THE ROLE OF SOIL HEALTH AND FERTILITY IN RECLAIMING MINED PEATLAND AREAS

In Minnesota, American Peat Technology^® (APT) harvests and manufactures reed-sedge peat products to be used in the agricultural and water remediation industries. Peat harvesting operations need a permit to mine from the MN Department of Natural Resources, which requires all disturbed areas be reclaimed. In 2016, APT began testing various reclamation techniques, including the use of live stakes, seed mixtures and donor soil to revegetate a final slope at their harvest area. Abnormal rainfall caused flooding of the site and the seed mix was washed off the slope. Live stake survival was estimated to be less than 5% after two growing seasons. No other treatments have been applied to the area and very little has grown on the site. Potential causes for the low stake survival and lack of vegetative growth include poor soil fertility, insufficient moisture or some form of chemical imbalance. The purpose of this work is to evaluate soil health and fertility in disturbed and undisturbed peatlands to determine potential causes for the lack of regrowth.

Peat soils were collected along three transects within a grid on the previously harvested unvegetated slope. Grab samples were also collected from a vegetated and non-vegetated area that was previously disturbed about 15 years ago, and an area of undisturbed peatland. All samples were analyzed for pH, % organic matter, moisture content, cation exchange capacity, trace and major elemental concentrations, and nutrient availability to plants.

Organic matter and pH in all samples ranged from 71.9% to 90.8% and 5.0 to 6.5, respectively. Plant-available nitrogen concentrations were highest in the near-surface samples collected in the vegetated disturbed area (23.5 to 27.8 ppm) compared to the non-vegetated disturbed area (7.3 to 14.9 ppm) and ranged from 8.1 to 37.2 ppm for the slope (highest concentration on the upper slope transect) and 0.3 to 1.2 ppm for the natural peatland. For plant-available concentrations of phosphorous and potassium, the range across all samples was 2 to 6 ppm and 6 to 30 ppm, respectively, with no discernable trends. Cation exchange capacity ranged 8.4 to 21.8 meq/100g across all samples.