Rooftop Farm Soils for Sustainable Water and Nitrogen Management

Urban Farm DB summary

This study compared various soil mixes for rooftop farms to assess stormwater retention, yield, and quality of drought-sensitive crops. A 5-week greenhouse experiment cultivated leaf lettuce using an irrigation rate mimicking average growing season precipitation for New York City, comparing five soil mixes made of coconut coir, biochar, and animal manure compost, plus a commercial rooftop farm soil. Three soil mixes showed good yield with water retention rates up to 100%, and drainage nitrogen output levels were less than 13% of current levels at an operational rooftop farm in NYC.