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Site-specific nitrogen (N) management in precision agriculture is used to improve nitrogen use efficiency (NUE) at the field scale. The objective of this study has been (i) to better understand the relationship between data derived from an unmanned aerial vehicle (UAV) platform and the crop temporal and spatial variability in small fields of about 2 ha, and (ii) to increase knowledge on how such data can support variable application of N fertilizer in winter wheat (Triticum aestivum). Multi-spectral images acquired with a commercially available UAV platform and soil available mineral N content (Nmin) sampled in the field were used to evaluate the in-field variability of the N-status of the crop. A plot-based field experiment was designed to compare uniform standard rate (ST) to variable rate (VR) N application. Non-fertilized (NF) and N-rich (NR) plots were placed as positive and negative N-status references and were used to calculate various indicators related to NUE. The crop was monitored throughout the season to support three split fertilizations. The data of two growing seasons (2017/2018 and 2018/2019) were used to validate the sensitivity of spectral vegetation indices (SVI) suitable for the sensor used in relation to biomass and N-status traits. Grain yield was mostly in the expected range and inconsistently higher in VR compared to ST. In contrast, N fertilizer application was reduced in the VR treatments between 5 and 40% depending on the field heterogeneity. The study showed that the methods used provided a good base to implement variable rate fertilizer application in small to medium scale agricultural systems. In the majority of the case studies, NUE was improved around 10% by redistributing and reducing the amount of N fertilizer applied. However, the prediction of the N-mineralisation in the soil and related N-uptake by the plants remains to be better understood to further optimize in-season N-fertilization., Precision Agriculture, 22 (2), ISSN:1385-2256, ISSN:1573-1618

To develop precision agriculture (PA) to its full potential and make agriculture progress toward sustainability and resilience, appropriate criteria for the economic assessment are recognised as being one of the most significant issues requiring urgent and ongoing attention. In this work, we develop a web-tool supporting the assessment of the net economic benefits of integrating precision farming technologies in different contexts. The methodological approach of the tool is accessible to any agricultural stakeholder through a guided process that allows to evaluate and compare precision agriculture technologies with conventional systems, leading the final user to assess the financial viability and environmental impact resulting from the potential implementation of various precision agriculture technologies in his farm. The web-tool is designed to provide guidelines for farmers over their decisions to invest in selected PA technologies, by increasing the knowledge level about novel technologies characteristics and the related benefits. Possible input reduction also offers the possibility to investigate the mitigation of environmental impacts.

Soil carbon sequestration (SCS) is one of the cheapest and technically least demanding carbon dioxide (CO2) removal (CDR) or negative CO2 emission technologies. For a realistic assessment of SCS, it is critical to evaluate how much carbon (C) can be stored in soil organic matter under actual agricultural practices. This includes typical crop rotations and fertilization strategies, depends on resources that are available (e.g. farmyard manure (FYM)) and are affordable for farmers. Furthermore, it is important to assess SCS based on given climatic and soil conditions. Here, we evaluate changes in soil C storage for Switzerland using data from eleven long-term field experiments on cropland and permanent grassland that include common local practices. At all sites, changes in soil organic carbon (SOC) stocks were measured in topsoil (∼0-0.2 m) in response to a total of 80 different treatments including different types of mineral or organic fertilization (e.g. FYM, slurry, peat, compost) or soil management (tillage vs. no-till). The treatments were applied to different, diverse crop rotations or grass mixtures that are representative for Switzerland. We found that topsoils lost C at an average rate of 0.29 Mg C ha−1 yr−1, although many of the investigated treatments were expected to lead to SOC increases. Based on a linear mixed effects model we showed that SOC change rates (ΔSOC) were driven by C inputs to soil (harvest residues and organic fertilizer), soil cover and initial SOC stocks. The type of land use or soil tillage had no significant effect. Our analysis suggests that current efforts to manage soils sustainably need to be intensified and complemented with further techniques if Switzerland wants to achieve the goal of the 4 per 1000 initiative.

