Cultivo de brócolis (Brassica oleraceae var. italica), em sucessão a adubos verdes, sob manejo orgânico

Abstract

The green manure has been adopted as an alternative to the cycling of the nutrients via organic residues of animal origin. This study had the aim to evaluate the treatments: corn (Zea mays) with jack bean (Canavalia ensiformis), corn with sunn hemp (Crotalaria juncea), and single corn crop, as a green manure to the broccoli culture, in succession conducted under organic cultivation. The work was conducted in two stages. The phase 1 consisted in the growing of the green manures. Field experiments were conducted in a randomized block, with five repetitions: T1: corn intercropped with jack bean; T2: corn intercropped with sunn hemp; T3: single corn crop (monoculture); T4: fallow. It was evaluated the influence of the intercropping in the productivity of the corn, as well as the production of biomass and the accumulation of the nutrients N, P and K in the produced biomass. In the phase 2 of the experiment, it was conducted the no-till planting of broccoli with the distance of 1 m x 0,5 m. To the broccoli, it was evaluated the fresh and dry weight, the diameter and circumference of the inflorescences. To the stalk, it was determined the fresh and dry weight and the length. In the leaves, it was determined the weight of the fresh and dry matter. The amount of N, P and K in all parts of the vegetable was quantified. In both phases, it were evaluated the influence of treatment in the biomass of the spontaneous plants, utilizing the magic square methodology. The treatment T1 showed the highest values of productivity of the green corn, followed by T2. The amount of N, P and K accumulated in the corn ear did not show significant difference among the treatments. The treatment T1 and T2 also showed high values in the production of the dried biomass and by consequence higher quantity of N and K in the straw. In phase 2, it was verified higher productivity, circumference and diameter of inflorescences of the broccoli to the treatments T1 and T2 in relation with the T4 (straw), as with the amount of N. In relation with the stalk, there was a significant difference only in fresh weight between the treatments T2 and T4. The green manure provided the control of spontaneous plants in both phases of the experiment, with treatment T1 and T2 establishing higher control of first phase and T3 and T4 in second phase. It was concluded that the practice of green manure increased the productivity of the broccoli, affected by corn intercropped with leguminous plants, which allowed the high contribution of organic matter and nutrients to the soil. It may also contribute to the generation of income by the farmers when they are not cultivating vegetables.