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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]

Two field experiments with drained plots on clay soils (60% and 25% clay) demonstrated a significant reduction in leaching of total phosphorus after application of structure lime. Aggregate stability was significantly improved. Phosphorus leaching in particulate form was significantly reduced following structure liming at the site with a very high clay content. Sites representing low (50 mg kg−1) and high (140 mg kg−1) levels of phosphorus extractable with acid ammonium lactate in topsoil displayed differing effects on leaching of dissolved reactive P (DRP). This form of phosphorus was only significantly reduced compared with the control at one site with high topsoil phosphorus status and relatively high (17–18%) degree of phosphorus saturation in the subsoil. Laboratory experiments with simulated rain events applied to topsoil lysimeters from the same site also demonstrated a significant reduction in leaching of DRP. These findings indicate that structure liming is an appropriate leaching mitigation measure on soils with both a high clay content and high soil phosphorus status. [ABSTRACT FROM AUTHOR]

Highlights: [•] More than 1000 experimental years were included in the analysis of yield data. [•] Crop yield on average 10% lower for no-tillage compared to mouldboard ploughing. [•] Crop yield on average 2% lower for shallow tillage compared to mouldboard ploughing. [•] Dicots were more sensitive to compaction than cereals. [•] Winter wheat yield in reduced tillage was much affected by preceding crop. [ABSTRACT FROM AUTHOR]

Phosphorus (P) leaching from agricultural soils is a serious environmental concern. Application of aluminium water treatment residuals (Al-WTR5) at a rate of 20 Mg ha-1 to clay soils from central Sweden significantly increased mean topsoil P sorption index (PSI) from 4.6 to 5.5 imol kg-1 soil. Mean degree of P saturation in ammonium lactate extract (DPS-AL) significantly decreased from 17 to 13%, as did plant-available P (P-AL). Concentrations of dissolved reactive P (DRP) decreased by 10-85% in leaching water with Al-WTR treatments after exposure of topsoil lysimeters to simulated rain. Soil aggregate stability (AgS) for 15 test soils rarely improved. Three soils (clay loam, silty loam and loam sand) were tested in greenhouse pot experiments. Aluminium-WTR application of 15 or 30 ton ha-1 to loam sand and a clay loam with P-AL values of 80-100mg kg-1 soil significantly increased growth of Italian ryegrass when fertilised with P but did not significantly affect growth of spring barley on any soil. Al-WVR should only be applied to soils with high P fertility where improved crop production is not required. [ABSTRACT FROM AUTHOR]

Abstract: Concentrations of dissolved reactive phosphorus (CDRP) and particle-bound phosphorus (CPP) were investigated in soil columns taken from different parts of three selected agricultural fields. The columns (mini-lysimeters 20cm in diameter, 20cm high) were exposed to on average 64±6mm of simulated rainfall. Total phosphorus concentrations (CTP) in water percolating from the lysimeters were similar to the CTP observed in drainage water leaving the fields, but the CDRP/CTP ratio was significantly (p <0.001) higher in the percolate. The high CDRP (up to 0.4mgL−1) measured in the percolate may have partly derived from decomposition of accumulated senescing vegetation and litter material, since CDRP in percolating water was related to total organic carbon concentration (TOC) in the shallow topsoil (0–5cm) and to phosphorus concentration in soil extract of ammonium lactate (P-AL) from the same soil layer. Another easily identified factor clearly related to CDRP in percolate from the lysimeters was the degree of phosphorus saturation (DPS) in the same soil P-AL extract. The factors giving best prediction of CPP and leaching were the amount of percolate passing through the soil columns and total phosphorus concentration in the topsoil determined after oxidation with nitric acid (TP-HNO3). One field under grass ley, including the slope and depression close to the field outlet, comprised 24% of total field area. In the other two fields these areas (11 and 17% of total area respectively) were under long-term permanent green fallow as an internal buffer zone (IBZ). The lysimeter studies indicated that these areas had a higher risk of DRP losses than the rest of the fields. In addition, the P content of the particles in water from the depression was unusually high. Aggregate stability, measured indirectly as readily dispersible clay and expressed as nephelometric turbidity units (NTU), was significantly stronger at the lowest point of one IBZ (27–35NTU) than in stubbled parts of the same field (62NTU), and the turbidity of water percolating through the topsoil was lower (5–27NTU). [Copyright &y& Elsevier]

