Action: Reduce tillage
- A total of 42 individual studies (including seven replicated, controlled and randomized studies and six reviews) from Belgium, Denmark, France, Germany, Hungary, Ireland, Lithuania, the Netherlands, Slovakia, Switzerland and the UK investigated the effects of reducing tillage on farmland wildlife. Thirty-four studies (of which 21 were replicated and controlled and seven also randomized, and five reviews) from nine European countries found some positive effects on earthworms, some invertebrates (other than earthworms), weeds or farmland birds, of reducing tillage compared to conventional management. Positive effects included increased biomass, species richness or abundance of earthworms, greater abundance of some invertebrates other than earthworms, increased numbers of some weeds and/or weed species, higher Eurasian skylark nest density, earlier laying date and shorter foraging distances on reduced tillage fields, and greater abundance of some birds - including Eurasian skylark, seed-eating songbirds and gamebirds in late winter on non-inversion or conservation tillage. A review found tillage had negative effects on invertebrate numbers and no-till systems had more invertebrate bird food resources.
- Twenty-six studies (of which 13 replicated and controlled and three also randomized, and five reviews) from nine European countries found reducing tillage had either negative, no effect or no consistent effects on abundance, biomass, or species richness of some invertebrates (other than earthworms), earthworm abundance, biomass, or species richness, number of different plant species found as seeds, number of some weed species, mammal abundance, some bird species, and one study found bird preferences for conservation tillage fields decreased over time. Two studies found that crop type affected the number of weeds under different tillage regimes.
- One small replicated trial in the UK compared bird numbers under two different forms of reduced tillage, and found more birds from species that make up the ‘Farmland Bird Index’ on broadcast than non-inversion tillage fields.
- Two studies looked at the long-term effects of reduced tillage on earthworms (after ten years). One study found higher earthworm biomass under reduced tillage, the other study found earthworm abundance was the same between conventional and reduced tillage plots.
- Three of the studies mentioned above did not distinguish between the effects of reducing tillage and reduced pesticide and/or fertilizer inputs.
Conventional ploughing uses a mould-board plough, cultivating to a depth of around 20 cm. This intervention includes various methods to reduce the depth or intensity of ploughing, such as layered cultivation, non-inversion tillage and conservation tillage. It also includes stopping tillage altogether in some areas.
Reduced tillage is often used in the context of ‘Integrated Farm Management’ (IFM), a whole farm system designed to enhance natural processes within a productive system (for example Hasken & Poehling 1995). These studies have not been included here unless the effects can clearly be related to the tillage practice as opposed to other elements of the system such as crop rotation, field margins, or reduced chemical use.
Conservation tillage, often accompanied by the use of cover crops or retention of crop residues, is widely practiced in the USA. A 2004 review (Holland 2004) of the broad environmental effects of conservation tillage found the bulk of the evidence came from North American studies, with studies from Europe being sparse. For example, seven American studies found more ground-nesting birds on conservation tillage fields than conventionally tilled fields, and two studies found that rodents were more abundant in conservation tillage fields. However, both bird and rodent faunas in North America are functionally different from those in Europe (more ground-nesting birds in arable fields in the US, for example).
A set of studies on the effects of avoiding tillage when re-seeding heathland with grass to improve it for grazing (Grant 1992a-c) is included under ‘Employ areas of semi-natural habitat for rough grazing’.
Grant M. C. (1992a) The effects of re-seeding heathland on breeding whimbrel Numenius phaeopus in Shetland. I. Nest distributions. Journal of Applied Ecology, 29, 501-508.
Grant M. C., Chambers R. E. & Evans P. R. (1992b) The effects of re-seeding heathland on breeding whimbrel Numenius phaeopus in Shetland. II. Habitat use by adults during the pre-laying period. Journal of Applied Ecology, 29, 509-515.
Supporting evidence from individual studies
A replicated, controlled study of arable fields at eight sites in England (Edwards 1975) found that abundance of mites (Acari), springtails (Collembola) and some earthworm (Lumbricidae) species tended to be higher in direct-drilled plots, whereas insects were more numerous in ploughed plots. Direct-drilled plots contained 922-2,665 mites and 106-2,408 springtails, whereas ploughed plots contained 620-2,340 and 77-1,904 respectively. The opposite trend was seen for insects (direct-drilled: 39-123; ploughed: 44-156) as numbers of taxa such as fly (Diptera) larvae, rove beetles (Staphylinidae) and ground beetles (Carabidae) were higher in ploughed plots. Earthworm numbers were higher in direct-drilled at all sites (811-1,638 vs 628-1,243). Species such as the earthworm Lumbricus terrestris followed this trend (direct: 22-323; ploughed: 4-103), however, other species showed a slight tendency for a higher abundance in ploughed plots. Four replicate plots (6.4 x 18 m) of winter wheat under each treatment were established at Rothamsted Experimental Station (1964-1967) and Woburn (1965-1971). Half of each plot received insecticides. Soil arthropods were sampled every two months by taking soil cores, and earthworms in spring and autumn. In 1974 soil animals were assessed in six additional experiments comparing direct-drilling and ploughing by the Letcombe Laboratory and National Institute of Agricultural Engineering. Results for pest species are not presented here. This study is partly the same study as (Edwards & Lofty 1982).
A replicated controlled trial in southern England from 1973 to 1976 (Barnes & Ellis 1979) found there were always significantly more earthworms (Lumbricidae)/m2 on the direct-drilled (no-tillage) plots than on the ploughed plots. Numbers on tine-cultivated plots were similar to those on ploughed plots. For example, at one site, there were 145-345 earthworms/m2 in direct drilled plots (1973-1976), compared to 128-139 earthworms/m2 in tine cultivated plots (1973 only) and 50-218 earthworms/m2 in ploughed plots. There were no significant differences in numbers of particular earthworm species between the treatments. Deep-burrowing species were less than 10% of the earthworm communities in this study. Three cultivation treatments were compared in cereal fields (barley or winter wheat): direct drilling (no-tillage), tine cultivation to 8 or 15 cm, conventional ploughing to 20 cm. There were four replicates of each treatment at two separate sites, and for two soil types, clay and sandy loam.
