AbstractsBiology & Animal Science

Tillage effects on soil respiration in Swedish arable soils

by Veera Kainiemi




Institution: Swedish University of Agricultural Sciences
Department:
Year: 2014
Keywords: tillage; arable soils; crop residues; soil structure; soil respiration; organic matter; degradation; carbon mineralization; soil water content; soil temperature; sweden; soil respiration; tillage; soil structure
Record ID: 1359565
Full text PDF: http://pub.epsilon.slu.se/10961/


Abstract

The amount of carbon (C) present in soil is greater than the sum of C present in terrestrial vegetation and the atmosphere combined. Small changes in soils can therefore affect atmospheric CO₂ levels and ultimately the global climate. Soil C is also one of the main soil properties involved in several soil functions critical for soil productivity. Mechanical disturbance of the soil, e.g. through tillage, can influence soil C and has been the focus of much research. However, the mechanisms behind C mineralisation are still not completely understood and research results vary. Tillage affects the availability of organic material for decomposers, the soil structure and the activity of soil organisms, which are also affected by changes in soil moisture and temperature. This thesis examined the effects of different tillage practices on short-term soil respiration and changes in soil structure, moisture and temperature and the effects on C mineralisation in soils. It also quantified potential soil respiration resulting from mechanical disturbance in different Swedish arable soils. In order to unravel the mechanisms involved, experiments were carried out in the field and under controlled conditions in the laboratory. The response of soil respiration to different tillage treatments and plant residue managements was measured in the field and changes in soil structure, moisture and temperature were recorded and related to soil respiration. In the laboratory, soils of different textures were subjected to mechanical disturbance at different water contents and potential soil respiration was measured. The field studies showed that mouldboard ploughing decreased soil respiration by up to 340 kg ha⁻¹ compared with no tillage and 140 kg ha⁻¹ compared with shallow tillage during the 10 days following tillage, after which the differences were negligible. Soil temperature and water content did not significantly affect soil respiration in the field. Furthermore, mouldboard ploughing produced most large aggregates (>64 mm), corresponding to about 90% of soil mass in the tilled layer and resulted also in the lowest soil respiration. The potential soil respiration following physical disturbance at a controlled water content and temperature resulted in C losses of up to 74 kg ha⁻¹ in the laboratory, indicating that increasing clay content and water content can increase the risk of C losses from soils due to mechanical disturbance. However, under field conditions, the mechanisms behind C mineralisation following tillage are primarily determined by residue management rather than by soil structure or changes in soil moisture and temperature.