Differences in the type of production can have a significant implication for the use of CTF at its early development stage, at least. However, in the survey it was not specified on what types of production respondents apply CTF systems. In Table 3 results from a mean equality test for farm size between the CTF-user and non-user groups are presented. There is a significant difference in mean farm size between the two groups. The average farm area for the aggregate sample was 428 ha. CTF users operated significantly larger average farm area compared to 192 ha for Non-users . The farm numbers were too small to show statistical differences at a country level. About 77% of respondents reported that they were concerned about heavy machinery and its potential damage both on the field headlands and the main body of the field. Measures, other than direct adoption of CTF, being used by survey respondents to minimize traffic damage are presented in Table 4. Values in parenthesis are percentages relating to the CTF user only sub-sample. For the overall sample, the traffic damage minimization practices most used are: low ground pressure tyres on tractors and harvesters ; ploughing and sowing headlands last to reduce damage and; restricting grain trailers to field headlands for loading . The use of low-ground pressure tyres on tractors and harvesters is the most in use both in the overall sample and the CTF-user sub-sample. Deliberately fixing tramlines to minimize soil damage is moderately used when assessed for the total sample, but the second most used practice for CTF users. On the other hand, changing field turning headland to different parts and the use of dedicated crop transfer trailers fitted with large tyres are the least used.
When future adoption was considered, vertical rack system selection of smaller machines , selection of trailed equipment to reduce axle load and fixing tramlines are ranked highest. Half of the respondents use a combination of three or four of the nine damage minimization techniques listed in Table 4. CTF-users seem to use a combination of more techniques to minimize traffic-induced damage on their soil compared to the ’Non-users’ group where about 34% of the CTF-users and 23% of non-users apply a combination of five or more of the damage minimization techniques. Regarding crop establishment system, CTF-users employed reduced/ strip-tillage and no-till whereas the majority of Non-users practiced plough-based cultivation. There are wide differences in sample size, mean farm size and CTFuser proportion across countries included in the survey. Coupled with the sampling concerns of non-random selection, heterogeneity in sampling across countries, low survey response rate, and likely subjective/ perceptional differences in defining CTF, this makes it difficult to make cross country comparisons and/or generalizations at country level. As the available literature eliciting real experiences and perceptions of farmers is limited, the work reported here contributes to the development of this area of research.This is in line with the evidence that soil compaction is a threat to European agriculture . As shown in Table 4, farmers are employing a combination of techniques to minimize damage. CTF-users seem to use a greater number of damage minimization techniques in combination, probably because this group are acutely aware of compaction issues and open to adopting a multitude of measures. Among a list of techniques presented in Table 4, low-ground pressure tyres are the most used traffic damage minimization technique. Low ground pressure tyres have been recognized to improve topsoil conditions and crop yield . The technique is also the most in use by the CTF-user group. There can be several possible explanations for this. CTF has evolved from an approach where the pathways did not grow harvestable crop and where track widths were fixed, to a more flexible system where the base machine pathways are cropped, where some machine types have different track widths, and where varying machine weights require different tyre widths.
Consequently an approach where tyres and ground pressures are chosen to limit soil stress on traffic paths and field headlands is sensible. It is also possible that many who consider themselves as CTF-users but only limit or control traffic to a limited extent, also use low pressure tyres to limit damage generally. Overall, farmers that are most conscious of potential soil damage use a combination of techniques to protect the soil. CTF is used on larger farms with the CTF-user group on average operating nearly 5 times more area as the non-user group This may be a response to the need to reduce the damage risk of the heavier equipment on these farms coupled with the capacity of large farms to take advantage of economies of scale in machinery investment by amortizing fixed cost. This capacity to avail of scale benefits has been documented in previous studies including other PF technologies . In the current study, this is highlighted in the UK data where farm sizes are greater and CTF adoption is more common. The large mean farm size in UK is also docuemnted in Loughrey et al. . There are differences in the level of use of the system among the farmers who considered themselves as CTF-users, indicated by the proportion of farm area on which CTF is used. Most ‘CTF-users’ are not implementing a complete version of CTF as only 19% use the same pathways for all operations, and 56% use the same tracks/pathways for most crops and most machines. This has partly to do with subjectivities in definition of ‘CTF-user’ as described in the methods section. Partial adoption is to be expected as conversion to CTF demands several adjustments and learning through experimenting . Being conscious of the challenges of matching machine, track and tyre widths, and enabling deeper cultivation occasionally in full CTF systems, some farmers may still desire to manage their traffic by implementing some level of CTF as part of a soil management system that also includes reducing ground pressure and other soil protection measures. An important learning is that the current market for CTF rental/ contractor service appears to be very limited as most of the surveyed farmers practice CTF by their own. This could be because the technology and particularly its utility in terms of ’pay back’ is not fully proven across a range of real farm situations. Responses to open-ended questions about CTF challenges/disadvantages testify farmers’ challenges with contracting. Surveyed farmers have positive perceptions about the technical potential of CTF.
