| 1. |
- Arvidsson, Johan, et al.
(författare)
-
Rubber track systems for conventional tractors : Effects on soil compaction and traction
- 2011
-
Ingår i: Soil & Tillage Research. - : Elsevier BV. - 0167-1987 .- 1879-3444. ; 117, s. 103-109
-
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.
|
|
| 2. |
- Daverkosen, Lærke Lil Munck, et al.
(författare)
-
The potential of regenerative agriculture to improve soil health on Gotland, Sweden
- 2022
-
Ingår i: Journal of Plant Nutrition and Soil Science. - : Wiley. - 1436-8730 .- 1522-2624.
-
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.
|
|
| 3. |
- Håkansson, Inge, et al.
(författare)
-
Effects of sedbed properties on crop emergence. 4. Inhibitory effect of oxygen deficiency
- 2012
-
Ingår i: Acta Agriculturae Scandinavica, Section B - Soil and Plant Science. - : Informa UK Limited. - 0906-4710 .- 1651-1913. ; 62, s. 166-171
-
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.
|
|
| 4. |
- Håkansson, Inge, et al.
(författare)
-
Effects of seedbed properties on crop emergence. 6. Requirements of crops with small seeds
- 2013
-
Ingår i: Acta Agriculturae Scandinavica, Section B - Soil and Plant Science. - : Informa UK Limited. - 0906-4710 .- 1651-1913. ; 63, s. 554-563
-
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.
|
|
| 5. |
- Keller, Thomas
(författare)
-
Advances in Cotton Harvesting Technology: a Review and Implications for the John Deere Round Baler Cotton Picker
- 2015
-
Ingår i: Journal of Cotton Science. - 1523-6919 .- 1524-3303. ; 19, s. 225-249
-
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.
|
|
| 6. |
- Keller, Thomas
(författare)
-
Feasibility study on the potential of electrical conductivity sensor Veris (R) 3100 for field mapping of topsoil strength
- 2014
-
Ingår i: Biosystems Engineering. - : Elsevier BV. - 1537-5110 .- 1537-5129. ; 126, s. 1-11
-
Tidskriftsartikel (refereegranskat)abstract
- With advances in technology for precision agriculture, numerous attempts have been made towards development of on-the-go sensors for measuring soil compaction. Most of the on-the-go sensors developed so far have been mechanical sensors providing a soil strength parameter that can be related to degree of soil compactness. In this study, a commercial electrical conductivity sensor (Veris (R) 3100) in combination with a previously developed combined horizontal penetrometer (equipped with a dielectric sensor for water content) were tested in a field in order to examine whether the apparent electrical conductivity (ECa) within the 0-0.3 m depth (ECa-shallow) could be helpful in detecting the topsoil strength (here the horizontal penetrometer resistance). Interpolated field maps of horizontal penetrometer resistance (PR), volumetric water content (theta(v)) and ECa showed comparable patterns within some areas (but not over the field). No significant correlation (but a negative trend) was found between ECa and dry bulk density. A significant correlation between ECa and PR/theta(v), (a previously proposed water content-independent PR) was found (R-2 = 0.37, P < 0.0001). However, ECa was strongly affected by soil water content and texture. It was concluded that PR may be indirectly related to ECa through theta(v), which greatly affects both ECa and PR. The results suggested that the EC sensor could potentially be helpful for detecting zones of high soil strength (i.e. high PR/theta(v)). Further studies are suggested to address whether ECa is better related to the state of soil compaction at dry state of soil due to more significant effect of soil-soil electrical conductivity. (C) 2014 IAgrE. Published by Elsevier Ltd. All rights reserved.
|
|
| 7. |
- Keller, Thomas
(författare)
-
Improvement and field testing of a combined horizontal penetrometer for on-the-go measurement of soil water content and mechanical resistance
- 2012
-
Ingår i: Soil and Tillage Research. - : Elsevier BV. - 0167-1987 .- 1879-3444. ; 123, s. 1-10
-
Tidskriftsartikel (refereegranskat)abstract
- Soil water content has a significant effect on penetrometer resistance, so simultaneous on-the-go measurement of both these parameters can provide useful information on within-field spatial variations in soil compaction. In this study we improved and refined the electronic circuitry and mechanical construction of an existing sensor and evaluated it as a combined horizontal penetrometer in the field. This paper concentrates on its ability to determine soil water content (volumetric basis) in the field. Stationary calibration was first performed in the laboratory on remoulded loam soil (gleyic Cambisol) at gravimetric water content 0-0.28 g g(-1) and wet bulk density 1.4-1.8 g cm(-3). A quadratic relationship was found between sensor output and volumetric water content. Simulations of the sensor fringe field using a finite element model showed that at a dielectric constant of 5 (dry soil) the zone of influence of the sensor (i.e. the distance from the centre of the sensor) was approximately 70 mm, whilst at a dielectric constant of 30 (an estimate of wet soil) it was 40 mm. The dielectric sensor was then implemented together with a load cell on a tine for field measurement of water content and penetrometer resistance, and a series of transect measurements were conducted to assess its accuracy over a range of natural soil water contents in the field. Within the volumetric water content range 0.30-0.40 cm(3) cm(-3), a linear relationship fitted the sensor output versus water content data, which was in close agreement with the laboratory calibration. Additional studies on the effect of travelling speed on dielectric sensor performance showed no clear trends, but further investigations are needed. A significant negative correlation was observed between penetrometer resistance and water content. The developed combined horizontal penetrometer can be a promising useful instrument for future studies in soil compaction and precision agriculture. (C) 2012 Elsevier B.V. All rights reserved.
