English abstract
Kala Compost is a mixture of treated sewage bio-solids and green wastes. It can improve soil fertility and plant growth. However, long-term application of treated sewage bio-solids could result in heavy metals accumulation and some health problems. The objective of this study was to evaluate the effect of a long run application of Kala compost mixed with chemical fertilizer on soil and plant productivity. Soil and plant (mainly cucumber) samples were taken from 12 greenhouses that received Kala compost continuously for the last five years. No symptoms of physical or chemical problems were observed in the greenhouses and measured soil samples. Moreover, the soil had sufficient values of different nutrients for plant growth and all measured micronutrients (heavy metals) were within the safe limit and below the range of the international standards. An excellent growth was observed in all grown plants and no symptoms of elements deficiency were found. Chemical analysis of fruit samples did not show any accumulation of heavy metals and all measured elements were within the safe limit and did not exceed the international standards. It can be concluded that Kala compost was a good media for plant growth that can enrich the soil with different elements needed for higher yield. However, more monitoring is needed with treated bio-solid application but good management could be the key to avoid any adverse effect of any contaminant.
