Resumo

LEDESMA, R et al. Efecto del rolado de baja intensidad (RBI) sobre la distribución radical de pastos y arbustos en un bosque del Chaco occidental. RIA. Rev. investig. agropecu. [online]. 2018, vol.44, n.2, pp.121-128. ISSN 1669-2314.

Woody plant encroachment and the reduction of grass density is a common process in Chaco region. Low intensity rolling chopping (RBI) is used to increase grass standing crop, reduce the density and volume of woody species, maintaining the tree structure. The objectives of this work were a) to evaluate the effect of RBI plus seeding of Megathirsus maximus cv Gatton panic on the root distribution of grasses and shrub species, in a “highland” site with forest and b) to examine the existence of niche separation by root exploration mechanism, it means high grass roots density in the top soil, versus high shrubs roots density in the subsoil. The study was conducted at the Experimental Station INTA Santiago del Estero, Argentina. Root density up to 1 m depth was assessed in three pits by treatment and differentiated by size and functional group, in four categories of soil depth. An analysis of variance was performed and root density means were compared using Duncan test. Most grass roots were located to 50 cm approximately, while the roots of shrubs were found along the entire soil profile. This evidence indicates that niche separation by root exploration mechanism not occurs. RBI increased grass roots density, mainly of M. maximus, at the soil upper layer. Its mean root density decreased with increasing depth. In RBI treatment, there are more M. maximus plants than in control. RBI increased the grasses fine roots density. Mean density of shrub roots was greater in the control than in the roller chopping. RBI improved the physical conditions of the soil, allowing a greater root density of M. maximus, and exerting a competitive effect over shrubs.

Palavras-chave : Grasses; Rolling chopping; Roots; Semiarid Chaco; Shrubs.

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