Effect of sewage sludge and cobalt treatments on tomato fruit yield, weight, and quality

Abstract

The effect of increased concentrations of cobalt (Co) (0,50,100, and 200 mg Kg^‐1) and treatment with sewage sludge was investigated on the yield and quality of tomato (Lycopersicon esculentum Mill cv. Ramy), grown in a calcareous soil. Anaerobically digested sewage sludge was applied at the rates of 2 and 4 g sewage sludge/100 g soil d.w., equivalent to 60 and 120 t ha^‐1. Treatments were compared with a control, which was not fertilized at all. A significant increase in fruit yield of the plants, grown in sewage sludge amended soils, was observed. Cobalt treatments did not affect tomato production, but fruit quality, such as electrical conductivity and fruit acidity, seemed to be affected. Fruits tended to become more acid.