Impact of mechanically pre-treated anaerobic digestates on soil properties

• A Voelkner ^[2] ; S Ohl ^[3] ; D Holthusen ^[2] ; E Hartung ^[3] ; J Dörner ^[1] ; R Horn ^[2]
  1. [1] Universidad Austral de Chile

     Universidad Austral de Chile

     Valdivia, Chile

     
  2. [2] University of Kie Institute of Plant Nutrition and Soil Science
  3. [3] University of Kie Institute of Agricultural Engineering

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• Localización: Journal of soil science and plant nutrition, ISSN-e 0718-9516, ISSN 0718-9508, Vol. 15, Nº. 4, 2015, págs. 882-895
• Idioma: inglés
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• Resumen

  • The production of biogas by anaerobic digestion results in the production of digestates, which are intended to be used as organic fertilizer in agriculture. However, these anaerobic digestates (AD) - besides having benefits for the nutrient status of soils - are assumed to have adverse consequences for soil properties. It is thus the objective of this study to determine the effects of 30 m³ ha-1 of AD´s on pH, electrical conductivity (EC), and the wetting behavior determined by the Repellency Index (RI) and the contact angle (CA) of a loamy Cambic Luvisol and a sandy Podzol. The AD´s, derived from mechanically pre-treated (grinding/chopping) input substrates (IS) from maize (Zea mays L.) and sugar beet (Beta vulgaris L.) in variable shares (100 %, 80 % / 20 %), were mixed with homogenized (sieved to ≤ 2 mm) soils by stirring. Blending of the AD increased the EC significantly and induced more alkaline conditions; the extent of this change was highly dependent on soil texture. The use of AD derived from ground IS resulted in more hydrophobic conditions compared to AD from chopped IS. This leads in the current study to the conclusion that the mechanical pre-treatment of the IS for anaerobic digestion and also the soil texture are decisive factors controlling both the physicochemical and the hydraulic effects of digestates to the soils.