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]

• Liming effects on structural stability and dissolved reactive phosphorus in subsoil were examined. • Similar effects on structural stability were found for the lime types CaCO 3 and CaO. • Clay dispersion decreased linearly by 17 % up to pH 8.4. • Soil aggregate stability and P solubility increased to a peak at pH 7.5–7.8. • At pH 8.4, wet aggregate stability and P solubility declined to levels seen at pH 7. A 22-month incubation experiment was conducted to study the effect of lime on clay dispersion, wet aggregate stability (WAS) and dissolved reactive phosphorus (DRP), using a heavy clay subsoil with an initial pH of 7.0 and 7.3 g kg−1 of soil organic carbon. Lime was applied to achieve soil pH values of 7.5, 8 and 8.4. Clay dispersion decreased linearly with increased pH (corresponding to an increase in lime amount) for both lime types (R2 = 0.44 for CaO; R2 = 0.53 for CaCO 3 , P < 0.05), with a decrease of 2–16 % (CaO) and 3–17 % (CaCO 3) compared with the control. Both WAS and DRP followed piece-wise linear functions, with an increase and peak around pH 7.5–7.8, and a decline at higher pH (WAS: R2 = 0.73 for CaO, R2 = 0.68 for CaCO 3 , P < 0.001; DRP: R2 = 0.84 for CaCO 3 , R2 = 0.33 for CaO, P < 0.001). Wet aggregate stability increased on average by 13 % and 11 % at the lowest and intermediate levels, respectively, compared with the control. At the highest lime application rate, WAS was 6 % (CaO) and 8 % (CaCO 3) lower than in the control. These differences were probably caused by changes in electrical charge and in concentrations of soluble calcium and dissolved organic carbon (DOC) as the pH increased. More studies are needed to understand the processes in detail and to draw conclusions that are more robust. [ABSTRACT FROM AUTHOR]

The main objective of the present study was to evaluate different injection methods for slurry to ley on three different soils. A further objective was to study the effect of soil moisture on the working depth of an injector and on the slurry infiltration rate. In full-scale experiments, the placement of slurry, ammonia emissions and yield were measured after injection with three techniques: pressurised injection, shallow injection with V-shaped discs, and shallow injection with two angled discs. In an adjacent experiment the effect of soil moisture was studied. The performance varied between the injectors and only the injector with angled discs was able to place the slurry in ley below the soil surface on all soils studied. The ammonia release was on average halved after injection with angled discs compared with band spreading, giving a mean ammonia loss of 39% of the total ammoniacal nitrogen (TAN) applied. Despite the reduction in ammonia losses with the angled disc injector, this did not result in higher dry matter yield or higher nitrogen efficiency of the second cut compared with band spreading. The working depth of a slurry injector increased significantly with increasing soil water 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]

It has been suggested that liming can improve soil structure and thereby decrease losses of particles and associated nutrients. In this study, two types of structure lime, slaked lime (Ca(OH)2) and a mixed product of calcium carbonate (CaCO3) and slaked lime (Ca(OH)2), were applied at three different rates in field trials on clayey soils (23%–40% clay). A combination of primary tillage and structure liming was also studied, in a split-plot trial on a clayey soil (25% clay). Aggregate (2–5 mm) stability, measured as reduction in turbidity (which is strongly correlated with losses of particulate phosphorus), was significantly increased with the highest application rates of both structure lime products. Aggregate size distribution was also improved with structure lime, creating a finer tilth in the seedbed. Yield response to structure lime was not consistent, with both negative and positive responses over the four-year study period. Positive yield responses can possibly be attributed to the finer tilth preventing evaporation in two dry growing seasons. Negative yield responses were probably an effect of impaired phosphorus availability associated with limited precipitation in May-July in 2011 and 2013. Two years after liming, soil pH levels were significantly elevated in plots with the highest application rate of structure lime, whereas no significant increases were found three years after liming. However, a lingering effect of liming was still detectable, as manganese concentration in barley grain was significantly lower in plots with the highest application rates of both structure lime products in the fourth study year. These results indicate that structure liming can be used as a measure to mitigate phosphorus losses from clayey soils, thereby preventing eutrophication of nearby waters. However, the yield response was varying and unpredictable and thus further investigations are needed to determine the circumstances in which field liming can act efficiently not only to prevent phosphorus losses, but also to ensure consistent yield increases. [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]

