Organic Cultivation of Tomato in India with Recycled Slaughterhouse Wastes: Evaluation of Fertilizer and Fruit Safety

Environmental and health safety of recycled slaughterhouse wastes-derived fertilizer and the produce obtained through its application is not well understood. Waste bovine blood and rumen digesta were mixed, cooked and sun-dried to obtain bovine-blood-and-rumen-digesta-mixture (BBRDM, NPK 30.36:1:5.75). 1.26 ± 0.18 log CFU mL−1 fecal coliforms were recovered in BBRDM. E. coli O157:H7, Mycobacteria, Clostridium sp., Salmonella sp., Bacillus sp. and Brucella sp. were absent. No re-growth of pathogens was observed after 60 days storage in sealed bags and in the open. However, prions and viruses were not evaluated. Heavy metals (Pb, Cr, Cd, Cu, Zn, As, Ni, Mn) concentrations in BBRDM were within internationally permissible limits. BBRDM was applied for field cultivation of tomato during 2012–2013 and 2013–2014. Lycopene and nitrate contents of BBRDM-grown tomatoes were higher than Diammonium phosphate (DAP) + potash-grown tomatoes because BBRDM supplied 2.5 times more the amount of nitrogen than DAP (NPK 18:46:0) + potash (NPK 0:0:44). Heavy metals and nitrate/nitrite concentrations in tomatoes were within internationally acceptable limits. BBRDM-grown tomatoes showed no mutagenic activity in the Ames test. Sub-acute toxicity tests on Wistar rats fed with BBRDM-grown tomatoes did not show adverse clinical picture. Thus, no immediate environmental or health risks associated with BBRDM and the tomatoes produced were identified