Nutrient accumulation in lettuce plants, cv. Babá, was quantified as a function of organic and mineral fertilisers, in a low fertility soil. The experiment was established by transplanting seedlings to 5 dm³ capacity pots in a greenhouse. The experiment was laid out in a complete randomised block design with three replications ordered in factorial arrangement (4 x 3) of four doses of organic compost (0, 0.9, 1.8 and 2.7 dm³; equivalent to 0, 33, 66, and 99 t/ha, in drought basis) and three mineral fertiliser levels (0, 1 and 2). Level two carried doses of macro and micronutrients normally recommended for the culture, with level one carrying half the dose of level two. The maximum estimated yields were 119.5, 119.4 and 153.9 g/plant with 37.7, 18.9 and 13 t/ha compost doses, for levels 0, 1 and 2, respectively. Organic compost doses resulted in a less intense increase in N foliar concentration, compared with mineral fertilizers, increased P, K, and Na concentrations and diminished Ca concentrations, revealing that organic fertilisers promote monovalent cations in high doses, prejudicing Ca absorption.
Lactuca sativa L; organic-mineral fertilizers; mineral nutrition