Traffic induced soil compaction, as well as the associated negative effects on soil structure and soil functions can be reduced by the use of permanent traffic lanes for all field vehicles – known as Controlled Traffic Farming (CTF). Adapted to the small-scale agriculture in Switzerland, a simplified version may be applicable. In the current study, we evaluated the implementation of a “CTF-light” system in the Swiss Central Plateau specifically for heavy machines used for crop protection, fertilisation and harvesting. During a three-year trial (2015–2017), we investigated the practicality of this “CTF-light” system by using standard machinery on 17 study sites. The effects of permanent lanes on soil penetration resistance, water infiltration rate, bulk density, macropore volume and yields were evaluated. Harmonising machine working widths was challenging and required intense planning, however, we were able to realise “CTF-light” on all sites. After three years of controlled trafficking, we observed developing differentiation of soil properties. In untrafficked areas, there was a tendency of decreased penetration resistance and bulk density as well as an increased infiltration rate and macropore volume. This significantly increased maize yield, which is very sensitive to soil compaction. For other field crops, no consistent yield differences have yet been determined. The technical and organisational effort to realise permanent traffic lanes for heavy standard machines is not to be underestimated.

Positive driving performance and ergonomic effects are ascribed to satellite-based automatic guidance systems. Although the literature had provided some information on working-width utilisation, turning-time requirement and steering accuracy, the relevant studies had mostly been carried out on smaller areas of land under experimental conditions. Little information was found on the nearly-always-mentioned reduction in driver workload. A large-scale field trial under practical conditions was carried out in the Czech Republic for the expanded clarification of the driving-performance and ergonomic effects of automatic guidance systems. Various parameters were recorded for 17 drivers with respect to primary tillage, seedbed preparation and sowing both with and without a guidance system. Working widths were between 5 and 15 m, and field sizes between 1.2 and 15.7 ha. The findings showed that driving speeds, turning times and working-width utilisation were in some cases more advantageous with a guidance system, but did not differ statistically significantly. The variations caused by driver, field shape and field margins had a greater influence than the use of guidance systems. Two parameters differed significantly, however. Guidance systems increased the average steering accuracy and delivered a lower heart rate. The study confirmed that guidance systems can deliver positive driving-performance effects and can contribute to driver relief.

A long-term tillage experiment in Tänikon, Switzerland showed that compared to ploughed plots, untilled plots developed a compact soil structure with decreased porosity and a trend towards lower oxygen concentration in the soil air. All these factors resulted in lower plant yields. To investigate the influence of wheeling on these plots, the shallow-tilled plots were converted to controlled traffic farming (CTF) with no-tillage in 2008. The hypothesis is that a sustainable improvement in soil structure and plant development is achievable in areas with no traffic. In a field trial with four repeated blocks, ‘CTF no-tillage’ was compared with ‘random trafficked mouldboard ploughing’ and ‘random trafficked no-tillage’. The crop rotation was winter wheat – winter barley – meadow, established on luvisol (23% clay, 34% silt, 42% sand) with an annual rainfall of 1190mm and an average annual temperature of 8.4 °C. An intensive monitoring programme was set up for various parameters: Soil-surface-level changes, penetration resistance, macropore volume, soil-air composition, matric potential, volumetric soil-water content, emergence rate, intermediate harvests and harvest yield. Results for 2008 to 2011 show that traffic has a clearly negative impact on soil structure in all variants, even when wheelings are done with low tyre-inflation pressure. Traffic-induced soil-surface-level changes were small, but nonetheless affected the soil’s physical parameters. Soil penetration resistance is higher and soil oxygen content after precipitations lower in the trafficked areas than in traffic-free zones. Yield effects were not as pronounced as in other published field trials. CTF and no-tillage achieved approximately the same yield levels, but routine ploughing resulted in the highest yields. CTF leads to a certain improvement in the soil structure, but the plant response showed that more improvement is necessary to optimise yields.

Soil tillage and its interaction with climate change are widely discussed as a measure fostering carbon sequestration. To determine possible carbon sinks in agriculture, it is necessary to study carbon sequestration potentials in relation to agricultural management. The aim of this paper is to evaluate the soil carbon sequestration potential of a site in north-eastern Switzerland under different tillage systems. The study was performed as a long-term (19-year) trial on an Orthic Luvisol (sandy loam) with a mean annual air temperature of 8.4 °C and a long-term precipitation mean of 1183 mm. The soil organic carbon (SOC) concentration was determined five times during the study period, with the paper focussing mainly on the year 2006. The main objective was to quantify the influence of mouldboard ploughing (PL), shallow tillage (ST), no-tillage (NT) practices, and grassland (GL) on soil organic carbon content, the latter's different fractions (labile, intermediate, and stable), and its distribution by depth. In calculating the SOC content of the whole soil profile, we included a correction factor accounting for variations in bulk density (equivalent soil mass). The total SOC stock at a depth of 0–40 cm was 65 Mg C ha −1 , and although higher under GL, did not differ significantly between PL, ST, and NT. SOC concentrations per soil layer were significantly greater for NT and ST (0–10 cm) than for PL, which had greater SOC concentrations than NT and ST at 20–30 cm depth. Both SOC concentrations and stocks (0–20 cm) were largest under GL. In all treatments, most of the carbon was found in the intermediate carbon fraction. There was no significant difference in any of the three SOC fractions between NT and ST, although there was between ST and PL. A sharp decrease in C-concentrations was observed in the first 7 years after the transition from grassland to arable land, with a new equilibrium of the carbon concentration in the 0–40 cm layer being reached 12 years later, with no significant difference between the tillage treatments. Overall, the results indicate that effects of tillage on soil carbon are small in moist, cold-temperate soils, challenging conversion into no-till as a measure for sequestering C.

