Resumo

BESTEIRO, S.I.  e  DESCALZO, A.I.B.. Contenidos de nitrógeno y fósforo del suelo ante un cambio de cobertura y condición topográfica. RIA. Rev. investig. agropecu. [online]. 2021, vol.47, n.2, pp.285-292.  Epub 11-Ago-2021. ISSN 1669-2314.

The prairies of the Depression of the Salado River are characterized by a high proportion of soils with productive limitations related to water excess, salinity-sodicity and edaphic deficiencies of some nutrients. This is caused by the nature of the Salado River Basin which is immersed and due to the poverty of the original materials. Soil nitrogen and phosphorus are the deficient nutrients in these environments and, therefore, are conditioning factors of production. The objective of the work is to study the effects and/or consequences of the implantation of fast-growing commercial afforestation (Eucalyptus sp.) on the total nitrogen content and labile phosphorus of some soils characteristic of the Depression of the Salado River. To achieve this goal, the total N and P available were determined by the methods of MicroKjeldahl and Bray-Kurtz 1 on soils of three localities of the Depression of the Salado River, in the province of Buenos Aires (Chascomús, Dolores and Uribelarrea). The samples were extracted from the surface horizon of the soil (0-20cm) with three repetitions per condition, completing a total of 36 composite samples. The analytical values of total nitrogen and available phosphorus were subjected, firstly, to a variance analysis and to a comparison of means (Tukey). Subsequently, the site variable was incorporated as a random factor in a mixed model analysis. The results obtained reveal that the available phosphorus contents are affected significantly by the changes in soil cover (p-value <4.00e-06) and topographic condition (p-value <2.55e-06), so that the highest contents of this nutrient were found in situations of low and forest cover. On the other hand, the total nitrogen content responds only to a change in the coverage (p-value <1.01e-05), being higher its proportion under afforestation. It is concluded that the installation of fast-growing forest species generates significant changes in the availability of phosphorus and total nitrogen content in the soil. It has been recognized higher proportions of total nitrogen and phosphorus content available under the Eucalyptus afforestation compared to the herbaceous cover that they replace.

Palavras-chave : soil chemistry fertility; pasture-afforestation conversion; depression of the Salado River..

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