A replicated trial on an experimental farm in eastern Scotland (Gerard & Hay 1979) found that the average number and biomass of earthworms (Lumbricidae) was significantly higher in untilled soil (137 earthworms/m2 and 0.9 tonnes earthworm/ha) than in cultivated treatments (67-93 earthworms/m2 and 0.3-0.4 tonnes/ha). The experiment was replicated eight times. Spring barley crops were managed from 1967 until 1973 with either deep ploughing (30-35 cm), normal ploughing (15-20 cm), tined cultivation (12-30 cm deep) or no ploughing (untilled, direct drilled). Between 1969 and 1973, the average number of adult and large juvenile earthworms on two replicates increased from 37 earthworms/m2 to 114 worms/m2 under direct drilling, but did not change significantly under the three cultivation treatments (21 to 80 earthworms/m2).
A replicated trial on three farms in the UK (Edwards & Lofty 1982) over five years found that one or both species of deep-burrowing earthworm Lumbricus terrestris and Allolobophora longa were significantly more abundant in untilled than in deep-ploughed plots at all three sites in all five years. After five years, untilled plots had 16.8, 8.6 and 1.2 L. terrestris/m2 on average at Woburn, Rothamsted and Boxworth experimental farms respectively, compared to 7.8, 0.3 and 0.1 L. terrestris/m2 on deep ploughed plots. Shallow working earthworm species showed few differences between untilled and ploughed treatments. In two studies with one year of monitoring, earthworms were also more abundant in untilled plots than ploughed plots. There were 250 earthworms/m2 in plots untilled for four years compared to around 50 earthworms/m2 in annually ploughed plots, and around 100 in plots ploughed for two of the four years at North Creake, Norfolk. At Lee Farm, Sussex there were between 5 and 70 L. terrestris/m2 in untilled fields, compared to between 1 and 12.5 L. terrestris/m2 in ploughed fields. There were between three and seven replicates of each treatment at each farm. The Woburn experiment on winter wheat ran from 1965 to 1971, plots were 6.4 x 18.0 m. The Rothamsted experiment on winter wheat started in 1972 with sampling from 1975 to 1979, plots were 33 x 13.5 m. The Boxworth experiment also on winter wheat started in 1971 with sampling from 1974 to 1978, plots were 36 x 13.5 m. This study is partly the same study as (Edwards 1975).
A replicated, controlled study at an arable farm over three years in England (Lee 1984) found that the effect of reduced tillage on soil invertebrate numbers was not consistent, but depended on taxa, site and year. Of the 39 beetle (Coleoptera) species analysed, 10 were more active on conventionally ploughed, 10 on minimal-tillage (tined to 10 cm and disced) and 10 on zero-tillage plots. At one of two sites, numbers of species of ground beetle (Carabidae) were significantly higher on zero-tillage plots (zero tillage: 2.8-7.3, conventional: 2.4-6.4, minimal: 2.6-6.6) and species of rove beetles (Staphylinidae) were higher on conventional plots (conventional: 8-9, minimal: 7, zero: 6-8); other beetles did not differ. Excluding beetles, invertebrate numbers showed some variation between cultivation treatments with year and site; numbers increased in conventional plots following sowing. Crane flies (Tipulidae), spiders (Araneae) and froghoppers (Cercopidae) consistently had significantly higher numbers in zero-tillage plots. Earthworm (Lumbricidae) numbers tended to be higher on zero- or minimal-tillage plots and lower on conventional plots. The replicated (two) block design was established in 1972. Between 1978-1980, the rotation comprised: spring barley/rye grass Lolium spp. and clover Trifolium spp., rye grass and clover and then winter wheat. Thirty pitfall traps/plot were sampled every 14-28 days. Earthworms were sampled by formalin extraction or hand sorting ten times/plot in April-May and September-October.
A trial at an experimental farm in 1989 on the Swiss Plateau, Switzerland (Wyss & Glasstetter 1992) found that earthworm (Lumbricidae) abundance and biomass were not higher in a no-tillage plot than other plots. No-tillage and control plots had averages of 47 and 127 earthworms/m2, and 57 and 45 g earthworm biomass/m2, respectively. There was a much higher proportion of deep-burrowing earthworms in the no-tillage plot (67% of individuals, compared to 11-14% of individuals in ploughed plots), which is why there were more individual worms in the control plot. Test strips of maize Zea mays 14 m-long were either managed with no-tillage (sowing directly into undisturbed stubble) or conventionally ploughed and harrowed. The no-tillage treatment also had rye grass Lolium spp. sown after the maize. Earthworms were sampled by hand-sorting 0.1 m3 of soil from each test strip, to a depth of 40 cm, on six dates between April and October 1989. There was no replication.
A controlled study in 1988-1990 in five plots in an arable field (Glemnitz 1993) found that weed cover was significantly higher in the conservation and minimum tillage regimes than under traditional tillage in most crops (no difference in corn and winter rye after corn). This study was presented at a conference in Germany, no location details were provided. The effect of reduced tillage on weed numbers and cover depended both on the current and previous crop in rotation. Conservation tillage led to higher weed numbers in winter rye after potatoes and in fodder radish (year 5), minimum tillage in winter rye after winter rye and both reduced tillage systems in winter rye after corn. Weed numbers in traditionally ploughed plots were higher in fodder radish (year 1). Tillage regime also affected weed community composition with some species being more dominant in traditional ploughing, others in reduced tillage systems. The following tillage regimes were used: traditional ploughing (18-30 cm deep), conservation tillage (combination of ploughing and non-ploughing, 10-15 cm) and minimum tillage (combination of ploughing and non-ploughing, 10-15 cm) on a crop rotation with five crops (potatoes, winter rye with catch crop, corn, winter rye, winter rye with catch crop). Plants were surveyed on 1 m2 quadrats with 8-10 replicates/crop. Surveys were conducted two to three times yearly in 4 m2 unsprayed plots. Number of plants, weed cover, crop cover and species composition (number and frequency of species) were recorded in crops (except potatoes) and catch crops.
