Adubação e dinâmica de plantas daninhas em sistema de plantio direto orgânico de milho

• Autor(a) principal: Fontanetti, Anastácia
• Data de Publicação: 2007
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1090
• topic: Milho orgânico; Plantio direto; Ervas daninhas; Organic corn; No-tillage system; Weeds; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOTECNIA

The objective of this work was to evaluate and compare weed population establishment, foliar nutrient contents and corn production under conventional and organic no-tillage systems. The experiment was conducted in 2004/2005 and 2005/2006 at the Experimental Station of Coimbra, MG, owned by Universidade Federal de Viçosa, UFV. The treatments were constituted by the following no-tillage systems, defined as: conventional 1 (C1NTS): without fertilization + herbicides; conventional 2 (C2NTS): with mineral fertilization at the dose of 150 kg ha-1 of the formulate 8-28-16 + 50 kg ha-1 of urea on cover crop + herbicides; conventional 3 (C3NTS): with mineral fertilization at the dose of 300 kg ha-1 of the formulate 8-28+16 + 100 kg ha-1 of urea on cover crop + herbicides and organic no-tillage system (ONTS): soil fertilized with organic compound at 40 m³ ha-1 applied as cover crop along the seeding line, after corn emergence and weed cutting. The cover crop plant used was black oat (Avena strigosa Schreb) at a density of 80 kg ha-1 seeds. The results obtained allowed to conclude that the difference in weed population establishment between the conventional and organic no-tillage systems is related to the method (chemical or mechanical) used to control weeds rather than to the fertilization source (organic or mineral). The use mechanical control (cutting) under the organic no-tillage system favors weeds propagated vegetatively such as Cyperus rotundus, Artemisia verlotorum, Commelina benghalensis and Cynodon dactylon, and weeds presenting high re-growth capacity such as Bidens pilosa, making it difficult to manage these plants under ONTS. After three years of implantation of the organic no-tillage system, a sharp corn production decrease was observed, mainly due to weed competition with corn and possibly to nutritional nitrogen deficiency due to black oat and corn succession.