| 1. |
- 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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| 2. |
- MacLaren, Chloe, et al.
(författare)
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Long-term evidence for ecological intensification as a pathway to sustainable agriculture
- 2022
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Ingår i: Nature Sustainability. - : Nature Research. - 2398-9629. ; 5, s. 770-
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Tidskriftsartikel (refereegranskat)abstract
- Ecological intensification (EI) could help return agriculture into a ‘safe operating space’ for humanity. Using a novel application of meta-analysis to data from 30 long-term experiments from Europe and Africa (comprising 25,565 yield records), we investigated how field-scale EI practices interact with each other, and with N fertilizer and tillage, in their effects on long-term crop yields. Here we confirmed that EI practices (specifically, increasing crop diversity and adding fertility crops and organic matter) have generally positive effects on the yield of staple crops. However, we show that EI practices have a largely substitutive interaction with N fertilizer, so that EI practices substantially increase yield at low N fertilizer doses but have minimal or no effect on yield at high N fertilizer doses. EI practices had comparable effects across different tillage intensities, and reducing tillage did not strongly affect yields. © 2022, The Author(s)
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| 3. |
- Colombi, Tino, et al.
(författare)
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Developing strategies to recover crop productivity after soil compaction-A plant eco-physiological perspective
- 2019
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Ingår i: Soil and Tillage Research. - : Elsevier BV. - 0167-1987 .- 1879-3444. ; 191, s. 156-161
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Tidskriftsartikel (refereegranskat)abstract
- Soil compaction constitutes a major threat to the fertility of arable soils and food security. The aim of this paper is to highlight the need and opportunities for plant eco-physiological approaches to identify strategies to recover crop yields after soil compaction. Reduced productivity on compacted soil primarily results from decreased root elongation rates and thus limited accessibility to water and nutrients. Hence, strategies to recover productivity after compaction must address plant eco-physiological phenomena that underlie low root system expansion rates. In compacted soil, root growth is decreased due to high soil penetration resistance and due to low oxygen concentration in soil air caused by reduced fluid transport capability. Thus, plant roots are exposed to a multi-stress environment, which needs to be addressed directly when aiming to recover productivity after compaction in the long-term. Here, we discuss possibilities to increase root growth in order to enhance resource accessibility and recover crop productivity on compacted soil. Yield recovery can be achieved through breeding of novel cultivars and targeted soil management approaches. On the one hand, the tolerance of plants to the different soil physical stresses can be enhanced by selecting for specific root traits that facilitate root growth in compacted soil. Soil management approaches that improve specific physical properties of compacted soil on the other hand can facilitate root growth in compacted soil. Since plant roots are major drivers of soil structure dynamics, increasing root growth in compacted soil may not only mitigate crop productivity losses but also recover soil structure.
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| 4. |
- Daverkosen, Lærke Lil Munck, et al.
(författare)
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The potential of regenerative agriculture to improve soil health on Gotland, Sweden
- 2022
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Ingår i: Journal of Plant Nutrition and Soil Science. - : Wiley. - 1436-8730 .- 1522-2624.
