Effect of zinc enrichment of agricultural waste compost on yield and some ‎qualitative characteristics of lettuce in greenhouse cultivation (Lactuca sativa L.‎‏ (‏

Using organic agricultural wastes to produce vermicompost and compost is a sustainable way in order to reuse these wastes. In order to investigate the effects of different zinc-enriched vermicompost and compost on yield, quality, and nutrient content of lettuce, an experiment as factorial based on completely randomized design was carried out. The first factor was organic residues at three levels (carrot, sugar beet and date wastes), the second factor was zinc enrichment at three levels (zero, 1000, and 2000 mg / kg), and the third factor was mixing with weak soil at four levels of (zero, 2 , 4 and 6% by weight). Results showed that effect of organic residues enrichment on the growth and yield of lettuce plants was the positive and plants grown in vermicompost produced from carrot waste, had better results than those, which grown in vermicompost produced from beet or date waste. Carrot wastes had the highest amount of microelements (Fe, Mn, Zn, Cu) among the three wastes used, and enriched with 2000 mg/kg zinc had the highest amount of these microelements. The highest amount of phosphorus (0.82%) and leaf area (157 cm2) were obtained in carrot wastes enriched with 2000 mg / kg. Among different levels of organic residues, 4 and 6% had the greatest effect on lettuce growth and yield. Overall, enrichment of organic residues with minerals can meet the nutritional needs of lettuce grown under greenhouse conditions.