EVALUATING THE PERFORMANCE OF Lactuca sativa UNDER FOUR DIFFERENT ORGANIC FERTILIZERS AND SUBSEQUENT IMPACT ON THE SOIL HEALTH

To test the effects of organic fertilizers (OF) supplementation on the crop yield, soil characteristics and agro-physiological traits of lettuce plants in field conditions, an experiment was carried out using four OF: horse manure-green waste (OF1), poultry manure-green waste (OF2), olive pomace-green waste (OF3) and phosphate sludge-green waste (OF4) applied on lettuce plants. Results revealed that OF4 was the most effective increasing lettuce yield by 104% compared to the control. Plant nitrogen and phosphorus were significantly enhanced in OF-plants. As for physiological traits, leaf area index, stomatal conductance and chlorophyll fluorescence were improved by OF4, while chlorophyll a, b, total chlorophyll and carotenoid concentration were significantly enhanced under OF1-plants. Total soluble sugars and proteins concentration were enhanced in all OF-plants and the highest increases were registered in lettuce plants under OF1 and OF2 by 112 and 91% and 85 and 92%, respectively. In addition, soil total organic carbon and nitrogen were significantly improved by OF3, while soil phosphorus and total glomalin was enhanced by OF4. These findings highlighted the OF ability to improve lettuce productivity and its soil quality under field conditions, especially with OF4 treatment which was the most effective to promote lettuce productivity and soil fertility.