Changes in growth, yield and nutrient status of nine vegetables grown onto a soil substrate with two-phase olive mill waste sludge addition

Abstract

The present experimental work was carried out in order to evaluate changes in growth, yield and nutrient status of nine vegetables grown on soil substrates with four doses (0%, 2.5%, 5% and 10% v/v) of a two-phase olive mill waste (OMW) sludge as an alternative strategy of their handling. Growth results showed that under 2.5% OMW, zucchini and cucumber mini plants tended to increase their total plant fresh weight (FW) whereas cucumber long and large-sized tomato presented the opposite trend. Under 5% OMW, watermelon, cucumber mini and zucchini presented the lowest total plant FW change whereas pepper and large-sized tomato the greatest decrease. Under 10% OMW addition, large-sized tomato and pepper, followed by watermelon, showed the greatest total plant FW decrease whereas all plum tomato plants under 10% OMW died at the end of the experiment. Yield results showed that among the vegetables tested, melon followed by large-sized tomato, plum tomato and cucumber long presented higher yield increase, eggplant the lowest one whereas watermelon produced no fruits. Based on the fact that yield gathers the greatest commercial interest for vegetable cultivation, we could assume that the addition of either 2.5% OMW for the majority of vegetable tested (except eggplant and watermelon) or 5% for melon, plum tomato, large-sized tomato and cucumber long could provide a sustainable alternative methodology for OMW management. Regarding plant nutrient status, the majority of the nutrient element concentrations determined revealed their non-significant change.