A site comparison study at the Lovinkhoeve Experimental Farm, Noordoostpolder, the Netherlands (Ruiter et al. 1993) found greater biomass of microbes, protozoa, nematodes (Nematoda) and earthworms (Lumbricidae), but not of mites (Acari) and springtails (Collembola), in the upper 10 cm of an arable soil with reduced tillage and reduced fertilizer and pesticide inputs, than in a conventionally managed soil. At lower depth (10-25 cm), there were no consistent differences in soil fauna. The reduced tillage plot had 8.9 kg C/ha of earthworms in the top 10 cm, and 4.7 kg C/ha at 10-25 cm depth. No earthworms were recorded in conventional plots. Total biomass of nematodes in the upper layer was 0.79 kg C/ha in the reduced tillage plot, and 0.30 kg C/ha in the conventional plot. Reduced tillage plots were cultivated to 12-15 cm depth without inversion of the topsoil, compared to 20-25 cm deep ploughing on conventional plots. They also had reduced nitrogen and pesticide applications. The experiment began in 1985. Soil samples were taken from three areas of each plot under winter wheat in 1986.
A replicated, controlled, randomized study of cultivation treatments from 1989 to 1992 on an arable farm 3 km from Long Ashton Research Station, England (Kendall et al. 1995) found more money spiders (Linyphiidae) and slugs (Gastropoda) on arable soil after direct-drilling than after ploughing. Rove beetle (Staphylinidae) and ground beetle (Carabidae) numbers were not consistently different between treatments. In one field in autumn and winter, money spider numbers tended to be higher following direct-drilling (1-9/trap/week) than non-inversion (1-4) or ploughing (1-4), whereas in summer, numbers were higher on cultivated (16-25/trap/week) compared to direct-drilled plots (9-16). In the second field studied, no difference between treatments was found. Eight beetle (Coleoptera) groups tended to be more prevalent on ploughed plots (smaller beetles), 11 on Dutzi cultivated and/or direct-drilled plots (larger beetles); nine beetle groups showed no difference between treatments. Slug numbers tended to be higher on direct-drilled (4-9/sample) and non-inversion tillage plots (1-16) than ploughed plots (1-4). Plots of 30 or 50 x 12 m of each treatment were randomized in three or five replicated blocks in two winter cereal fields (3-4 ha). Half of each plot received a selective pesticide for aphids (Aphidoidea) in 1990-1991. Predators were sampled using two pitfall traps/plot for seven days each month from 1989 to 1992. Slugs were monitored by flooding a soil sample from each plot at one to six month intervals. Results for other pest species, crop damage and the effects of incorporating straw are not included here.
A replicated, controlled study of two fields on two farms in Saxony, Germany from 1991 to 1992 (Heimbach & Garbe 1996) found that conservation tillage plots (with catch crops of phacelia Phacelia tanacetifolia or white mustard Sinapis alba) without seed-bed preparation in the spring resulted in an increase in spiders (Araneae), rove beetles (Staphylinidae) and ground beetles (Carabidae). Spider and ground beetle density was higher in conservation tillage plots without tillage in spring (spiders: 32-85/m², ground beetles: 6-21/m²) compared to those with tillage (15-38, 2-14/m² respectively). However rove beetle abundance differed between catch crops: rove beetles no tillage: 70-95/m² in phacelia, 54-100/m² in white mustard; tillage in spring: 50-83/m² in phacelia, 84-148/m² in white mustard. Plots with conservation tillage had higher numbers of all three taxa than conventional plots (spiders: 10-18/m², rove beetles: 43-62/m², ground beetles: 2-11/m²). Numbers tended to be higher when white mustard was used compared to phacelia, particularly for ground beetles (4-21 vs 2-17/m²). Fields were divided into plots (12-24 x 100 m) with two replicates of five soil cultivations: conventional (ploughed, tillage, drilling of sugar beet Beta vulgaris) or conservation tillage with phacelia or white mustard (ploughed, tillage and drilled) followed by soil tillage and drilling or direct drilling of sugar beet in spring. Insecticides were not applied where predatory arthropods were monitored. Two ground photo-eclectors with a pitfall trap were used in each plot and were emptied and moved 1-2 times/week from sugar beet drilling until the end of June. Pest data are not included here.
A replicated, controlled study of arable cultivation over one year in Belgium (Baguette & Hance 1997) found that reduced tillage did not increase ground beetle (Carabidae) abundance or species richness. Ground beetle abundance was higher in conventionally ploughed plots (30 cm: 4,073-6,166 individuals) than those with reduced tillage (15 cm: 3,361-4,496) or no ploughing (2,604-3,577), largely due to one dominant species Pterostichus melanarius in ploughed fields. Abundance varied with crop type. Species richness also varied with crop type (beet: 13-14 species, wheat: 14-15, barley: 14-16, maize: 15-16) but not treatment (ploughed: 13-15, reduced tillage: 13-16, none: 14-16). However, less abundant species in conventionally ploughed plots tended to increase with reduced or no tillage. No-tillage plots received 30 kg/ha nitrogen and herbicide. Ground beetles were sampled using six pitfall traps in two plots (40 x 20 m) per treatment and crop. Traps were collected weekly from April until harvest in 1982.