A considerable proportion of farmers who do not consider themselves as CTF-users said they would recommend other farmers to use CTF . This implies that implementation issues play a key role in adoption decisions. Overall, surveyed farmers had positive expectations about the benefits arising from using PF and CTF. Expectations about CTF adoption impact on long-term- gross margin were also optimistic. These expectations are supported by research on the effect of CTF adoption on crop yield and profit . Most of the surveyed farmers reported efficiency gains in machinery operating time due to CTF adoption. Optimistic expectations about labor saving and environmental benefits from using GNSS and PF were also expressed. There is already evidence of environmental benefits arising from practicing CTF in the form of reduced soil emissions . The long-term labor saving expectation is also supported by Luhaib et al. . The main issues farmers identified in this research regarding CTF were: affordability, compatibility; lack of decision support tools; adaptability ; and accessibility . Machinery cost is referred to as a pressing issue limiting farmers from taking advantage of CTF systems. This issue was also identified as a major constraint inAustralia . Perceptions that CTF is not suited for small farms are holding back European farmers from taking advantage of the technology, as was similarly noted by Larocque for western Canadian farmers. Examples from farmers’ responses to the open-ended questions about CTF challenges/disadvantages such as “cost of matching equipment”, “cost of machine renewal”, “cost of operations”, “big investments to get everything on the same track and working width, ”too expensive”, etc. exemplify the seriousness of the issue. Future availability of optimized turning paths and optimized field pathways to be implemented via auto-steer systems, in combination with low ground pressure and partially controlled traffic on headlands may be an alternative particularly for smaller farms. From the responses relating to the adoption of traffic damage limitation measures, traffic management measures that combine elements of CTF with other soil protection measures may have a role on many farms. If autonomous vehicles develop and take out the need for labour, machines may get smaller and their traffic issues would be more easily resolved with lower pressure tyres. Farmers in this study also emphasized the need for adaptable/flexible/simple machinery, compatibility among products from different suppliers, evidence of the utility of CTF systems under local conditions, decision support tools, and affordable purchase and modification solutions. Soil nematodes are of particular interest in soil food webs as they are the most abundant group of multicellular organisms in the soil . They occupy several trophic levels in the soil food web and can be classified into herbivores , bacterivores, fungivores, omnivores and predators . Additionally, they form complex networks with other soil biota, and play a crucial role in decomposition of soil organic matter, mineralization of plant nutrients and nutrient cycling . For instance, mobile grow rack nematodes regulate soil microbial communities and enhance microbial colonization through grazing on soil microbes . Being predators and prey, nematodes also provide information about the abundance and activity of other soil organisms, and thus have been used as indicators to study soil food web conditions , soil biodiversity and ecosystem functioning . Vegetable farming has become a major source of income for farmers worldwide.
Globally, vegetable fields account for approximately 7% of the total croplands, and this percentage is usually higher in developed countries . Compared to crop fields, vegetable fields are characterized by higher N application rates, more intensive production and management practices such as frequent irrigation and tillage as well as multiple planting-harvest cycles during the year . For example, fertilizer inputs in vegetable production were up to 600 kg N * ha− 1 *yr− 1 in comparison to 300 kg/ha of nitrogen per year in cereal cropping systems . Intensive agriculture has been shown to reduce soil biodiversity , which is of utmost importance for ecosystem functioning . Therefore, it is important to investigate how intensive farming practices may affect soil nematode communities. Organic farming systems are typically thought to be more sustainable than conventional systems , and organically managed farmlands have been growing to approximately 4.4 × 107 ha worldwide and are expected to increase further . This increasing trend is also true for organic vegetable farming in the Switzerland. Two global meta-analyses have shown that organic farming has a positive effect on soil biota , whereas a comprehensive understanding about whether and how organic management influences soil nematode community structure and associated functions is still lacking. Although the effects of organic farming on soil nematode have been assessed in grasslands , arable fields and vegetable fields , most studies are based on field experiments under homogeneous soil conditions at one particular location . The effect of organic farming on soil nematodes may vary with soil texture,crop species and land-use history . Thus, the effects of organic farming on soil nematode community may be dependent upon spatial scale because nematode abundance and community composition can be related to edaphic and climatic variations across scales . Finally, previous studies assessing the effect of organic farming on soil nematodes often focused on single vegetable types such as tomato , green peppers , and asparagus , and the comparative effect of organic farming on soil nematode communities across different vegetable types is largely unknown. Given the critical role of soil nematode in ecosystem functioning combined with increasing demands for organic vegetables, it is necessary to compare multiple field sites to obtain a robust assessment and a general understanding of how organic vegetable farming system influences soil nematodes. The wide-scale adoption of organic farming in Switzerland, particularly the Canton of Zurich with the second most licensees for organic products in 2020, provides a unique opportunity to elucidate how soil nematode communities and associated ecological processes respond to organic farming compared to conventional farming at a larger spatial scale.