Meena, M. C.; Patel, K. P.; Singh, D.; Dwivedi, B. S. Long-Term Effect of Sewage Sludge and Farmyard Manure on Grain Yields and Availability of Zinc and Iron under Pearlmillet (Pennisetum Glaucum)-Indian Mustard (Bassica Juncea) Cropping Sequence. Indian J Agri Sci 2008, 78 (12).