A controlled trial at Reinshof experimental farm, Lower Saxony, Germany (Krooss & Schaefer 1998) found that the number of adult rove beetles (Staphylinidae) was similar in ploughed and unploughed wheat field plots, but there were more beetle larvae in unploughed plots. Ten rove beetle species (of a total of 94 species or types) preferred soils with reduced tillage as larvae and adults. The experiment was carried out on four wheat fields, half ploughed and half subject to non-inversion tillage, in 1992 and 1993. Four pitfall and four emergence traps were set in each half of each field and monitored throughout the year, or from April to July respectively. Each field was managed under a different farming system, as part of another experiment, so the four fields were not replicates.
A randomized, replicated, controlled trial from 1990 to 1992 in Suffolk, UK (McCloskey et al. 1998), found that abundance of the grass weed, sterile brome Bromus sterilis, increased ten-fold each year in plots with minimum tillage, but did not increase in ploughed plots. This was true on plots where sterile brome was sown alone, with other weed species or control plots with weeds unsown. Numbers of other weeds - common poppy Papaver rhoeas and cleavers Galium aparine, remained low on most plots and did not show a consistent difference between ploughed and minimum tillage plots. From October 1989 winter wheat plots were either ploughed to a depth of 22 cm or minimum-tilled to a depth of 6 cm. Minimum tilled plots were treated with conventional herbicides used to control grass weeds in cereals. Ploughed plots were selectively weeded and hoed by hand twice a year at most. There were three 9 m2 replicate plots for each combination of treatments. Weed growth was monitored from 1990 to 1992.
A paired site comparison study on two farms, at Relliehausen and Grossobringen, Germany (Rohrig et al. 1998), found significantly more potworms (Enchytraeidae) in plots under reduced tillage than conventionally ploughed treatments. There were averages of 8,265-8,664 potworms/m2 under reduced tillage, and 3,620-6,296 potworms/m2 under conventional tillage. In plots with reduced tillage, more than 60% of potworms were in the upper 10 cm of soil at both sites. In deep ploughed plots, the potworms were distributed down to 25 cm deep. Conventional treatments were ploughed to 25-30 cm depth at both sites. The reduced tillage treatments were conservation tillage with a rotary harrow to a depth of 12 cm, incorporating mulch at Relliehausen, and shallow ploughing to 12 cm at Grossobringen. The systems had been in place since 1990. In spring 1995, potworms were extracted from fifteen 25 cm deep soil cores, divided into 5 cm layers, in each tillage system.
A replicated controlled trial at the University of Agriculture, Nitra, Slovakia (Gallo & Pekar 1999) found that flying insects in an organic wheat crop - both pests and predators - were more abundant after minimum tillage than after ploughing. Pest insects, excluding aphids (Aphidoidea), were generally more abundant under minimal tillage in a given year. This group included 11 different types of thrip (Thysanoptera), bug (Hemiptera), beetle (Coleoptera), sawfly (Hymenoptera), moth (Lepidoptera) and fly (Diptera). Natural enemies, which included flies, wasps (Hymenoptera) and beetles were also generally more abundant after minimal tillage than after ploughing, although the effect was less strong and not true for hoverflies (Syrphidae). Natural enemy insects were more affected by the previous crop, being more abundant in wheat following a maize crop. Two 50 m2 study plots were ploughed to 24 cm deep, and two were ploughed to 15 cm deep (minimal tillage) each year from 1994 to 1996, and planted with winter wheat. Insects were collected with a sweep net in 5 m2 patches of each plot, weekly from April or May to June or July in 1995, 1996 and 1997.
A 1999 literature review (Kromp 1999) found that reduced tillage (either shallow ploughing, ‘conservation’ tillage or no tillage) has been shown to enhance ground beetle (Carabidae) numbers in four European studies (including (Heimbach & Garbe 1996)) relative to conventional ploughing. One European study showed no difference in numbers between conventionally ploughed and reduced tillage fields (Paul 1986). One European study (Baguette & Hance 1997) showed greater numbers of ground beetles on deep ploughed fields than under reduced tillage. However, different species responded differently. One study (Baguette & Hance 1997) listed seven ground beetle species associated with reduced tillage or untilled plots.
Paul W.-D. (1986) Vergleich der epigäischen Bodenfauna bei wendender bzw. nichtwendender Grundbodenbearbeitung. Mitteilungen aus der Biologischen Bundesanstalt für Land und Forstwirtschaft, Berlin-Dahlem, 232-290.
A paired sites study in 1993-1999 on arable fields in Gülzow, north Germany (Gruber et al. 2000) found that reduced tillage could lead to higher weed densities and higher weed species numbers compared to ploughing. Single weed species were affected differently by the tillage method in different crops. For example, goosefoot Chenopodium album and couch grass Elymus repens were observed more frequently under reduced tillage than after ploughing in summer cereals, but less frequently in reduced tillage winter cereals. The opposite was found for others such as knotweed species Polygonum spp. and common chickweed Stellaria media, which were more frequent in ploughed than in reduced tillage summer cereal fields, whereas in winter cereals they were more frequent under reduced tillage. Fields were divided into one organically and one integrated managed part (0.55-1.1 ha). Within each management system, two types of soil preparation (ploughing and reduced tillage) were compared. The 6-year crop rotation included clover Trifolium spp.-grass ley, potatoes/corn, spring barley, fodder peas, winter wheat/rye and oat undersown with red clover T. pratense. Mechanical weed control was adopted on the organic fields. Herbicide use in the integrated system was adapted to the actual weed abundance. Weed density (plants/m2), weed cover (%) and species number were recorded yearly before weed control activities on four plots (from 1997) in each field. Note that no statistical analyses have been performed on the data presented in this paper.
A 2000 literature review (Holland & Luff 2000) looked at which agricultural practices can be altered to benefit ground beetles (Carabidae). It found one study from Europe showing more ground beetles after non-inversion tillage (Heimbach & Garbe 1995). One European study found no effect of tillage on ground beetle numbers (Huusela-Veistola 1996). Two studies from Europe, showed that different species respond differently (Hance & Gregoire-Wibo 1987, (Kendall et al. 1995)).
