Assessing and Managing Soil Quality for Urban Agriculture in a Degraded Vacant Lot Soil.

An abundance of vacant land exists in the formerly industrial cities of the north central U.S., which have seen tremendous declines in their populations over the past 50 years. Many cities plan to utilize this land for functional greenspace and urban agriculture (UA) to improve the overall quality of life. This project is focused on an experimental site located in a series of adjacent vacant urban lots in Youngstown, OH where houses were recently demolished and removed.  The demolition process often leaves soils severely degraded and this experiment documents the soil’s initial condition following demolition, as well as the potential for improving soil conditions for UA by applying amendments produced from urban green wastes. The following treatments are being tested: 1) unamended control, 2) leaf compost, 3) leaf compost + intensive cover cropping, 4) leaf compost + hardwood biochar.  All plots are split plots comparing in ground cultivation with cultivation in 20 cm raised beds. Initially, soil compaction was identified as a primary constraint at the site with bulk density values of 1.79 g cm^-3  for in ground plots and 1.55 g cm^-3  for raised beds. The experiment was run for the 2011 and 2012 growing seasons and data have been collected on vegetable crop yield and on soil physical, chemical and biological properties and analyzed through both hypothesis testing and soil quality indexing.  Crop yield data from 2011 demonstrate strong treatment effects on both crop yield (p=0.001) and harvest index (p=0.005). Vegetable crop production averaged 2.4 kg m² in both compost and compost + biochar amended plots and 1.1 kg m²  in control plots.  Significant treatment effects have also been observed for a number of soil properties including: microbial biomass C, penetration resistance, and bulk density following 1 year of management. These results support the hypothesis that low-cost amendments produced from local green wastes can be used to improve degraded urban soils for specialty crop production and enhanced ecosystem services.