|
|
| 8. |
- Keller, Thomas
(författare)
-
Soil Structural Quality and Relationships With Root Properties in Single and Integrated Farming Systems
- 2022
-
Ingår i: Frontiers in Environmental Science. - : Frontiers Media SA. - 2296-665X. ; 10
-
Tidskriftsartikel (refereegranskat)abstract
- Single farming systems (SFS) such as monocultures may negatively affect soil structural quality. This study tested the hypothesis that integrated farming systems (IFS), i.e., the combination of cropping and forestry and/or livestock farming, improves soil structural quality, root development and soil organic carbon. An experimental area was set up in 2012 at the Canguiri experimental farm belonging to the Federal University of Parana, Southern Brazil. The soils are predominantly Ferralsols. The experimental treatments representing different farming systems, organized in a random block design with three replicates, were: Forestry (F), Conventional Crop Production (C), Livestock (L), and integrated Crop-Forestry (CF), Crop-Livestock (CL), Livestock-Forestry (LF), and Crop-Livestock-Forestry (CLF). In situ measurements and sampling were carried out in the 0-0.3 m layer during summer 2019/20, and included soil penetration resistance (PR), soil structural quality based on visual evaluation of soil structure (Sq(VESS) scores), root length (RL), root volume (RV) and soil organic carbon content (SOC). Soil structural quality, penetration resistance, root length and volume, and SOC varied between farming systems, but no significant differences were found between single (C, L, F) and integrated farming systems (CF, CL, LF, CLF). The single system Forestry (F) and the integrated systems including forestry (LF, CF, CLF) tended to have higher Sq(VESS) scores, i.e. poorer soil structural quality, and higher PR, which we associate with the generally drier soil conditions that are due to higher soil water uptake and higher interception and reduce the frequency of wetting-drying cycles. Roots were concentrated in the shallow soil layer (0-0.1 m depth), and this was especially pronounced in the Crop (C) single farming system. Based on the measured values, our results suggest an acceptable soil structural quality in all farming systems. Our data revealed strong, significant relationships between soil structural quality, penetration resistance, root growth and SOC, demonstrating that improvements in soil structure results in lower soil penetration resistance, higher root volumes and higher SOC, and vice versa. Soil PR was positively correlated with Sq(VESS) (R-2 = 0.84), indicating that better soil structural quality resulted in lower soil mechanical resistance. This, in turn, increased root length and volume, which increases carbon input to soil and therefore increases SOC in the long run.
|
|
| 9. |
|
|
| 10. |
- Sjulgård, Hanna, et al.
(författare)
-
Relationships between weather and yield anomalies vary with crop type and latitude in Sweden
- 2023
-
Ingår i: Agricultural Systems. - 0308-521X .- 1873-2267. ; 211
-
Tidskriftsartikel (refereegranskat)abstract
- CONTEXT: Information on how crop yields are affected by weather variations and extreme weather is needed to develop climate adaptation measures for arable cropping systems. Here, we analysed the effects of weather anomalies and soil texture on crop yield anomalies across Sweden from 1965 to 2020. OBJECTIVE: The aims of this study were to (i) assess the effects of temperature and precipitation anomalies and extreme weather on crop yield anomalies for major field crops across Sweden, (ii) quantify how crop responses to weather anomalies vary along the north-south climate gradient across Sweden, and (iii) elucidate the impacts of soil texture on yield responses to weather anomalies. METHODS: We used daily mean air temperature, daily total precipitation, soil texture and crop yield data from public databases covering all 21 counties in Sweden. Yield data was detrended to account for the effects of agricultural intensification on crop productivity. To assess seasonal weather influences on crop yields, temporal trends of daily average temperature and daily total precipitation were detrended for each season containing a three-month period. We also used a water balance index and a heat wave index to evaluate the impact of extreme weather. RESULTS AND CONCLUSIONS: Our analyses showed that years with extreme weather during summer (i.e. heat waves, drought or water excess) resulted in the largest negative yield anomalies. Spring-sown crops were more negatively affected by extreme weather compared to autumn-sown crops, which we associate with differences in the lengths of the growth period for autumn- and spring-sown crops. Effects of soil texture on yield anomalies were found for spring-sown cereals, where negative effects of drought were exacerbated with increasing sand content. Moreover, we showed that the effects of weather conditions on crop yield anomalies differed between different regions within the country. In northern Sweden, crop yields were more sensitive to excess water, while drought effects were more pronounced in southern Sweden. Similarly, increased summer temperatures favoured crop yields in northern Sweden but had a negative impact on crop yields in the southern part of the country. SIGNIFICANCE: Our study demonstrates that weather impacts on yields vary between crops and locations, and that adaptation to future climate will require crop- and site-specific strategies.
|
|
