Resumo

DELGADO H., Hernando; NAVAS R., Gloria Elena; SALAMANCA S., Carmen Rosa  e  CHACON D., Adolfo. Legume improved fallows: a promissory agroecological alternative for allelopathic weed control in rice and maize crops in the Colombian Eastern Plains. Agron. colomb. [online]. 2009, vol.27, n.2, pp.227-235. ISSN 0120-9965.

Chemical weed control in rice reaches up to 20% of total crop costs, therefore reducing profitability. Seeking for management alternatives, the present research assessed the effect of three plowing and four legume improved fallow systems, a native fallow and three herbicide doses on resurging crop weeds, rice and maize yield and some soil properties. The experiment was carried out at Research Center 'La Libertad', in the city of Villavicencio, and in two farms in the Ariari river region, by means of a sub-split plot design with four repetitions. The strongest allelopathic effects were exhibited by Mucuna deeringianum (Bort.) Smal, with additional to herbicide weed control percentages ranging from 41 to 62%; followed by Crotalaria ochroleuca G. Don (20 to 46%). In the Ariari research site, such performance allowed obtaining higher (although not significant) maize and favored upland rice yields than those reached with full herbicide commercial doses; while reducing the latter by 30%, and still attaining adequate weed control. Both cover crops increased rice yield up to 1,446 kg ha^-1, while only C. ochroleuca increased maize yield in 331 kg ha^-1. The multiple and integrated agronomic benefits of fallow improvement periods highlight their potential for allelopathic weed control, and as an agro ecological practice in rice and maize crops.

Palavras-chave : legume cover crops; annual crops; weed integrated management.

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