The effects of sewage sludge and nitrogen applications on grain sorghum grown [Sorghum vulgare L.] in Van-Turkey

The research was conducted in Van, located in the eastern Anatolia region of Turkey. The purpose of this research was to assess environmental hazards to crops and soils from sludge-borne heavy metal; and the potential of using sludge as an alternative to commercial fertilizer, yield, N content and uptake of grain sorghum (Sorghum vulgare L. A-298). Sorghum plants were grown on sandy clay soils under irrigated conditions. Three levels of biosolids were topically applied at rates of 7, 14 and 21 Mg ha⁻¹; and two level of nitrogen were also applied at rates of 40 and 80 kg ha⁻¹. The experimental design was a randomized complete block with four replications. Biosolids increased yields of dry matter and grain, plant length, N content of leaves, total N uptake and harvest index (HI). Grain yield was significantly correlated with plant length, N content of leaf and wholeplant, and total nitrogen uptake. Nitrogen harvest index (NHI) did not show significant correlation with any considered parameter other than harvest index. In contrast, nitrogen use efficiency (NUE) had a negative relationship with dry matter (DM) yield, N content of whole-plant, N content of grain and total N uptake. Diethylenetriamine pentaacetic acid (DTPA) extractable Cd, Pb and especially soil Zn concentrations increased with sewage sludge rates. In general, none of the heavy metals studied in both leaves and seed of crop reached either phytotoxic or toxic levels for humans or livestock [1]. The results showed that sewage sludge could be used as N fertilizer in grain sorghum production.