Chemical characterization and challenges

The role urban and peri-urban agriculture (UPA) in reducing urban poverty and ensuring environmental sustainability were recognized by the Millennium Development Goals (MDGs). Soil, water and produce samples from four major UPA production systems especially from railway gardens (RG), balcony gardens (BG), terrace gardens (TG), farms (F) were collected and analyzed for nutrients, heavy metals, trace elements and contaminants. The use of wastewater among RG accounted for 98% overall irrigation water usage; 3 ppm cadmium (Cd) 5 ppb mercury (Hg) and high loads of faecal coliforms (MPN<1200) were also detected in majority of samples. Majority of the irrigation water samples falls under C1S1 category except one belongs to C3S1 indicating high salinity hazard. Piper trilinear diagram revealed two possible types of water including CaHCO3 (type 1) and Ca-Mg-Cl (type 3). Levels of copper (Cu), chromium (Cr), nickel (Ni), strontium (Sr), cobalt (Co) and boron (B) from the soils in various parts of MMR exceeded the recommended safety threshold standards and Maximum Allowable Concentration (MAC) by various countries.