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Tidskriftsartikel (refereegranskat)abstract
- Background Regenerative agriculture has gained attention in mainstream media, academic literature, and international politics in recent years. While many practices and outcomes relate to RA, there is no uniform definition of the term, and only a few comprehensive scientific studies exist of "real-life" farms and the complexity of what is considered regenerative management and its impact on soil health. Aims This study aimed to relate the impact of single and various combinations of regenerative management practices to soil health indicators on Gotland, Sweden. Methods Soil health of 17 farm fields and six gardens was assessed on 11 farms that had applied regenerative agricultural practices for zero to 30 years. We measured a variety of physical (bulk density , infiltration rate, wet aggregate stability, root depth and abundance, penetration resistance), chemical (pH, electric conductivity, C:N ratio, total organic carbon ) and biological (earthworm abundance, active carbon, microbial biomass carbon) soil indicators. These parameters were related to regenerative practices (reduced tillage, application of organic matter , livestock integration, crop diversity, and share of legumes and perennials) through a combination of hierarchical clustering, Analysis of Variance and Tukey's tests, principal component analysis, and multiple linear regressions. Results At our study sites, the application of organic matter had a positive impact on bulk density, carbon-related parameters, wet aggregate stability, and infiltration rate, while reduced tillage and increased share of perennials combined had a positive impact on vegetation density, root abundance and depth, and wet aggregate stability. The field plots were divided into four clusters according to their management, and we found significantly higher values of total organic carbon (*), C:N (*), infiltration rate (**), and earthworm abundance (*) for crop-high-org-input, the management cluster with highest values of organic matter application and no tillage. We found significantly higher values of vegetation density (***) and root abundance (**) for perm-cover-livestock, the cluster with no tillage, integration of livestocks, and permanent cover (*** p < 0.001, ** p < 0.01, *p < 0.05, degrees p > 0.1). Conclusions We support existing knowledge on positive impacts of regenerative practices, namely, the addition of an organic amendment that improved C-related parameters, as well as the positive effects on soil structure of reduced tillage in combination with an increased share of perennials. We argue for an outcome-based, and principle-led concept of RA as a context-dependent agricultural approach.
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| 5. |
- Getahun, Gizachew Tarekegn, et al.
(författare)
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Short-term effects of loosening and incorporation of straw slurry into the upper subsoil on soil physical properties and crop yield
- 2018
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Ingår i: Soil and Tillage Research. - : Elsevier BV. - 0167-1987 .- 1879-3444. ; 184, s. 62-67
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Tidskriftsartikel (refereegranskat)abstract
- Subsoils that are compacted, nutrient-poor or low in soil organic matter (SOM) often limit crop growth and yield. Improvement of subsoil conditions by deep loosening is laborious and expensive and its positive effect may not last. This study investigated the effect of deep loosening and injection of slurry made from cereal straw (30 Mg dry mass ha(-1)) at 25-34 cm depth on soil properties and crop performance in a Swedish field experiment that started in autumn 2015 and monitored soil and crop properties during 2016. Loosening + straw incorporation into subsoil resulted in significantly higher soil organic carbon (SOC) content, potential plant-available water and porosity and lower bulk density (BD) in spring 2016 compared with the control. In autumn 2016, penetrometer resistance (PR) and BD were both significantly lower and SOC and porosity were significantly higher in the loosening + straw treatment compared with the control and loosening only (29-34 cm). Furthermore, BD was significantly lower in the loosening + straw treated subsoil than in the top soil layer of the control (0-10 cm). Observations indicated that more continuous pores were found in the loosening + straw treatment than in other treatments. Roots and soil faunas were found more frequently where straw was incorporated. Grain yield increased by 5.6% due to loosening + straw addition (P = 0.03) and by 4% due to loosening only (P = 0.06). These results indicate that loosening + straw input into upper subsoil had a positive short-term influence on soil physical properties, potential plant-available water and grain yield. Straw addition prolonged the positive effect of loosening.
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| 6. |
- Håkansson, Inge, et al.
(författare)
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Effects of sedbed properties on crop emergence. 4. Inhibitory effect of oxygen deficiency
- 2012
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Ingår i: Acta Agriculturae Scandinavica, Section B - Soil and Plant Science. - : Informa UK Limited. - 0906-4710 .- 1651-1913. ; 62, s. 166-171
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Tidskriftsartikel (refereegranskat)abstract
- For studies of the effects of seedbed properties on crop emergence, experiments were carried out in shallow plastic boxes. In some experiments, it was examined whether rainfall after sowing could cause oxygen deficiency in the seedbed sufficiently severe to hamper emergence. Crops studied were barley (Hordeum vulgare L.), wheat (Triticum aestivum L.), oilseed rape (Brassica napus var. oleifera, L., Metzg.) and pea (Pisum sativum L.). For harmful oxygen deficiency to develop it appeared that rainfall would need to cause structural collapse of the surface layer followed by continuously wet weather accompanied by slow drainage and high oxygen consumption in the soil; in the experiments the latter was achieved by large amounts of easily decomposable organic matter. It was concluded that such conditions are rare in the field. Therefore, unless rainfall after sowing generates surface water for an extended period, the poor crop emergence often observed after such rainfall is nearly always caused not by oxygen deficiency, but by surface layer hardening when this layer dries.
