Effect of long-term tillage treatments on the temporal dynamics of water-stable aggregates and on macro-aggregate turnover at three German sites

• Published in: Geoderma Vol. 217-218; pp. 57 - 64
• Main Authors: Andruschkewitsch, Rouven, Koch, Heinz-Josef, Ludwig, Bernard
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.04.2014; Elsevier
• Subjects: Aggregate dynamics; Aggregate turnover; Aggregates; Agronomy. Soil science and plant productions; Biological and medical sciences; Carbon content; Cropping systems. Cultivation. Soil tillage; Earth sciences; Earth, ocean, space; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; Litter; Long-term tillage; Sampling; Soil (material); Soil organic matter; Soil tillage; Soils; Sugar beets; Surficial geology; Tillage; Tillage. Tending. Growth control; Wheat; Europe; Germany; Soil organic matter; Aggregate dynamics; Long-term tillage; Aggregate turnover; Microbial activity; Organic carbon; Organic matter; Structure stability; Soil tillage; Stabilization; Decomposition; Zero tillage; Dimension spectrum; Time variation; Plowing; Soils; Treatment; Conventional tillage; Turnover; Organic material; Sugar beet; Mulching; Protection
• ISSN: 0016-7061; 1872-6259
• DOI: 10.1016/j.geoderma.2013.10.022

The protection of organic material within aggregates against microbial decomposition is regarded as an important process in soil organic carbon stabilization but detailed knowledge about this process is still lacking. The objective of our study was to determine the longer and short-term impacts of three different tillage treatments (conventional tillage, mulch tillage and no-tillage) on water stable aggregate size distribution. Soils from three sites with long-term tillage trials on loess soils in Germany, planted with sugar beet followed by two years of winter wheat, were sampled in 0–5cm, 5–25cm and 25–40cm depth in April 2010 (wheat stand on all sites), September 2011 (before tillage, after wheat harvest or in the sugar beet), November 2011 (bare soil after tillage or after tillage and sowing of winter wheat) and April 2012 (bare soil or wheat stand). Generally, the soils under no tillage and mulch tillage showed higher yields of macro-aggregates and carbon contents of macro-aggregates in 0–5cm soil depth than under conventional tillage for all sampling dates, probably mainly due to litter accumulation in the topsoil under reduced tillage treatments. Tillage in November 2011 showed no effect on macro-aggregate yield in comparison to earlier sampling in September 2011. This suggests that either the physical impact of the mouldboard plough did not markedly affect macro-aggregate dynamics or that high macro-aggregate rebuilding rates due to litter incorporation and soil mixing under conventional tillage counterbalanced the physical impact. In 0–5cm soil depth the carbon content of the micro-aggregates within macro-aggregates was higher under reduced tillage treatments, indicating accelerated macro-aggregate turnover under conventional tillage. In contrast, it was lower in 5–25cm under no tillage and 25–40cm under mulch tillage and no tillage than under conventional tillage. Overall, the pattern of yields of macro-aggregates and carbon contents within macro-aggregates over time and depth suggests that the interaction of soil disturbance and litter incorporation of the different tillage treatments created a steady state in terms of macro-aggregate turnover within the different tillage treatments. •Soils from 3 sites with long-term tillage trials were sampled on 4 dates.•Tillage affected yields of macro-aggregates in surface soils.•Tillage affected carbon contents of macro-aggregates in surface soils.