How do different soil tillage systems influence soil quality over the years? Under moist cool conditions is it possible in the long term to reduce dramatically soil tillage intensity without experiencing reductions in yield or other problems? In 1987, the Swiss Federal Research Station for Agricultural Economics and Engineering in Tanikon initiated a long-term soil tillage trial to clarify these questions. The trial compared mouldboard plough, chisel, paraplow, shallow tillage and no-tillage systems on a well-drained Orthic Luvisol with 160 g kg −1 clay, 310 g kg −1 silt, and under a climate that has a mean annual precipitation of 1180 mm. The tillage treatment effects were evaluated by measuring several biological, chemical, and physical soil quality indicators. Reduced soil tillage increased earthworm populations, reduced Pseudocercosporella herpotrichoides infection in wheat ( Triticum aestivum ) and increased plant colonisation by arbuscular mycorrhizal fungi. Yields for no-tillage and other ploughless cultivation techniques were on par with those obtained by ploughing. An exception was direct-drilled maize ( Zea mays ), where no-tillage decreased yield by more than 10% over the course of 14 years. In the first 7 years of the trial, the level of soil organic carbon in all the tillage regimes was approximately 40% lower than natural grassland (initial situation 1987=75 Mg SOC ha −1 ). The no-tillage method did not differ from the others in respect of bulk density, but it showed an increased preconsolidation stress and hence better trafficability. Under Switzerland’s moist cool climatic conditions, it is possible to reduce soil tillage intensity without substantial reductions in yield, and at the same time improve soil quality.

Reduced tillage can change numerous physico-chemical properties of soil and the activity of various microorganisms including mycorrhizal and pathogenic soil fungi, and thus influence nutrient uptake by plant roots. We studied the colonization of roots by mycorrhizal and nonmycorrhizal fungi and nutrient concentrations in plant tops grown during a 3-yr rotation of maize (Zea mays L.), winter wheat (Triticum aestivum L.), and canola (Brassica napus L.) in two sites in Switzerland where fields have been under three tillage treatments (conventional, CT; chisel plow, CP; and no-tillage, NT) since 1987. Maize roots were colonized to a greater extent by mycorrhizal fungi with NT than with CP or CT treatments. Wheat roots were equally and weakly colonized by mycorrhizal fungi in all treatments but were relatively heavily (up to 35% of the root length) colonized by several nonmycorrhizal fungi such as Olpidium, Polymyxa, and Gaeumannomyces-Phialophora complex. Canola roots, as expected, were not colonized by any mycorrhizal fungi but were colonized by O. brassicae. Reduced tillage intensity altered the concentration of some nutrients in the leaves of mycorrhizal host plants (maize and wheat) but did not change those in nonhost canola. Changes in nutrient concentrations in maize and wheat leaves were likely due to the combined effects of colonization of their roots by various mycorrhizal and nonmycorrhizal fungi and not to some changes in the physical or chemical properties of soils. Cluster analysis showed that Mn concentration in wheat leaves was closely related to the Gaeumannomyces-Phialophora complex and concentrations of Ca, K, and Zn were related to tillage intensity and to the Polymyxa colonization of roots. We conclude that the colonization of roots by nonmycorrhizal root parasites, and especially by nonfilamentous obligate fungi, need to be taken into account in mycorrhizal studies conducted under field conditions.

In particular in organic cultivation, potato blight caused by the fungus phytophthora infestans can lead to significant yield, quality and storage losses. Protecting potatoes against this disease demands preventive measures, appropriate regulation strategies, and optimum spraying techniques. The latter involves an even distribution and deposition of the preventive copper contact fungicides on the stem and both sides of the leaves as well as a good penetration. Compared to conventional spraying, the newly developed underleaf spraying technique improved the coverage of the potato leaves and decreased phytophtora infection significantly.