U.S. Department of Agriculture (USDA) research published Friday confirms what farmers seem to have known for hundreds of years: that manure helps restore soils, even those highly damaged post-mining landscapes.
Soil scientist Paul White at the Agricultural Research Service (ARS) Sugarcane Research Unit in Houma, Lousiana, was part of a team that studied whether adding cow’s manure compost to soil at post-mining sites would provide the carbon needed to support a healthy plant cover.
The experts also wanted to determine if the compost could reduce levels of lead and zinc that could contaminate runoff during heavy rain.
Two years after they worked on improving the selected area with cows’ compost, White and his colleagues conclude animal poop is the best cure for mining-affected lands.
Specifically, they found that soils in the high-compost plots had significant increases in pH, plant-available phosphorus, total nitrogen, carbon, and available water.
Heavy use of compost also increased microbial biomass, enzyme activity and nitrification potential, all of which create and support favourable conditions for plant establishment and growth.
In this study, the researchers also found that high rates of compost lowered lead and zinc availability by about 90%, which they say can reduce the amount of lead and zinc that could run off and pollute nearby waterways.
The experts focused their remediation efforts in areas of the Tri-State Mining District of south-western Missouri, south-eastern Kansas, and in north-eastern Oklahoma. The district produced 50% of the zinc and 10% of the lead in USA from 1850 to 1950.
The last active mine closed in 1970, but mining’s ecological legacy remains throughout the region—lead-contaminated acidic soils, toxic smelter sites, large quantities of mine tailings called “chat,” and thousands of acres of land with little or no vegetation.
The solution, though a bit “messy,” is cheap and easily available, which are factors experts think will be more than welcome by the financially-hit mining industry.