The Potential of the Application of Olive Cake and Stone Cutting Waste for Soil Amendment

The recycling of waste is considered an attractive solution for the high amounts of waste generated worldwide. Some waste including olive waste and stone cutting waste present considerable environmental challenges for environmental planners and local communities. Due to their impacts on the environment and human health, this paper investigates the recycling of olive cake (OC) and stone cutting sludge (SCS) and their use for soil amendment. It evaluates their effect on soil pH, soil permeability, and maize growth. Thirteen different treatments containing clay soil (CS), OC, and SCS with different proportions to be used as maize seed growing media. The media were placed in pots and each treatment had three replicates with a randomized complete block design and was irrigated with fresh water. OC had high permeability, low pH, while SCS had low permeability and alkaline ph. The growing media which contained CS and SCS at 70:30 (w/w) ratio (T8) exhibited an increase in the number of leaves (8.7 %), plant height (5.5 %), stem diameter (34.3 %), shoot fresh weight (18.2 %), shoot dry weight (23.5 %), fresh root weight (4.29 %), dry root weight (38.10 %), leaf length (31.9 %), and leaf width (4.86%), while OC application resulted in significant reductions in all the above-mentioned parameters. In the treatments containing the three mixtures (CS, OC, and SCS), stone cutting sludge countered the negative effects of OC and enhanced the performance of the mixed soil, resulting in significant improvements of the growth indicators. The obtained results highlighted the potential of using waste as a soil amendment technique instead of the disposal of waste. This could decrease the destructive impact of waste on the environment and reduce the costs of transportation and disposal.