Highlights: [•] Structural liming reduced PP leaching for at least six years. [•] Large spatial variation in P losses but moderate variation in soil P and discharge. [•] Broadcasting or placement of fertiliser P had no clear effect on P leaching. [•] Shallow autumn tillage provided no significant benefits for water quality. [•] Replacing arable land with unfertilised fallow did not reduce P leaching losses. [Copyright &y& Elsevier]

Overall, arable soils in Sweden are currently generally close to phosphorus (P) balance, but excessive P accumulation has occurred on animal fur farms, i.e., those rearing mink ( Mustela vison) and foxes ( Alopex lagopus and Vulpes vulpes). Manure P from these farms has sometimes regarded as sparingly soluble. Laboratory lysimeter topsoil trials with simulated rain demonstrated that potential leaching of P in dissolved reactive form (DRP) can be very high, even for heavy clay (50%-65%) soils. The Swedish/Norwegian soil test P-AL (soil P extracted with acid NH4 lactate, AL) proved useful as a potential indicator of DRP leaching risk (regression coefficient [ R2] = 0.89) from fur farms. The upper 5-cm soil layer, with 190% higher (median) soil P status than the 5-20 cm layer, was the major source of potential DRP leaching through soil columns at the site, despite having been under grass or green fallow for the past 8 y. In percolate from topsoil lysimeters, DRP concentration increased by 0.29 mg L-1 after the long-term manure application but only by 0.14 mg L-1 after the single slurry application when compared to no addition of slurry. Therefore, the build-up to a high soil P status due to the long-term application of mink manure was more important than a single application of pig slurry at a rate corresponding to 22 kg P ha-1 with respect to soil leachate DRP losses in this lysimeter study. The study stresses the importance of precision farming, in which the amount of slurry-P applied is based on testing the already existing soil P content. [ABSTRACT FROM AUTHOR]

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 albaL., oilseed rape,Brassica rapaL., Metzg., sugar beet,Beta vulgarisL. and red clover,Trifolium pratenseL.) 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 pratenseL.) 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. [ABSTRACT FROM PUBLISHER]

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]

• Structure liming modified macropore networks, but not mesopore networks. • Structure lime tended to reduce macroporosity, macropore diameters and connectivity. • Structure liming tended to reduce readily dispersible soil. • Liming effects on pore networks differed substantially between sites. • Although quantitatively different, effects generally pointed in the same direction. Structure liming aims to improve soil structure (i.e., the spatial arrangement of particles and pores) and its stability against external and internal forces. Effects of lime application on soil structure have received considerable interest, but only a few studies have investigated effects on macro- and mesopore networks. We used X-ray computed tomography to image macropore networks (ø ≥ 0.3 mm) in soil columns and mesopores (ø ≥ 0.01 mm) in soil aggregates from three field sites with (silty) clay soils after the application of structure lime (3.1 t ha−1 or 5 t ha−1 of CaO equivalent). Segmented X-ray images were used to quantify soil porosity and pore size distributions as well as to analyse pore architecture and connectivity metrics. In addition, we investigated the amount of readily dispersible soil particles. Our results demonstrate that structure liming affected both, macropore networks and amounts of readily dispersible soil to different degrees, depending on the field site. Significant changes in macropore networks and amounts of readily dispersible soil after lime application were found for one of the three field sites, while only some indications for similar changes were observed at the other two sites. Overall, structure liming tended to decrease soil macroporosity and shift pore size distribution from larger (ε >1.0 mm) and medium sized macropores (ε 0.3–1.0 mm) towards smaller macropores (ε 0.1–0.3 mm). Furthermore, liming tended to decrease the critical and average pore diameters, while increasing the surface fractal dimension and specific surface area of macropore network. Structure liming also reduced the amounts of readily dispersible soil particles. We did not find any changes in mesopore network properties within soil aggregates or biopore networks in columns and aggregates. The effects of lime on macropore networks remain elusive, but may be caused by the formation of hydrate phases and carbonates which occupy pore space. [ABSTRACT FROM AUTHOR]

