24.3.2014: Forschung CH

Biodiversität im Ackerboden

La biodiversité des sols cultivés


Marianne Kuntz et al.

Bodenorganismen bilden eine wesentliche Grundlage der Bodenfruchtbarkeit. Die Art der Bodenbearbeitung von Ackerböden beeinflusst die Bodenorganismen massgeblich. Eine Reduzierung der Bodenbearbeitung erhöht die Funktionen der Bodenfauna und bietet damit einen Ansatz für die Öko-Intensivierung. Dies wurde in einem Langzeit-Versuch in einer 6-jährigen Fruchtfolge mit biologischer Bewirtschaftung aufgezeigt.

Les organismes du sol sont fondamentaux pour la fertilité des sols. Le travail du sol dans les champs cultivés influence de façon significative la faune du sol. Une réduction du travail du sol améliore les fonctions inhérentes à la faune du sol et conduit à une éco-intensification. C’est ce qu’un essai de longue durée en culture biologique a pu mettre en évidence dans une rotation des cultures de 6 ans.


Although reduced tillage is an agricultural practice reported to decrease soil erosion and external inputs while enhancing soil fertility, it has still rarely been adopted by European organic farmers. The objective of this study was to assess the long-term interactive effects of tillage (conventional (CT) vs. reduced (RT)) and fertilization (slurry (S) vs. composted manure/slurry (MCS)) on earthworms and microbial communities in a clay soil under spelt in an organic 6-year crop rotation. Earthworm populations (species, density and biomass, cocoons) were investigated by handsorting the soil nine years after initial implementation of the treatments. Soil microbial carbon (Cmic) and nitrogen (Nmic) were measured by chloroform-fumigation extraction and a simplified phospholipid fatty acid (PLFA) analysis was used to separate for populations of bacteria, fungi and protozoa.
Significantly increased total earthworm density in RT plots was mainly attributed to increased numbers of juveniles. Moreover, we found five times more cocoons with RT. Species richness was not affected by the treatments, but tillage treatments had differentially affected populations at the species-level. In addition, cluster analysis at the community level revealed two distinct groups of plots in relation to tillage treatments. In RT plots Cmic increased in the 0–10 cm and 10–20 cm soil layers, while PLFA concentrations indicative of Gram-negative bacteria, fungi and protozoa only increased in the topsoil. Lower bacteria-to-fungi ratios in the upper soil layer of RT plots indicated a shift to fungalbased decomposition of organic matter whereas a higher Cmic-to-Corg ratio pointed towards enhanced substrate availability. Slurry application decreased microbial biomass and enhanced density of juvenile anecic earthworms but overall fertilization effect was weak and no interactions with tillage were found. In conclusion, tillage is a major driver in altering communities of earthworms and microorganisms in arable soils. The use of reduced tillage provides an approach for eco-intensification by enhancing inherent soil biota functions under organic arable farming.

Quelle: FIBL


Keywords:
Landwirtschaft, biologischer Landbau, Bodenbearbeitung, Bodenfruchtbarkeit, Regenwürmer

Art der Publikation:
Fachpublikation

Literatur:
Kuntz M. et al. (2013): Influence of reduced tillage on earthworm and microbial communities under organic arable farming. Pedobiologia 56, 251-260.
http://www.fibl.org



Kontaktadresse:
Dr. Lukas Pfiffner
Research Institute of Organic Agriculture (FiBL)
Department Crop Sciences
Agroecology and Biodiversity
Ackerstrasse 113, Box 219
CH-5070 Frick

lukas.pfiffner@fibl.org
Tel: +41 (0)62 865 72 46


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