| 1. |
- Kainiemi, Veera, et al.
(författare)
-
Effects of autumn tillage and residue management on soil respiration in a long-term field experiment in Sweden
- 2015
-
Ingår i: Journal of Plant Nutrition and Soil Science. - : Wiley. - 1436-8730 .- 1522-2624. ; 178, s. 189-198
-
Tidskriftsartikel (refereegranskat)abstract
- Several previous field studies in temperate regions have shown decreased soil respiration after conventional tillage compared with reduced or no-tillage treatments. Whether this decrease is due to differences in plant residue distribution or changes in soil structure following tillage remains an open question. This study investigated (1) the effects of residue management and incorporation depth on soil respiration and (2) biological activity in different post-tillage aggregates representing the actual size and distribution of aggregates observed in the tilled layer. The study was conducted within a long-term tillage experiment on a clay soil (Eutric Cambisol) in Uppsala, Sweden. After 38 y, four replicate plots in two long-term treatments (moldboard plowing (MP) and shallow tillage (ST)) were split into three subplots. These were then used for a short-term trial in which crop residues were either removed, left on the surface or incorporated to about 6 cm depth (ST) or at 20 cm depth (MP). Soil respiration, soil temperature, and water content were monitored during a 10-d period after tillage treatment. Respiration from aggregates of different sizes produced by ST and MP was also measured at constant water potential and temperature in the laboratory. The results showed that MP decreased short-term soil respiration compared with ST or no tillage. Small aggregates (< 16 mm) were biologically most active, irrespective of tillage method, but due to their low proportion of total soil mass they contributed < 1.5% to total respiration from the tilled layer. Differences in respiration between tillage treatments were found to be attributable to indirect effects on soil moisture and temperature profiles and the depth distribution of crop residues, rather than to physical disturbance of the soil.
|
|
| 2. |
- Kainiemi, Veera, et al.
(författare)
-
Short-term organic matter mineralisation following different types of tillage on a Swedish clay soil
- 2013
-
Ingår i: Biology and Fertility of Soils. - : Springer Science and Business Media LLC. - 0178-2762 .- 1432-0789. ; 49, s. 495-504
-
Tidskriftsartikel (refereegranskat)abstract
- Reduced tillage is proposed as a method of C sequestration in agricultural soils. However, tillage effects on organic matter turnover are often contradictory and data are lacking on how tillage practices affect soil respiration in northern Europe. This field study (1) quantified the short-term effects of different tillage methods and timing on soil respiration and N mineralisation and (2) examined changes in aggregate size distribution due to different tillage operations and how these relate to soil respiration. The study was conducted on Swedish clay soil (Eutric Cambisol) and compared no-tillage with three forms of tillage applied in early or late autumn 2010: mouldboard ploughing to 20-22 cm and chisel ploughing to 12 or 5 cm depth. Soil respiration, soil temperature, gravimetric water content, mineral N and aggregate size distribution were measured. The results showed that respiration was significantly higher (P < 0.001) in no-till than in tilled plots during the 2 weeks following tillage in early September. Later tillage gave a similar trend but treatments did not differ significantly. Soil tillage and temperature explained 56 % of the variation in respiration. In the early tillage treatment, soil respiration decreased with tillage depth. Mineral N status was not affected by tillage treatment or timing. Soil water content did not differ significantly between tillage practices and therefore did not explain differences in respiration. The results indicate that conventional tillage in early autumn may reduce short-term soil respiration compared with chisel ploughing and no-till in clay soils in northern Europe.
|
|
| 3. |
|
|
| 4. |
- Kainiemi, Veera, et al.
(författare)
-
Structural disruption of arable soils under laboratory conditions causes minor respiration increases
- 2016
-
Ingår i: Journal of Plant Nutrition and Soil Science. - : Wiley. - 1436-8730 .- 1522-2624. ; 179, s. 88-93
-
Tidskriftsartikel (refereegranskat)abstract
- Previous field studies in N Europe have shown that the impact of soil tillage on soil respiration is mostly indirect, caused by altered distribution of plant residues in soil affecting decomposition of residues. Tillage operations alter soil moisture and temperature conditions in soil, which control decomposition dynamics. Experiments under laboratory conditions allow indirect effects of altered residue decomposition to be distinguished from direct effects of mechanical disruption, i. e., the increased exposure of substrates within aggregates and micropores upon tillage. This study examined the effects of physical disruption of soils with different soil texture, land-use history, and soil organic C content on soil respiration under controlled abiotic conditions. Undisturbed soil samples from 7 sites (arable land and grassland) were incubated at 20 degrees C and three different water potentials (-1, -10, and -30 kPa). Soil respiration was measured before and after physical disruption with laboratory homogenizer, using an automated respiration apparatus. Soil organic C, water content, and bulk density explained 67% of the variation in base respiration. In half of the disrupted samples, bulk density was re-adjusted by re-compaction to conditions prevailing before disruption. Disruption and re-compaction generally resulted in higher respiration flushes than disruption alone. Respiration peaks increased with water content. However, total C losses were small and corresponded to < 0.1 Mg C ha(-1). Overall, physical soil disruption increased decomposition of soil organic matter only marginally and temporarily. It would be difficult to detect an effect of tillage on soil organic matter decomposition under field conditions.
|
|
| 5. |
- Kainiemi, Veera
(författare)
-
Tillage effects on soil respiration in Swedish arable soils
- 2014
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)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.
|
|
