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RESEARCH ARTICLE

Soil chemical management drives structural degradation of Oxisols under a no-till cropping system

Márcio R. Nunes A H , Alvaro P. da Silva G , José E. Denardin B , Neyde F. B. Giarola C , Carlos M. P. Vaz D , Harold M. van Es E and Anderson R. da Silva F
+ Author Affiliations
- Author Affiliations

A University of São Paulo/Luiz de Queiroz College of Agriculture, Department of Soil Science, Pádua Dias, 11, CEP 13418-900 – Piracicaba, São Paulo, Brazil.

B Embrapa Trigo, Rodovia BR 285, km 294, CEP 99001-970 – Passo Fundo, Rio Grande do Sul, Brazil.

C State University of Ponta Grossa, Department of Soil Science and Agricultural Engineering, Gal. Carlos Cavalcanti, CEP 84030-900 – Ponta Grossa, Paraná, Brazil.

D Embrapa Agricultural Instrumentation, CEP 13560-970 – São Carlos, São Paulo, Brazil.

E Cornell University, School of Integrative Plant Science, Soil and Crop Sciences Section, Ithaca, NY 14853–1901, USA.

F Federal Institute Goiano, Department of Agronomy, Urutai, Goiás, Brazil.

G Deceased. Formerly of University of São Paulo/Luiz de Queiroz College of Agriculture, Department of Soil Science, Pádua Dias, 11, CEP 13418-900 – Piracicaba, São Paulo, Brazil.

H Corresponding author. Email: marcio_r_nunes@usp.com; marcio_r_yahoo.com.br

Soil Research 55(8) 819-831 https://doi.org/10.1071/SR17063
Submitted: 22 February 2017  Accepted: 2 June 2017   Published: 28 June 2017

Abstract

Physical degradation of the subsurface layer of soils reduces the effectiveness of no-till (NT) as a sustainable soil management approach in crop production. Chemical factors may reduce the structural stability of Oxisols and thereby exacerbate compaction from machinery traffic. We studied the relationship between chemical management and structural degradation in Oxisols cultivated under NT at three sites in southern Brazil. The surface and subsurface layers of the soils were characterised chemically and mineralogically and three physical attributes related to soil structural stability (readily dispersible clay in water, mechanically dispersible clay in water, and water percolation) were quantified for each layer. The same characterisations were performed on Oxisols collected from adjacent non-cultivated areas, to provide reference data for non-degraded soil. The levels of dispersed clay in the cultivated soil from the surface layer matched those of the non-cultivated soil, but for the subsurface layer higher dispersed clay levels in the cultivated soil showed that it was physically degraded relative to the non-cultivated soil. Water percolation was found to be slower through the Oxisols cultivated under NT, irrespective of the soil layer. The relationships between the three indicators of soil structural stability and the measured chemical and mineralogical variables of the soils were explored through an analysis of canonical correlation. The principal variables associated with the lower stability of the cultivated vs non-cultivated Oxisols were the lower concentrations of organic carbon and exchangeable aluminium and, for the surface layer, the higher pH. It is argued that structural degradation of Oxisols cultivated under NT, observed predominantly in the subsurface layer, has been aggravated by the accumulation of amendments and fertilisers in the surface soil and reduced levels of organic matter, especially in the subsurface layer.

Additional keywords: aggregate stability, clay dispersion, organic carbon, soil conservation.


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