Nutritional (Fe, Mn, Ni, and Cr) and growth responses of rice plant affected by perennial application of two bio-solids.

Trace toxic elements often restrict the land application of different bio-solids in agriculture. In order to evaluate the separate influence of the municipal solid waste compost (MSW), sewage sludge (SS) and combined application with inorganic fertilizers (chemical fertilizer (CF)) on nutritional (Fe, Mn, Ni, and Cr) and growth responses of rice plant, a research was conducted on paddy soil from 2013 to 2015. Obtained results showed that SS levels were superior to MSW in most studied traits. The maximum chlorophyll content (46.52), plant height (162.6 cm), biomass (23.33 t ha-1), soil available Fe (206.26 ppm), Ni concentration in the root (14.41 ppm) and shoots (3.16 ppm), Cr concentration in the root (12.43 ppm) and grain (3.65 ppm), and Mn concentration in grain (66.938 ppm) belonged to SS levels, specially enriched 40 t ha-1, when it was added to the soil for three continuous years. The highest 1000-grain weight (29.89 g), yield (6.86 t ha-1), harvest index (48.17%), and soil available Mn (712.7 ppm), Fe, and Ni concentration in grain (107.92 and 8.79 ppm, respectively) were recorded in 3 years of applying the enriched 40 t ha-1 MSW. Accumulation of Ni in grain in critical levels and negative effects of CF treatments on toxic element entry to soil and plant were two important findings of this research that need management.