Hance T. & Gregoire-Wibo C. (1987) Effect of agricultural practices on carabid populations. Acta Phytopathologica et Entomologica Hungarica, 22, 147-160.
Heimbach U. & Garbe V. (1995) Effects of reduced tillage systems in sugar beet on predatory and pest arthropods. Acta Jutlandica, 71, 195-208.
Huusela-Veistola E. (1996) Effects of pesticide use and cultivation techniques on ground beetles (Col, Carabidae) in cereal fields. Annales Zoologici Fennici, 33, 197-205.
A 2001 review of published literature (Chan 2001) found seven studies showing higher earthworm (Lumbricidae) populations under conservation tillage, with two to nine times more earthworms than under conventional tillage. Three of these studies were European studies considered above (Barnes & Ellis 1979, Gerard & Hay 1979, Edwards & Lofty 1982), one was in Australia, two in the USA and one in the tropics. Two studies in the UK and one in Switzerland (Gerard & Hay 1979, Edwards & Lofty 1982, Wyss & Glasstetter 1992), found more large-bodied deep-burrowing earthworms under no-tillage, and similar numbers or fewer smaller-bodied, not deep burrowing worms under no-tillage compared with conventional ploughing.
A replicated, controlled trial in Rhine-Hessia, Germany from 1995 to 1998 (Emmerling 2001) found that soils managed with layer cultivation (conservation tillage) had more adult and juvenile earthworms (Lumbricidae), and a greater biomass of earthworms, than soils that were ploughed or two-layer ploughed. In most cases there were twice as many worms under layer cultivation. For example, there were 22 Lumbricus terrestris individuals under layer cultivated winter rye, compared to nine in ploughed fields and seven in two-layer ploughed fields. Four earthworm species were found in ploughed fields, five to six species in two-layer ploughed fields and six to seven species in fields under layer cultivation. Ploughing, two-layer ploughing (shallow turning to 15 cm, soil loosening to 30 cm) and layer cultivation (also called conservation tillage, only loosening the soil to 30 cm depth, no turning) were tested on ten 12 x 100 m plots. There were five different crop types in the experiment - green fallow, winter wheat with intercrop, peas, winter rye with intercrop and summer barley. Each crop/tillage combination was replicated twice. Crop type did not have a significant effect on the number or biomass of earthworms.
A replicated controlled trial at the University of Agriculture, Nitra, Slovakia (Gallo & Pekar 2001) found that predatory insects were more abundant after minimum tillage than after deep ploughing in a conventionally farmed wheat crop. Most pest insects were less abundant in a given year under minimal tillage than in ploughed plots. This group included thrips (Thysanoptera), bugs (Hemiptera), beetles (Coleoptera), sawflies (Hymenoptera), moths (Lepidoptera) and flies (Diptera). Only sawflies in the family Tenthredinidae and some bugs (Heteropetera) were more abundant on minimal tillage plots. Natural enemies, which included flies (Diptera), wasps (Hymenoptera) and beetles (Coleoptera) were more abundant after minimal tillage than after ploughing, although this was not true for hoverflies (Syrphidae). Pest insects were less abundant after minimum tillage. Two 50 m2 study plots were ploughed to 24 cm deep, and two were ploughed to 15 cm deep (minimal tillage) each year from 1994 to 1996, and planted with winter wheat. Insects were collected with a sweep net in 5 m2 patches of each plot, weekly from April or May to June or July in 1995, 1996 and 1997.
A replicated, controlled, randomized study of conventional and non-inversion tillage in six fields in Somerset, UK (Hutcheon et al. 2001) found that earthworm (Lumbricidae) abundance and species diversity were higher in non-inversion regimes using a Dutzi machine than in either non-inversion farming using a Vaderstad drill or conventional ploughing and drilling. From 1990-1994 there was no significant difference between density in Dutzi non-inversion plots (65/m²) and conventional plots (64/m²), but biomass was significantly greater in Dutzi plots in 1993 and 1994 (23-40 vs 13-16 g/m²). From 1995-2000, worm density was significantly greater in Dutzi plots than conventional plots in 1995, 1999 and 2000 (72-155 vs 38-66/m²); Vaderstad non-inversion plots did not differ from conventional plots (62-72 vs 38-66/m²). Biomass was significantly greater in Dutzi than conventional plots in all but one year (35-68 vs 16-31 g/m²); biomass in Vaderstad plots was only greater than conventional plots in two years (33-42 vs 16-19 g/m²). Thirteen species were recorded from 1995 to 2000, four of which were significantly more abundant in Dutzi than conventional plots; densities in Vaderstad plots were intermediate. There was no significant effect of treatment on the other six common species, although densities of four tended to be higher in Dutzi than conventional plots. Fields were divided into four plots (1 ha) which were assigned randomly to treatments. In autumn 1994-2000, an additional non-inversion tillage regime was included, using a Vaderstad disc coulter drill. Fertilizers and pesticides were also reduced (25-40% and 30-90% respectively) in non-inversion tillage regimes compared to conventional farming. Earthworms were sampled over one hour using diluted formalin on the soil in three quadrats (0.25 m²) placed at random/plot in March-April and September-October each year.
A small replicated trial in 1997 at an experimental farm in Normandy, France (Cortet et al. 2002) (same study as (Chabert & Beaufreton 2005)), found that the biodiversity of small arthropods (mites (Acari), springtails (Collembola) and others) was higher on arable land without deep ploughing than on conventionally ploughed land. This difference was true for five of the six monitoring months, from January to June 1997. The comparison was replicated on two fields. The land not ploughed in 1997 had been managed under integrated farm management for the previous eight years, and had been treated with significantly less insecticide and fungicide on average (but not less herbicide) than the conventional treatment over five cropping years. Another replicate of the integrated and conventional management was not tilled in 1997. Here there was not such a consistent difference in diversity of small arthropods. The authors concluded that tillage had more influence on small soil arthropods than reduced pesticide use.
