Beta-Glucosidase and Soil Organic Carbon in Urban Conservation Agriculture.

The potentials of using urban areas to grow food has recently been receiving quite an attention. Identifying agriculture systems that store carbon and enhance carbon cycling in these areas are important to maintain and improve urban soil quality. Soil enzyme beta-glucosidase and soil organic carbon, indicators of carbon cycling and soil health, were assessed in urban soils under different managements after 2 and 5 years of converting a turf grass lawn into an urban agriculture garden. A turf lawn at NCA&T was converted into an urban raised plot experiment during fall 2011. Raised plots of 3’by 6’ were established using anthropogenic soils and treatments till, no-till, conservation agriculture winter (CA winter) and conservation agriculture summer (CA summer) were randomly assigned and replicated four times. Tillage follows the conventional turning over of soil and the removal of crop residues after vegetable production season; no-till was like tillage treatment but without disturbing the soil apart from boring holes enough for planting; CA winter was planted with clovers during winter while CA summer was planted with sumhemp (Crotolaria juncea) during summer and with vegetables in all other times. Soils were sampled at the 0-10 cm depth in 2013 and 2016 and tested for soil beta-glucosidase and percent soil organic carbon. Both CA systems were significantly higher in beta-glucosidase enzyme activity than tillage in 2016 but only CA winter was not different to tillage in 2013. Soil carbon were the same after 2 years but after 5 years CA summer and CA winter were significantly higher than both tillage and no-till. The results indicate that systems that practices no-till with high residue cover crops such as conservation agriculture system may promote carbon cycling and carbon build-up in urban agriculture.