Abstract: The effect of organic farming (using vermicompost, farmyard manure, poultry manure and cowdung) on the mineral (Fe, Zn, Ca, Mg, N, P and K) and nitrate contents of amaranthus, spinach and tomato, as well as soil quality, was investigated during kharif and rabi in Hyderabad, Andhra Pradesh, India. The conventional fertilizers were used as the control. The organic farming significantly increased the Fe, Zn, Ca, Mg and P contents in amaranthus, spinach and tomato crops as the soil that had been managed organically had more microorganisms, which produced many compounds that influence the plant to absorb more micronutrients from the soil. The conventionally grown amaranthus, spinach and tomato contained significantly higher nitrates compared to the organically grown crops.
Reference: Shankar, K.S., Sumathi, S., and Shankar, M. (2008). Minerals and microbiological quality of organically and conventionally grown vegetables. Indian Journal of Dryland Agricultural Research and Development 23(1): 87-95.