A replicated, controlled study in the winters of 2000-2003 in 63 experimental and 58 control winter wheat and barley fields in Oxfordshire, Leicestershire and Shropshire, UK (Cunningham et al. 2002), found that significantly more beetle (Coleoptera) larvae and earthworms (Lumbricidae) were recorded in non-inversion tillage fields than in conventionally-tilled fields (no data given). The opposite was true for rove beetles (Staphylinidae). Ground beetles (Carabidae) and spiders (Araneae) showed no significant differences between treatments. This study was part of the same experimental set-up as (Cunningham 2004, Cunningham et al. 2005).
A replicated, controlled before-and-after trial on the agricultural research farm at Rugballegaard in East Jutland, Denmark (Petersen 2002) found no difference in the total abundance of springtails (Collembola) between conventionally ploughed and reduced tillage plots. The total number of springtails fell from around 90,000/m2 to around 30,000/m2, shortly after both tillage treatments. The distribution of springtails at different depths in the soil differed between treatments. After ploughing, there were significantly fewer springtails in the upper 4 cm of the soil on ploughed plots and an increase in springtail numbers at 16-20 cm depth (statistically significant for some species only). This was thought to be caused by the inversion of soil during ploughing. Two tillage methods were tested on four areas of organic wheat fields from 1998 to 1999: conventional mouldboard ploughing to 20 cm depth followed by harrowing, or deep tillage with a non-inverting tine subsoiler to 25-35 cm depth, rotavated at the surface. The first samples were taken in September 1998, before the first tillage treatment. Springtails were extracted from soil samples at three locations in each plot, and at four depths: 0-4, 8-12, 16-20 and 28-32 cm. Subsequent samples were taken in October 1998 (two samples) and March 1999.
A replicated, controlled study in the winters of 2001-2003 in 20 experimental and 20 control winter wheat fields at seven farms in Leicestershire and Shropshire, UK (Cunningham 2004) found that there was no significant difference in earthworm (Lumbricidae), ground beetle (Carabidae), rove beetle (Staphylinidae) or spider (Araneae) numbers in non-inversion tillage fields compared to conventionally-tilled fields. Beetle (Coleoptera) larvae showed some tendency for higher numbers in conventional (1.2) compared to non-inversion tillage (0.5) in July, but not March or May. The mean number of seed species per field did not differ significantly between treatments in autumn (17-18/m²) or spring (15-16/ m²). Nine samples for earthworms and seeds were taken in October-November and March and for arthropods in March, May and July. Earthworms were sampled in 10 cm diameter by 10 cm deep cores, seeds in surface soil samples of 25 cm² and 1 cm deep and spiders and insects in pitfall traps. This study was part of the same experimental set-up as (Cunningham et al. 2002, Cunningham et al. 2005).
A 2004 review of the effects of non-inversion tillage on beetles (Coleoptera), spiders (Araneae), earthworms (Lumbricidae) and farmland birds across the world, but with special reference to the UK and Europe (Cunningham et al. 2004) found evidence for some positive responses. It found one three-year study from the UK ((Cunningham et al. 2002), Cunningham et al. 2003, (Cunningham et al. 2005)) that found Eurasian skylark Alauda arvensis, gamebirds and seed-eating songbirds were more abundant on non-inversion tillage fields in late winter compared to conventional tillage. Two studies found more beetles in reduced or no tillage plots (Andersen 1999, Holland & Reynolds 2003); four studies found mixed results. Two out of three studies found positive effects of reduced or non-inversion tillage on spiders ((Kendall et al. 1995), Holland & Reynolds 2003). Ten out of 13 studies found positive effects of reduced or non-inversion tillage on earthworms.
Andersen A. (1999) Plant protection in spring cereal production with reduced tillage. II. Pests and beneficial insects. Crop Protection, 18, 651-657.
Cunningham H.M., Chaney K., Bradbury R.B. & Wilcox A. (2003) Non-inversion tillage and farmland birds in winter. Proceedings of the British Crop Protection Council Congress - Crop Science & Technology. Farnham, UK, pp 533-536.
Holland J.M. & Reynolds C.J.M. (2003) The impact of soil cultivation on arthropod (Coleoptera and Araneae) emergence on arable land. Pedobiologia, 47, 181-191.
A 2004 review of the effects of conservation tillage relative to conventional ploughing (Holland 2004) mainly but not exclusively focussing on European studies, found that earthworms (Lumbricidae) almost always benefit from conservation tillage, but effects are more mixed for other organisms, including plants, birds and mammals. Four European experimental studies and two reviews showed that conservation tillage increased earthworm populations, particularly deep-burrowing species such as Lumbricus terrestris, with up to six times more earthworms under conservation tillage in the context of integrated farming (including: (Edwards & Lofty 1982), El Titi & Ipach 1989, Jordan et al. 2000, Kladivko 2001). Conservation tillage increased the diversity and abundance of springtails (Collembola) and mites (Acari) in four studies (Bertolani et al. 1989, El Titi & Ipach 1989, Vreeken-Buijs et al. 1994, Franchini & Rockett 1996). European studies on larger arthropods (beetles (Coleoptera) and spiders (Araneae)) were less consistent, with two studies showing increased numbers under conservation tillage ((Kendall et al. 1995), Purvis & Fadl 1996), one showing no effect (Huusela-Veistola 1996) and two showing both increases and decreases (Andersen 1999, Holland & Reynolds 2003). Different arthropod species were affected differently. Four UK studies showed an increase in grass species classed as weeds under conservation tillage (Theaker et al. 1995, Rew et al. 1996, Cavan et al. 1999, (McCloskey et al. 1998)). Other weed species have been shown to decline under conservation tillage in the context of integrated farming (one German study; Albrecht & Mattheis 1998) or remain stable (one UK study; (McCloskey et al. 1998)). For birds, one study showed no effect on five bird species in the context of organic farming (Saunders 2000). For mammals, one European study found that wood mice Apodemus sylvaticus were more abundant on conventionally ploughed fields than under conservation tillage in the context of organic and integrated farming (Higginbotham et al. 2000).
