cover in the seed application trials.

 

The value of this study to land managers is two-fold: 1) facilitate the successful restoration of sand pit mines and, 2) aid in the conservation of sand plain prairie ecosystems in Ontario.

 

Read the full article (journal subscription required):

https://onlinelibrary.wiley.com/doi/abs/10.1111/rec.12528

 

Reference:

Ohsowski BM, Dunfield K, Klironomos JN, Hart MM. 2018. Plant response to biochar, compost, and mycorrhizal fungal amendments in post-mine sandpits. Restoration Ecology. 26(1):63-72.