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The purpose of this study was to investigate the impact of controlled traffic farming (CTF) with respect to soil physical properties and crop yield for Swedish conditions. Three field trials were conducted for six growing seasons in central and southern Sweden. In two of the trials, we compared CTF with random traffic farming (RTF) in deep chiseling (DC, 15–20 cm), shallow cultivation (SC, 5–10 cm) and no-till. The third trial was on farm study by using the existing CTF module at the farm. In the tracks of CTF (traffic zone) dry bulk density was increased and water movement was decreased. Soil penetration resistance was greater in the traffic zone than in the crop zone in some of the trials but the difference was not statistically significant. On average, crop yield was similar between CTF and RTF for all trials. Yield in the traffic zone was significantly less than that in the crop zone in the on-farm trial, but the yield in both zones were similar in the field trial at Lönnstorp, south Sweden. On the contrary, in the field trial at Säby 1 in Uppsala, central Sweden, crop zone produced less yield than traffic zone probably because of too loose soil, which impaired the uptake of nutrients and water. We conclude that if vehicle weight is not very high and the soil is not vulnerable to compaction, dual wheels and CTF are equal options. [ABSTRACT FROM AUTHOR]

Abstract: Soil disturbance by tillage and traffic often adversely affects aggregate stability, leading to colloid and particle mobilisation, which may result in crusting, low water infiltration rate and sediment transport. Hence, minimising soil tillage is an important step in conserving soil quality. This study investigated readily dispersible clay (RDC) and particle transport as affected by shallow tillage or mouldboard ploughing in five Swedish long-term reduced tillage experiments that had been underway for 15–31 years at the time of soil sampling. The soils of the experimental sites are Eutric and Dystric Cambisols. RDC of soil samples, collected in 0–10cm and 12–17cm depth, from mouldboard ploughed (MP) and shallow tillage (ST) plots was compared by measuring turbidity. Particle transport was also determined in undisturbed soil columns (20cm in diameter and 20cm high) from these treatments. RDC and particle transport were significantly lower for ST than for MP at three sites where clay content was above 30%. Particle transport in two soils (clay content above 40%) increased with irrigation events, indicating that preferential transport dominated in unsaturated soil columns, but matrix flow and, consequently, particle dispersion increased as the soil approached saturation. Despite more organic C accumulation in the upper 0–10cm of ST than in the 12–17cm soil layer, clay dispersion was lower in the latter. Particulate P (Total P−dissolved P) was well-correlated to turbidity, suggesting that analysis costs often can be cut by only measuring turbidity. Shallow tillage generally produced positive environmental effects without negative effects on crop yield, especially on soils with high clay content. [Copyright &y& Elsevier]

A Field experiment to investigate nutrient leaching was established in 2011 on a clay loam. The field site is located about 15 km south of Uppsala in eastern Sweden (59°43'0" N; 17°41'21" E). The experimental field is about 0.42 ha (72 × 50 m), with a slope in the north-south direction of about 1%. At the lower part of the field, grassed buffer strips were established as follows: A) Control, which is managed in the same way as the main field; B) Grass buffer strips; C) As B, but the grass harvested once a year. Each treatment was 6 m by 6 m, and is replicated in four blocks. Each plot is drained with a central 6-m long drain pipe at 1 m depth. The rest of the field is not drained. Surface runoff and drainage water are led to an automated measuring and sampling station. The samples were analyzed for phosphorus, nitrogen and organic carbon. On average, the leaching of particulate phosphorus via drainage tiles was reduced by 17 % in the grass buffer strips but the effect of harvesting the grass on reducing leaching was very little. Nitrate leaching was reduced by 28 %. Surface runoff was scarce during the experimental years and its data was insufficient to draw conclusions. [ABSTRACT FROM AUTHOR]

Seedbed preparation research in Sweden over the past 35 years is reviewed. In Swedish farming, spring sown small grains are the dominant crop, but their establishment is often problematic. The spring is thedriest season and this may cause poor crop emergence, particularly in clay and clay loam soils, where the seedbed often becomes coarse and non-uniform and dries out quickly. In silty soils, the major problem is surface layer hardening that hampers seedling emergence. Seedbedproblems have attracted considerable research interest. A method to characterize seedbed properties based on frame sampling is presented.A survey of seedbeds in farm fields showed that the water content attraditional spring sowing of small grains (as soon as the soils are dry enough for harrowing) is usually below wilting point to a depth of 3 cm in soils with >25% clay, but in coarse-textured soils, there is usually plant available water up to the soil surface. The function of seedbeds was investigated by establishing seedbeds with predetermined properties and sowing depths in shallow plastic boxes. Under dry weather conditions, good emergence of small grain crops could always be achieved without irrigation, provided the seed was placed directlyonto a firm seedbed base with a water content at least 0.05 g g-1 greater than that at a matric tension of 1500 kPa and was covered by a 4 cm deep seedbed with >50% aggregates <5 mm. The risk of poor emergence due to surface layer hardening depended much more on the sowing depth than on the aggregate sizes of the seedbed. Several series of field trials are also summarized. In trials on silty soils, a fine seedbed increased both number of plants and crop yield by 5% as compared to a coarse seedbed. In clay and clay loam soils, natural factors, particularly previous freezing and thawing, affected seedbedcharacteristics more than the choice of harrows and their adjustmentor the number of harrowings. In most soils, rolling after sowing improved f [ABSTRACT FROM AUTHOR]

Abstract: Soil tillage has the potential to influence water flow and solute transport through the soil by cutting continuous macropores which connect the soil surface to the subsoil. Tillage also affects soil organic carbon sequestration which may lead to different sorption and degradation properties depending on the long-term tillage practices. The objective of this study was to quantify the differences in sorption, degradation and leaching of the herbicides bentazone and isoproturon between conventional tillage (CT) and reduced tillage (RT) under Swedish conditions. Three sites, Ultuna (silty clay), Säby (loam), and Lönnstorp (sandy loam moraine till), where replicate plots had been under either CT or RT for at least 9 years, were included in the study. A higher organic carbon content had developed in the top 5cm of RT plots compared to the 10–20cm depth and CT plots since the establishment of the experimental treatments. Adsorption and degradation were studied in laboratory experiments and solute transport was studied in undisturbed column experiments using non-reactive tracers and herbicides. The results from the column experiments were not significantly different between tillage treatments for Säby and Lönnstorp. For Ultuna, RT resulted in a more pronounced preferential tracer transport pattern and isoproturon leaching was twelve times larger compared to CT columns. This indicates that the tillage treatment had affected the macropore connectivity only at Ultuna. Freundlich adsorption coefficients for both bentazone and isoproturon were larger (though not always significantly) in the top 5cm of RT soil compared to the 10–20cm depth and to CT, reflecting the higher organic carbon content. The degradation rate was also generally larger (though not always significantly) in the top 5cm of RT soil. These results show that RT has the potential to reduce pesticide leaching. However, any such reduction may be counter-balanced by enhanced preferential flow for soils where RT results in improved macropore connectivity. [Copyright &y& Elsevier]