Bertolani R., Sabatini M.A. & Mola L. (1989) Effects of changes in tillage practices in Collembola populations. Pages 291-297 in: R. Dallai (ed.) Proceedings of the Third International Symposium on Apterygota, Siena.
El Titi A. & Ipach A. (1989) Soil fauna in sustainable agriculture: results of an integrated farming system at Lautenbach, FRG. Agriculture, Ecosystems and Environment, 27, 561-572.
Vreeken-Buijs M.J., Geurs M., de Ruiter P.C. & Brussaard L. (1994) Microarthropod biomass-c dynamics in the belowground food webs of two arable farming systems. Agriculture, Ecosystems and Environment, 51, 161-170.
Theaker A.J., Boatman N.D. & Froud-Williams R.J. (1995) The effect of nitrogen fertiliser on the growth of Bromus sterilis in field boundary vegetation. Agriculture, Ecosystems and Environment, 53, 185-192.
Franchini P. & Rockett C.L. (1996) Oribatid mites as “indicator” species for estimating the environmental impact of conventional and conservation tillage practices. Pedobiologia, 40, 217-225.
Huusela-Veistola E. (1996) Effects of pesticide use and cultivation techniques on ground beetles (Col, Carabidae) in cereal fields. Annales Zoologici Fennici, 33, 197-205.
Purvis G. & Fadl A. (1996) Emergence of Carabidae (Coleoptera) from pupation: a technique for studying the ‘productivity’ of carabid habitats. Annales Zoologici Fennici, 33, 215-223.
Rew L.J., Froud-Williams R.J. & Boatman N.D. (1996) Dispersal of Bromus sterilis and Anthriscus sylvestris seed within arable field margins. Agriculture, Ecosystems and Environment, 59, 107-114.
Albrecht H. & Mattheis A. (1998) The effects of organic and integrated farming on rare arable weeds on the Forschungsverbund Agrarokosysteme Munchen (FAM) research station in southern Bavaria. Biological Conservation, 86, 347-356.
Andersen A. (1999) Plant protection in spring cereal production with reduced tillage. II. Pests and beneficial insects. Crop Protection, 18, 651-657.
Cavan G., Cussans G. & Moss S.R. (1999) Modelling strategies to prevent resistance in black-grass (Alopecurus mysosuroides). Presented at Brighton Crop Protection Conference on Weeds, pp. 777–782.
Higginbotham S., Leake A.R., Jordan V.W.L. & Ogilvy S.E. (2000) Environmental and ecological aspects of integrated, organic and conventional farming systems. Aspects of Applied Biology, 62, 15-20.
Jordan V.W., Leake A.R. & Ogilvy S.E. (2000) Agronomic and environmental implications of soil management practices in integrated farming systems. Aspects of Applied Biology, 62, 61-66.
Saunders H. (2000) Bird species as indicators to assess the impact of integrated crop management on the environment: a comparative study. Aspects of Applied Biology, 62, 47-54.
Kladivko E.J. (2001) Tillage systems and soil ecology. Soil and Tillage Research, 61, 61-76.
Holland J.M. & Reynolds C.J.M. (2003) The impact of soil cultivation on arthropod (Coleoptera and Araneae) emergence on arable land. Pedobiologia, 47, 181-191.
A randomized, replicated controlled trial in spring 1999 and 2000 at the Rugballegaard Institute of Agricultural Sciences, Denmark (Thorbek & Bilde 2004) found that both soil loosening and non-inversion tillage have adverse effects on ground beetles (Carabidae) and spiders (Araneae), but for non-inversion tillage these are not quite as severe as the effects of ploughing. There were around 20 ground beetles/m2 immediately after non-inversion tillage, compared to around 12 ground beetles/m2 after ploughing and around 18 in untreated control plots. There was no difference between ploughing and non-inversion tillage plots in numbers of spiders or rove beetles (Staphylinidae), or in any of the three arthropod groups 26 days after the treatment. Overall, neither ploughing nor non-inversion tillage immediately reduced the numbers of predatory arthropods significantly, relative to untreated control plots, but all three groups had lower numbers in ploughed or non-inversion tilled plots 26 days later than in untreated control plots (for example <5 spiders and <20 ground beetles/m2 in both ploughed and non-inversion tillage plots, compared to around 25 spiders and 130 ground beetles/m2 in control plots). In a separate experiment, soil-loosening to 8 cm depth with a tined hoe immediately reduced spider numbers by 25% (around 120 spiders/m2 in control plots and 90 spiders/m2 in treated plots) and ground beetle numbers by 51% (around 70 ground beetles/m2 in control plots, 35 ground beetles/m2 in treated plots) but not rove beetle numbers. These differences were statistically significant and persisted in a second sample 18 days later. The treatments were replicated between four and eight times, on 12 x 40 m plots. Predatory arthropods were sampled using emergence traps.
A small replicated trial at an experimental farm in Normandy, France (Chabert & Beaufreton 2005) (same study as (Cortet et al. 2002)) found more spiders (Araneae) and ground beetles (Carabidae), but fewer rove beetles (Staphylinidae) in arable plots managed without deep ploughing than in plots with conventional ploughing. The unploughed plots were also managed with limited used of herbicides and fungicides, and no insecticides, so it is difficult to separate the effects of ploughing from the effects of reducing pesticide use. However, both ground beetles and spiders were also more abundant in subplots that restricted pesticide and herbicide use even more, whereas rove beetles were not. There were three replicates of each treatment. Management was over eleven years from 1990 to 2001. Insects and spiders were monitored in May and June from 1999 to 2001.