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| 7. |
- Håkansson, Inge, et al.
(författare)
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Effects of seedbed properties on crop emergence. 6. Requirements of crops with small seeds
- 2013
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Ingår i: Acta Agriculturae Scandinavica, Section B - Soil and Plant Science. - : Informa UK Limited. - 0906-4710 .- 1651-1913. ; 63, s. 554-563
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Tidskriftsartikel (refereegranskat)abstract
- The effects of seedbed properties on emergence of various crops were studied in a series of experiments. Results for crops with seeds weighing <7 mg are reported here. The experiments were carried out in shallow plastic boxes placed directly on the ground in the field. Small seeds require shallow sowing, which is a great disadvantage in the event of dry weather after sowing, particularly on clay and clay loam soils, where the upper 3-cm soil layer quickly dries to wilting point. Nevertheless, good emergence of crops with seeds weighing 2-7 mg (white mustard, Sinapis alba L., oilseed rape, Brassica rapa L., Metzg., sugar beet, Beta vulgaris L. and red clover, Trifolium pratense L.) was often obtained when the seed was placed at about 3-cm depth directly on a firm basal layer with >6% plant-available water and covered by soil dominated by aggregates <5 mm. Cruciferous crops germinated most rapidly, which facilitated emergence from shallow depth. Sowing could be slightly shallower in coarse-textured than in fine-textured soils, since the former soils dry less rapidly to below wilting point. For timothy (Phleum pratense L.) with seeds weighing about 0.5 mg and requiring a sowing depth <2.5 cm, it was impossible to design a seedbed that eliminated the risk of poor emergence in dry weather. Firming of the seedbed after sowing favoured emergence only in initially dry seedbeds. The risk of poor emergence because of surface layer hardening was minimised by placing seeds at a depth and in seedbed conditions that promoted the fastest possible emergence.
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| 8. |
- Keller, Thomas
(författare)
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A Meta-analysis of Soil Susceptibility to Machinery-Induced Compaction in Forest Ecosystems Across Global Climatic Zones
- 2023
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Ingår i: Current Forestry Reports. - 2198-6436. ; 9, s. 370-381
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Forskningsöversikt (refereegranskat)abstract
- Purpose of Review Predicting, preventing, and minimizing machinery-induced soil compaction are of paramount importance in forest ecosystems. Understanding the soil's susceptibility to compaction is crucial in achieving these goals. This meta-analysis assessed the relevance of climatic and soil conditions for the susceptibility of forest soils to wood-harvesting-associated compaction across global climatic zones. We utilized soil bulk density change data (effect sizes; compacted versus uncompacted) from 81 forest sites worldwide, and mapped global patterns of the susceptibility of forest soils to compaction using climate and soil data.Recent Findings Wood-harvesting operations by harvester-forwarder technologies disturb the soil less as compared to skidders and cable yarders. It has been shown that a high number of vehicle passages (> 20 times) lead to maximum soil damage, although this contradicts the general belief that major soil disturbance occurs within the first few vehicle passages. Despite these important findings, a global compilation of local information on forest soil compaction induced by mechanized wood harvesting is currently lacking. A map that illustrates the global pattern of soil susceptibility to compaction is also required to identify particularly susceptible forest regions.Summary Forest soils in tropical and temperate zones were most susceptible to compaction (48% and 30% bulk density increase, respectively), while forest soils in arid and cold zones were less susceptible (15% and 18% bulk density increase, respectively). Soils in tropical and temperate forests receive high annual precipitation amounts, are characterized by high soil organic carbon content and low bulk density, and are often wet, resulting in high susceptibility to compaction. Since tropical and temperate forests are biodiversity hotspots, forest managers and policymakers should pay particular attention to mechanized wood-harvesting operations in these zones, as the recovery of compacted forest soils requires decades.
