Utilization of Bagasses Sewage Sludge Based Compost as a Peat Substitution for Lettuce Cultivation.

In this study, the use of bagasses sewage sludge based compost (BSC) as a substitution for widely using peat in growth media for a horticultural　crop, lettuce (Lactuca sativa L.), was evaluated. Five treatments were established, based on the addition　of increasing quantities of BSC to peat (0%, 10%, 25%, 40%, 60% v/v). Physical and chemical　analyses of the different growth media were undertaken. Plant growth, biomass production and macronutrient (N, P, K, Ca, Mg), micronutrient (Fe, Cu, Mn, Zn) and heavy metal (Pb, Ni, Cd, Cr) contents of plants were determined. In general, the proposed growing media with peat and BSC had adequate physical and physico-chemical properties and notable contents of plant nutrients, mainly P, K, Ca and Mg. Moreover, addition of BSC to peat increased the nutrient content in lettuce plants compared to plants grown in peat only substrate. The use of BSC did not affect the germination rate, even at 60% compost. Highest growth and yield parameters were obtained from the plants grown in the medium prepared by mixing the peat with 40% of BSC. In addition, the mixture with the most　BSC (60%) gave the greatest contents of macro and micronutrients. The concentration of trace elements in plant tissues obtained from proposed growing media with BSC and peat were far lower than the ranges considered phototoxic for plants. Utilization of BSC can be considered as an alternative media component to substitute the widely using expensive peat in horticulture.