Resumen

RENZI, J.P; VANZOLINI, J.I; AGAMENNONI, R  y  CANTAMUTTO, M. Efecto de rotaciones agrícolas con cebolla sobre las propiedades químicas del suelo y producción de policultivo avena-vicia y resiembra natural de Viciavillosa Roth. en el sur de Buenos Aires. RIA. Rev. investig. agropecu. [online]. 2017, vol.43, n.3, pp.247-255. ISSN 1669-2314.

In the river Colorado valley (VBRC) in southern Buenos Aires, hairy vetch fits as a cover crop (CC) for its high biomass production in late spring. Onion sowing on vetch CC it is becoming increasingly important in the VBRC. However, for this management might be possible it is important to accumulated high vetch biomass before onion sowing. The objective of this study was to evaluate the productivity of hairy vetch-oat mixture under different predecessor crops and the possibility of using the natural reseeding of vetch as a cover crop autumn in the next cycle. The experiment was established in the EEA INTA H. Ascasubi. The crops predecessor before vetch-oat mixture, were different sequences of onion, alfalfa, ryegrass, foxtail millet, wheat and sunflower. Soil fertility and productivity of mixture were evaluated during the first cycle and natural reseeding of vetch in the second. Relative biomass production of vetch and oats was influenced by the effect of the predecessor, not its total production. Alfalfa forage predecessors reduce participation of vetch in the mixture; this might be due to the low phosphorus / organic matter ratio left in the soil. The number of seeds of hairy vetch established by reseeding and left in the soil seed bank after 8 months, was 36.8 ± 9.8 and 25.6 ± 10.2% of the total spread. A dispersal ≥80 seed m^-2 (≈ 2.9 g m^-2) might be enough to establish for reseeding a hairy vetch crop with a density of 30 plants m^-2, suitable for good production biomass in spring. Increases in the number of hairy vetch seeds spread increased the biomass production in late autumn. The early establishment of hairy vetch by reseeding might be increase the growth over warm temperatures of late summer and autumn, and improve the biomass accumulation and contribution of N. In VBRC is possible to get biomass production potential of hairy vetch, established by reseeding of 4.9 t ha^-1 in July, which incorporated 176 kg N ha^-1 into system.

Palabras clave : Rotations; Onion; Cover crop; Seed production.

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