Residual effect of organic compost on lettuce growth and yield

This paper aimed to evaluate the residual effect of organic compost fertili zation on lettuce growth and yield. Seedlings of 'Baba' lettuce were fertil ized with five doses of organic compost (0.0, 22.8, 45.6, 68.4 and 91.2 ton /ha of dry matter), in the presence and in the absence of mineral fertilize r (643 kg/ha of 4-14-8 plus two side dressings of 30 kg/ha of N). The resid ual effect was evaluated by carrying out a second cultivation on the same p lots with no fertilizer addition after the first cultivation. Fertilization with organic compost increased the second cultivation yield up to 27,367 k g/ha of fresh weight at the highest dose, in plants grown between 80 and 11 0 days after organic compost application. The mineral fertilization showed no residual effect. The residual effect also resulted in increases in soil exchangeable bases, P, and effective soil cation exchange capacity (CEC) re aching values of 10.77 cmol(c)/dm(3), 461 mg/dm(3) and 11.08 cmol(c)/dml(3) , respectively.