| 1. |
- Arrazola Vasquez, Elsa, et al.
(författare)
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Earthworm burrowing modes and rates depend on earthworm species and soil mechanical resistance
- 2022
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Ingår i: Applied Soil Ecology. - : Elsevier BV. - 0929-1393 .- 1873-0272. ; 178
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Tidskriftsartikel (refereegranskat)abstract
- Earthworms drive multiple soil processes, but their specific impact on soil functions differs between earthworm species and ecological categories. A key challenge in modern agriculture is soil compaction due to heavy ma-chinery, but we have limited quantitative knowledge about how the burrowing activity of different earthworm species is affected by compaction. Here, we address this question in a laboratory experiment with 2-D terraria, where we used Aporrectodea caliginosa (Savigny, 1826) and Aporrectodea longa (Ude, 1885) as representatives of two different ecological categories. We exposed both species to four different soil mechanical resistance levels and monitored their burrowing activity for three days. We quantified burrowing rates and cast production, assessed the burrowing mode, and estimated energy requirements as a function of soil mechanical resistance. The results showed that the burrowing rates of both earthworm species significantly decreased with increasing soil mechanical resistance, but that the impact was species-dependent and lower for A. longa. Earthworms changed their burrowing mode towards ingestion when soil mechanical resistance increased, and this shift was more prominent for A. caliginosa that primarily burrowed via cavity expansion (i.e. by pushing soil aside) at low soil mechanical resistance. We further show that energy requirement and cast produced per unit burrow length increased with soil mechanical resistance. Our study revealed significant and species-dependent adverse effects of soil mechanical resistance on earthworm burrowing, which in turn has consequences for many soil processes mediated by earthworms, such as water infiltration, soil aeration, nutrient cycling and soil organic matter turnover.
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| 2. |
- Arvidsson, Johan, et al.
(författare)
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Comparing penetrometer and shear vane measurements with measured and predicted mouldboard plough draught in a range of Swedish soils
- 2011
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Ingår i: Soil and Tillage Research. - : Elsevier BV. - 0167-1987 .- 1879-3444. ; 111, s. 219-223
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Tidskriftsartikel (refereegranskat)abstract
- Soil strength proved much more sensitive to changes in water content than draught requirement. Consequently, model predictions of specific draught were much higher than measured values in soil with high cohesion values. A possible explanation is that specific draught mainly depends on inter-aggregate strength, while the intra-aggregate strength may be considerably higher. Over all tillage occasions, specific draught was much more strongly correlated to cohesion than to penetration resistance. There was also a clear correlation between draught and soil clay content. Multiple regression including cohesion and soil water content resulted in a much higher coefficient of determination than regression with cohesion only. The results indicate that neither shear vane nor penetrometer measurements are sufficient to predict draught requirement, and it is desirable to develop a simple yet reliable field method that can be used for this purpose. More general estimates of fuel consumption can probably be made based on the soil clay content only. (C) 2010 Elsevier B.V. All rights reserved.
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| 3. |
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| 4. |
- Arvidsson, Johan, et al.
(författare)
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Draught requirement during tillage
- 2010
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Ingår i: Soil Engineering. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 9783642036804 ; 20:20, s. 3-17
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 5. |
- Arvidsson, Johan, et al.
(författare)
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Rubber track systems for conventional tractors : Effects on soil compaction and traction
- 2011
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Ingår i: Soil & Tillage Research. - : Elsevier BV. - 0167-1987 .- 1879-3444. ; 117, s. 103-109
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Tidskriftsartikel (refereegranskat)abstract
- Traditionally, tractors have been built either for tracks or wheels, with tracks mainly on heavy tractors with high power. Today, it is possible to retrofit four separate track units on a conventional agricultural tractor, creating interesting possibilities for agriculture. The objective of the present study was to compare soil compaction and traction for tracks, single and dual wheels mounted on the same tractor type. Measurements were made on two clay soils (Eutric Cambisols) in Sweden in 2009, using an 85kW tractor with a total weight of 7700kg. The rubber track system consisted of four tracks mounted on the conventional wheel axles of the tractor. The measured stresses were similar for the tracks and dual wheels at all depths studied (15, 30 and 50cm), but were considerably higher for the single wheels at all depths. Simulations of soil stresses correlated closely to measured values for the tracks and the dual wheels, but underestimated soil stresses in the topsoil compared to measured values for the single wheel. Bulk density and penetration resistance were consistently highest and saturated hydraulic conductivity lowest after wheeling with single wheels, while there were no statistically significant differences between tracks and dual wheels. With single wheels and the tractor loaded, saturated hydraulic conductivity decreased to 0.01mh-1 from 0.13mh-1 in the control, while bulk density increased from 1.24 to 1.36Mgm-3. The stress distribution in the driving direction was relatively even along the front and rear tracks, which is an advantage compared with a long single track, which often has an uneven longitudinal stress distribution. Slip was significantly higher for the dual and single wheels compared with tracks. To utilise the large contact area of the tracks, the tractor should have a low weight in relation to the engine power. © 2011 Elsevier B.V.
