Lentil species, L. orientalis, is thought to be the progenitor of cultivated lentils and is presently designated as L. culinaris subspecies Oriental. Lentils are hypogeal, which means that the cotyledons of the germinating seed remain in the soil, and the plant is a diploid, annual, bushy herb with upright, semi-erect, or spreading, compact growth that typically ranges in height from 30 to 50 cm (12 to 20 in). The experiment was carried out to investigate the influence of Spent Mushroom Compost on lentil plant height, number of leaves, and dry matter accumulation. Various levels of spent mushroom compost and farmyard manure were used in the treatments. The results indicated that plant height rose with crop age, with the highest height seen in treatment T4. The number of leaves per plant was maximum with the T4 treatment. The treatment T4 accumulated the most dry matter. The T5 treatment had the maximum lentil grain yield. Overall, the findings indicate that SMC and FYM can have a considerable impact on lentil plant development and yield.