BIOSOLID COMPOSTS EARN HIGH MARKS
Research continues to support the idea that there is a market for biosolids. Researchers at Delaware Valley College studied the addition of municipal solid waste biosolid compost to soil prior to seeding and sodding Kentucky bluegrass. In order to simulate typical conditions at new construction sites, they stripped off the topsoil from the research plots using a bulldozer. They then tilled the soil 4 to 6 inches deep and applied varying levels of compost. The treatments were no amendment, fertilizer only (three rates) and 1, 2 or 3 inches of compost. The compost was 60 days old and initially had high rates of soluble salts and ammonium nitrate. The plots were then seeded or sodded with ‘Touchdown’ Kentucky bluegrass and evaluated over the next two years for color, density and weed population.
The seeded plots with compost-amended soil had a slow start, but then had exceptional results. Although the fertilized plots germinated and established quicker, over the long run, compost-amended plots were more dense than the control or fertilized plots. In addition, turfgrass color ratings were higher in compost-amended plots for nearly all dates data was collected. The exception came during the summer after the fall seeding. Drought conditions caused the Kentucky bluegrass to become stressed, especially the 3-inch compost treatment. However, the 3-inch compost did recover nicely with high color ratings through the remainder of the study. Fertilizer plots performed well in color ratings only at the beginning of the study. As for weed population, the control plots had the greatest percent weed cover and compost amended plots had very little weed population.
Amending with compost did not have the same impact for sodded plots. This same study found the sod established quicker with fertilizer only, but after a time, all treatments were nearly the same.
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