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| 9. |
- Keller, Thomas
(författare)
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Advances in Cotton Harvesting Technology: a Review and Implications for the John Deere Round Baler Cotton Picker
- 2015
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Ingår i: Journal of Cotton Science. - 1523-6919 .- 1524-3303. ; 19, s. 225-249
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Forskningsöversikt (refereegranskat)abstract
- To address the progressive increase in farmed land and the decline in labor, cotton production in more developed agricultural systems has seen a movement towards larger, heavier machinery with increased capacity. Recent innovation of on-board module building technology for cotton harvesters follows this trend, which has caused concern for the potential impact of the machine on the farming system. This review acknowledges past and present developments within the cotton harvesting system from both the machine- and soil-management perspectives to inform land managers, machinery manufacturers, technical advisors, and the scientific community of the incidence of soil compaction associated with technology uptake in cotton-based systems. Emphasis is made on the need to ensure that the effects of traffic-induced soil compaction are minimized. For this, the feasibility of confining compaction to the least possible area of permanent traffic lanes is examined along with engineering design constraints of commercially available cotton pickers. Fundamental information is elicited, which provided insights as to why this movement has occurred and how associated problems might be addressed. Within the Australia context, these cotton harvesters have undergone rapid adoption. This review uses this case-study to elucidate direct and latent impacts of the machine to help identify risks and develop management strategies as further technology is developed and adopted.
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| 10. |
- Keller, Thomas
(författare)
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Analysis of soil compression curves from uniaxial confined compression tests
- 2011
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Ingår i: Geoderma. - : Elsevier BV. - 0016-7061 .- 1872-6259. ; 163, s. 13-23
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Tidskriftsartikel (refereegranskat)abstract
- The compressive behaviour of soil, the compression curve, is typically expressed in a semi-logarithmic diagram in the relationship between the logarithm of applied stress, sigma, and the void ratio, e. The compression curve yields three important soil compression properties: the swelling index. C(s), the compression index, C(c), and the precompression stress, sigma(pc). The compression index is considered an indicator of soil resistance to compaction, C(s) is used as a measure of soil mechanical resilience, and sigma(pc) is considered the soil load support capacity. The objective of this paper was to investigate the impact of soil particle and aggregate size distribution on the characteristics of the soil compression curve and on C(s), C(c), and sigma(pc) for a range of Swedish soils. We found no or only weak impacts of particle size and aggregate size distribution on soil compression properties. Instead, soil compression properties were largely controlled by initial void ratio, e(0), in such a way that Q and C, decreases, and sigma(pc) increases with decreasing e(0), although the correlation between sigma(pc) and e(0) was not statistically significant for subsoil samples. We show that the soil compression properties (sigma(pc), C(c) and C(s)) and their dependency upon e(0) are partly a consequence of the compression curve being analyzed in a semi-logarithmic (log sigma-e) diagram. The use of log sigma( instead of sigma) forces the compression curve to bend at a certain value of log sigma, and this bend is associated with sigma(pc). We showed that a precompression stress, as commonly defined, can be obtained for an ideal linear-elastic material. Therefore, the use of a logarithmic stress scale may lead to misinterpretation of soil mechanical behaviour. Our empirical results and theoretical exercise emphasize the need for further studies of physically-based expressions for soil strength for use in compaction modelling. (C) 2011 Elsevier B.V. All rights reserved.
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