High-Carbon Amendment Impacts on Reclaimed Mined Land Nutrient Cycling and Wheat Growth Under Greenhouse Conditions.

Reclaimed mined soils are often low in most nutrients and organic matter even when mixed with the original topsoil. The goal of this greenhouse study is to evaluate the impacts of carbon (C) amendment type (biochar, mulch, biochar-mulch mix) and rate (1% and 2% C addition) on winter wheat growth and soil nutrient cycling in fertilized and nonfertilized mined soils. A silty clay loam soil with 1.6% organic matter, pH 5, and limited nutrient content was collected from a newly reclaimed coal mine site near Jasper, IN. The soil treatment combinations were prepared in pots containing 1800g dry-weight soil/amendment mixture using three replications in a randomized complete block design. Winter wheat (Pioneer 25R40) was seeded at 5 cm depth and both shoots and roots were collected at 4 harvest dates (45, 75, 105 and 135 days post-planting). Soil water content was maintained between 55%-80% available water throughout the experiment. Carbon amendment type showed a significant effect on soil aggregate stability, soil soluble inorganic and organic carbon, soil nitrate concentration and Mehlich 3 extractable phosphorus and potassium. Carbon amendment rate significantly impacted soil aggregate stability and Mehlich 3 extractable potassium. Plant biomass production was primarily affected by the fertilizer addition. Soil and wheat nutrient cycling was affected by time, as well as time and treatment interactions. The results from this greenhouse study will augment ongoing field studies to provide carbon amendment guidelines to improve mined land soil quality and health.