Phytotoxicity of composts obtained by accelerated composting on crops cultivated in Doukkala region,Morocco [Phytotoxicité de composts obtenus par compostage accéléré sur des plantes cultivées dans la région des Doukkala,Maroc]

In this work,an innovative accelerated composting system using bioreactor was designed to develop four composts derived from sewage sludge and agricultural by-products (straw,collars and sugar beet leaves). phytotoxicity of leachates derived from l2,l3,l4 and l5 composts was evaluated using six crops cultivated in the doukkala region (alfalfa,bersim,cress,wheat,corn and tomato). our results showed that the six studied species were not equally affected by the phytotoxicity of tested leachates. the impact on germination and root growth relied on both the compost used and the crop species. the germination rate showed no significant differences in alfalfa and bersim for four leachates while a more pronounced phytotoxic effect was observed in corn and tomato. unlike immature composts l2 and l4,the results showed that composts l3 and l5 were stable and did not exhibit any phytotoxic effect and even a stimulatory effect of germination and root growth was observed. this was demonstrated under greenhouse conditions where the effect of compost 3 on the rate of emergence and growth in cress,wheat and sugar beet was studied. the results showed that the compost has no significant depressive effect on the emergence when compared to the control. furthermore,the addition of compost at different doses (5,10 and 20 t / ha) stimulates the growth of common wheat and sugar beet. however,in cress stimulation of growth occurred at lower concentrations. ultimately,a moderate intake of compost at 5 t / ha seems to be adequate for the three crops.