This is the first in a series of papers describing the impact of two decades of no-till in the Oberacker long-term field experiment in Switzerland. The experiment was established in 1994 on a sandy loam and compares two tillage systems, conventional tillage with mouldboard ploughing (MP) and no-till (NT). Crops are grown in a six-year rotation, namely peas ( Pisum sativum L.) − winter wheat ( Triticum aestivum L.) − field beans ( Phaseolus vulgaris L.) − winter barley ( Hordeum vulgare L.) − sugar beet ( Beta vulgaris L.) − silage maize ( Zea mays L.). This study investigated the impact of the two tillage systems on (i) nutrient distribution and storage in the soil profile, (ii) the depth distribution of soil organic carbon and (iii) crop productivity. Soil samples were collected layer-by-layer following cultivation layers and natural soil horizons in a metal frame (0.5 m × 0.5 m cross-sectional area) down to 0.5 m depth. The layer boundaries were approximately 0.02, 0.05, 0.15, 0.25, 0.30, 0.40, and 0.50 m for NT, and 0.15, 0.25, 0.30, 0.40, and 0.50 m for MP. Soil organic carbon (SOC), total nitrogen (TotN), phosphorus (P), calcium (Ca), potassium (K), magnesium (Mg), pH, and bulk density were measured for each layer. The nutrient distribution was rather uniform within the plough layer in MP. In NT, there was strong stratification, with higher nutrient concentrations in the upper layers for TotN, K and Mg. This was associated with crop residue retention on the surface and reduced plant uptake due to low pH. In contrast, the distribution of P and Ca in NT was rather uniform in the 0–30 cm layer, with a trend towards maximum concentrations at around 20 cm depth. Total storage of nutrients per ha in the whole soil profile was similar in NT and MP for all nutrients. SOC stocks did not differ between NT and MP, although the depth distribution of SOC concentration was significantly different. The long-term average crop yield was slightly higher in NT than in MP, but the difference was not significant. Crop yield was significantly higher in NT for winter cereals (winter wheat, winter barley) and legumes (field beans and peas), but lower for root and tuber crops (sugar beet, potatoes). It can be assumed that the high crop yields in NT in the Oberacker long-term field experiment are due to the well-balanced crop rotation. [ABSTRACT FROM AUTHOR]

Losses of commonly used chemical pesticides from agricultural land may cause serious problems in recipient waters in a similar way to phosphorus (P). Due to analytical challenges concerning determination of glyphosate (Gly), transport behaviour of this widely used herbicide is still not well known. The objective of the present study was to quantify and evaluate leaching of Gly in parallel with P. Leaching losses of autumn-applied Gly (1.06 kg ha−1) via drainage water were examined by flow-proportional sampling of discharge from 20 drained plots in a field experiment in eastern Sweden. Samples were analysed for Gly in particulate-bound (PGly) and dissolved (DGly) form. The first 10 mm water discharge contained no detectable Gly, but the following 70 mm had total Gly (TotGly) concentrations of up to 6 µg L−1, with 62% occurring as PGly. On average, 0.7 g TotGly ha−1 was leached from conventionally ploughed plots, compared with 1.7 g TotGly ha−1 from shallow-tilled plots (cultivator to 12 cm working depth). Higher Gly losses occurred in snowmelt periods in spring, but then with the majority (60%) as DGly. All autumn concentrations of PGly in drainage water were significantly correlated (p<0.001) to the concentrations of particulate-bound phosphorus (PP) lost from the different plots (Pearson correlation coefficient 0.84), while PP concentrations were in turn significantly correlated to water turbidity (Pearson correlation coefficient 0.81). Leaching losses of TotGly were significantly lower (by 1.3 g ha−1; p<0.01) from plots that had been structure-limed three years previously and ploughed thereafter than from shallow-tilled plots. Turbidity and PP concentration also tended to be lowest in discharge from structure-limed plots and highest from shallow-tilled plots. This difference in TotGly leaching between soil management regimes could not be explained by differences in measured pH in drainage water or amount of discharge. However, previously structure-limed plots had significantly better aggregate stability, measured as readily dispersed clay (RDC), than unlimited plots. The effects of building up good soil structure, with strong soil aggregates and an appropriate pore system in the topsoil, on mitigating Gly and P losses in particulate and dissolved form should be further investigated. [ABSTRACT FROM PUBLISHER]