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| 6. |
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| 7. |
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| 8. |
- Blomquist, Jens, et al.
(författare)
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Structure liming reduces draught requirement on clay soil
- 2023
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Ingår i: Soil and Tillage Research. - 0167-1987 .- 1879-3444. ; 231
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Tidskriftsartikel (refereegranskat)abstract
- Liming with ‘structure lime’, comprising approximately 80–85% ground limestone and 15–20% slaked lime, has been promoted in subsidised environmental schemes in Sweden since 2010 to increase clay aggregate stability and mitigate particulate phosphorus losses to surface waters. To date, approximately 65,000 ha have been structure-limed. Apart from stabilising aggregates, liming may also improve other physical properties, such as soil strength. This study examined the effect of increasing application rate (0–16 t ha-1) of structure lime on soil strength, approximated by horizontal (draught requirement) and vertical (penetrometer resistance) measurements, in eight field soils (clay content 26–38%) to which structure lime had been applied two, three, four or six years previously. Draught requirement when cultivating with a multipurpose cultivator significantly decreased (by 11%) with the highest application rate of structure lime (16 t ha-1) compared with an unlimed control. This reduced the wheel power requirement by 7.1 kW and diesel consumption by 1.2–1.4 L ha-1, and lowered CO2 emissions by 3–4 kg ha-1. To clarify the general effect of structure liming, the mean value of all limed treatments was compared with that of the unlimed control. This showed that structure liming in general significantly reduced the draught requirement (by 7%). However, penetrometer resistance measurements revealed no significant effects of structure liming and no relation between draught requirement and penetrometer resistance measurements. Overall, the results indicate that structure liming can reduce fuel consumption, due to easier soil tillage, and thus lower CO2 emissions.
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| 9. |
- Bölenius, Elisabeth, et al.
(författare)
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Can within field yield variation be explained using horizontal penetrometer resistance and electrical conductivity measurements? Results from three Swedish fields
- 2018
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Ingår i: Acta Agriculturae Scandinavica, Section B - Soil and Plant Science. - : Informa UK Limited. - 0906-4710 .- 1651-1913. ; 68, s. 690-700
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Tidskriftsartikel (refereegranskat)abstract
- Spatial variations in yield occur in all agricultural fields to some degree. Knowledge of the reasons for these variations, especially temporally stable yield patterns, is needed in order to improve productivity by changing production methods or inputs. This information must be provided in a simple, cost-effective way. This study investigated whether field-scale measurements of penetration resistance (PR) could identify temporally stable yield patterns without complementary measurements of other properties. The PR measurements were also compared with field-scale apparent electrical conductivity (ECa) measurements and correlations between yield and PR and yield and ECa were investigated. Measurements with a newly constructed horizontal penetrometer and a non-invasive proximal electromagnetic induction sensor were carried out in three fields in east-central Sweden. The measurements were made once in each field, apart from one field where PR was measured twice in one season. The sensor measurements were compared with crop yield measured over the course of several years. The horizontal penetrometer was able to identify low-yielding areas in one field. However, single measurements of PR or ECa were insufficient to consistently identify yield variations. Parts of the fields showed more consistent patterns, with stronger correlations between PR, ECa and yield. PR and ECa data were better at explaining yield variations in drier years, but showed diverging patterns in different fields and neither showed a much stronger correlation to yield than the other. In future studies, simultaneous measurement of soil water content is recommended and also PR measurements at a water content drier than field capacity.
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| 10. |
- Bösch, Yvonne, et al.
(författare)
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Minimizing tillage modifies fungal denitrifier communities, increases denitrification rates and enhances the genetic potential for fungal, relative to bacterial, denitrification
- 2022
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Ingår i: Soil Biology and Biochemistry. - : Elsevier BV. - 0038-0717 .- 1879-3428. ; 170
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Tidskriftsartikel (refereegranskat)abstract
- Nitrous oxide (N2O) emissions from arable soils are predominantly caused by denitrifying microbes, of which fungal denitrifiers are of particular interest, as fungi, in contrast to bacteria, terminate denitrification with N2O. Reduced tillage has been shown to increase gaseous nitrogen losses from soil, but knowledge of how varying tillage regimes and associated soil physical and chemical alterations affect fungal denitrifiers is limited. Based on results from a long-term (>40 years) tillage experiment, we show that non-inversion tillage resulted in increased potential denitrification activity in the upper soil layers, compared to annual or occasional (every 4-5 years) conventional inversion tillage. Using sequence-corrected abundance of the fungal nirK gene, we further identified an increased genetic potential for fungal denitrification, compared to that caused by bacteria, with decreasing tillage intensity. Differences in the composition and diversity of the fungal nirK community imply that different tillage regimes select for distinct fungal denitrifiers with differing functional capabilities and lifestyles, predominantly by altering carbon and nitrogen related niches. Our findings suggest that the creation of organic hotspots through stratification by non-inversion tillage increases the diversity and abundance of fungal denitrifier communities and modifies their composition, and thus their overall relevance for N2O production by denitrification, in arable soils.
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