Impact of organic soil amendments on phytochemicals and microbial quality of rocket leaves ( Eruca sativa ).

The effect of soil amendments prepared from organic wastes (sewage sludge and urban solid waste) at two concentrations (45 t ha(-1) as D1 and 135 t ha(-1) as D2) was evaluated on phytochemicals and microbial quality of rocket, a highly valuable vegetable. The addition of sewage sludge to the soil increased rocket yield 5.5 times compared to control and urban solid waste. Organic amendments increased the water content and the maturity stage of the leaves, which contributed to a reduction in the content of total and individual glucosinolates as well as flavonols and anthocyanins. However, higher content of vitamin C was observed after cultivation with sewage sludge at D2 compared to control leaves (204.6 and 177.4 mg 100 g(-1) of fw, respectively). This study shows that sewage sludge at optimum doses can be considered a suitable amendment because of increased crop yield without detrimental effects on phytochemicals, including vitamin C content, when the leaves reached the commercial maturity stage.