With the aim of evaluating the effect of earthworm casting (Chibui bari Righi & Guerra, 1985) in the production of lettuce seedlings (Lactuca sativa L.) cv. Simpson, two experiments ware carried out in greenhouse in the Federal University of the Acre, both in a completely randomized outline with six treatments and six repetitions, totalizing 36 experimental units, represented by 180 cm³ plastic cups. The treatments were defined from the mixture of six concentrations (0, 20, 40, 60, 80 and 100%) of soil and earthworm casting. Two soil types were used, eutrophic in the experiment 1, and dystrophic in experiment 2. At 34 days after the sowing the dry mass of shoot, root and total plant were evaluated. The results of experiment 1 indicate that the addition the earthworm casting in eutrophic soil promotes increase of dry mass of the aerial and total fast of the plant concentrations of earthworm casting 17.88% and 13.49%, respectively. However, the results of experiment 2 indicate that the addition of the earthworm casting to the dystrophic soil, responds to a cubic function, with maximum dry mass total and of root increase with concentrations of earthworm casting of 17.49% and 21.40%, respectively, with decrease in 68.23% and 67.48%, and increase maximum again with 100% of earthworm casting for both characteristics. The use of substrate prepared with soil and earthworm casting only contributes to the growth of lettuce seedlings if the chemical condition of the casting is more appropriate than the one of the soil in assisting the nutritious needs of the plants.
Lactuca sativa; organic fertilizer; Chibui bari
