Besides physical productivity and soil conservation, in horticulture, protected cultivation and preparation of the soil require high investment, hard work and external inputs. The objective of this study therefore was to identify combinations of environment, soil preparation and planting season which would improve economic performance and yield in the organic farming of lettuce in Rio Branco, Acre. Growing the crop was carried out in four environments: 1 - 52% shading provided by a trellis with passion fruit; 2 - 35% shading in a greenhouse; 3 - 50% shading under a screen; 4 - in the sun with no shade (control). Each area was considered as a separate trial, in which three soil preparations (no-tillage, minimum tillage and conventional tillage) and two planting seasons (dry and rainy) were assessed in a randomized block design with four replications. The cost of production was taken to be the sum of all the values (inputs) and operations (services) used in the production process, including the respective alternative or opportunity costs, and any depreciation of the installation. Cultivation in a greenhouse or under a shading screen increases productivity in the dry season, while in the rainy season, productivity is higher for crops grown in a greenhouse. No-tillage and minimum-tillage cultivation in the sun, or minimum-tillage cultivation under screens, afford greater productivity that in the soil tillage. Supernormal profit (RMe > CTMe) is afforded by cultivation in the rainy season (summer), in the shade provided by a trellis of passion fruit, in the sun, by conventional tillage and no-tillage under a trellis, and by no-tillage in the sun.
