Impact of urbanization on soil loss: a case study from sod production

The rapidly increasing population of urban centers leads to the increasing need for greenspaces. Sodding of turfgrass provides instant greenspace, but it removes soil from sod farms. The extent of such removal has not been widely quantified. The amount quantity of soil and organic matter lost with sod harvest and the associated cost of nutrients lost from six sod farms in the Marmara region of Turkey were determined. Soil loss ranged from 166 to 243 Mg ha^-1 year^-1, while the associated organic matter loss ranged from 1 to 6 Mg ha^-1 year^-1. The amount of soil loss increased with increases in gravimetric water, clay, and silt contents, and duration under sod harvest, while it decreased with an increase in sand content. Annual nutrient lost ranged from 117 to 449 kg ha^-1 for N, from 2 to 18 kg ha^-1 for P₂O₅, and from 21 to 175 kg ha^-1 for K₂O. Replacing the nutrient lost would cost about $134 ha^-1 year^-1 for sandy soils and $444 ha^-1 year^-1 for fine-textured soils. Soil lost with sod harvest was 134 times higher than that from agricultural lands by erosion in the region, although the area under sod production is much smaller than that under croplands. Similarly, organic matter loss was 4 to 5 times higher than the accumulation rate under established turfgrass in golf courses and lawns in locations with similar climate. Overall, sod harvesting results in significant and costly soil, organic matter, and nutrient loss, which, although small in area, can be an important component of total soil erosion.