A replicated, controlled study in the winters of 2000-2003 in 63 experimental and 58 control winter wheat and barley fields in Oxfordshire, Leicestershire and Shropshire, UK (Cunningham et al. 2005) found that Eurasian skylark Alauda arvensis, seed-eating songbirds and gamebirds occupied a significantly higher proportion of fields managed through non-inversion tillage than conventionally ploughed fields in late winter (January-March). Species richness of seed-eating songbirds was also higher on non-inversion tillage fields (five species vs one on conventionally ploughed fields). No birds showed any preference for field type in early winter (October to December), and crows (Corvidae), pigeons (Columbidae) and insect-eating birds showed no preference across the study period. Field size ranged from 1.6 to 22.3 ha, with similar numbers of non-inversion tillage and conventionally-ploughed farms censused each year. This study was part of the same experimental set-up as (Cunningham et al. 2002, Cunningham 2004) and is also described in an additional publication (Cunningham et al. 2003).
Cunningham H.M., Chaney K., Bradbury R.B. & Wilcox A. (2003) Non-inversion tillage and farmland birds in winter. Proceedings of the British Crop Protection Council Congress - Crop Science & Technology. Farnham, UK, pp 533-536.
A replicated, controlled trial at the Oakpark Research Centre, County Carlow, Ireland (Brennan et al. 2006), found that winter wheat plots subjected to a reduced tillage regime for three years had more springtails (Collembola) in the soil than conventionally ploughed plots. Conventional plots had around 100 springtails/m2 and ‘ECOtilled’ plots had over 300 springtails/m2 on average. Sixteen 24 x 30 m plots were established in 2000 and sown with winter wheat every year. ‘ECOtillage’ plots were cultivated with a shallow cultivator 5-10 cm deep after harvesting. Weeds were sprayed with herbicide, and the crop was sown with a cultivator drill. Control plots were ploughed with a mouldboard plough to a depth of 25 cm and cultivated with a power harrow (10-15 cm) before sowing. At harvest, straw was either baled and removed or chopped and replaced on the soil surface. There were four replicates of each treatment combination, and 12 m buffer strips around each plot. Springtails were extracted from soil samples in 2003.
A replicated, controlled, randomized study of cultivation techniques at the Lithuanian Institute of Agriculture (Kinderienė 2006) found that earthworm (Lumbricidae) abundance tended to be higher under reduced tillage than deep ploughing. In 2000, the number of earthworms was higher in plots with reduced tillage (42-97 m²) than ploughed plots (with and without straw; 38-80/m²), there was no difference in 2001. Compared to deep ploughing, earthworm population density increased through soil conservation technology using several measures (straw disced-in, catch crop, not ploughed) by 53/m² (141%) in wheat stubble and 40/m² (103%) in oat stubble, there was no effect in barley stubble. Earthworm numbers in ploughed soil with straw incorporated and a catch crop were significantly larger (by 28/m²) in one of the three years. Intensive soil tillage (straw, shallow discing, herbicide, deep ploughing) did not affect earthworm density. There were four replicates of eight treatments: conventional and conservation soil tillage in combination with chopped straw mulch (wheat or barley), catch crop (white mustard Sinapis alba) and herbicide (Roundup; 3 l/ha) application. Earthworms were counted in four replications (0.25 m², depth 25 cm) in three locations in each plot in April 2000-2002.
A 2006 review (Stockdale et al. 2006) of the impact of farm management practices on below-ground biodiversity and ecosystem function found tillage had negative effects on beetles (Coleoptera), springtails (Collembola), mites (Acari), spiders (Araneae), and earthworms (Lumbricidae). The review looked at studies worldwide but here we focus on European studies. One review (Wardle 1995) (location not provided) concluded that tillage tends to reduce large soil organisms (beetles, spiders and earthworms) more than the smallest ones (bacteria, fungi), and that intermediate-sized groups (nematodes (Nematoda), mites and potworms (Enchytraeidae)) can show small population increases. Two studies (one from Sweden, one review) demonstrated the direct negative effects of tillage on mites, springtails, and beetles (Andren & Lagerlöf 1980, Wardle 1995); and a further study showed that compaction during tilling can reduce the number of earthworms and microarthropods (Aritajat et al. 1977; location not given). One study from Denmark showed that tillage reduced the springtail population to about 1/3 of the pre-tillage level one week after cultivation (Petersen 2002). Two studies (one study from Switzerland) noted differences in the species composition of arbuscular mycorrhizal fungi, earthworms and nematodes (Nematoda) between tillage and no-till systems (Wardle 1995, Jansa et al. 2003). Two studies (one study from Germany) investigated the impact of tillage on the balance between bacteria and fungi, with mixed results (Wardle 1995, Ahl et al. 1998). One study from the UK found that invertebrate food resources for birds increased in no-till compared to conventionally tilled systems (Tucker 1992).
Aritajat U., Madge D.S., & Gooderham P.T. (1977) Effects of compaction of agricultural soils on soil fauna .1. Field Investigations. Pedobiologia, 17, 262-282.
Andren O. & Lagerlöf J. (1980) The abundance of soil animals (microarthropoda, enchytraeids, nematoda) in a crop rotation dominated by ley and in a rotation with varied crops. Pages 274-279 in: D. L. Dindal (ed.) Soil Biology is related to land-use practices. Environmental Protection Agency, Washington.
Tucker G. M. (1992) Effects of agricultural practices on food use by invertebrate feeding birds in winter. Journal of Applied Ecology, 29, 779-790.
Wardle D. A. (1995) Impacts of disturbance on detritus food webs in agro-ecosystems of contrasting tillage and weed management practices. Advances in Ecological Research, 26, 105-185.
Ahl C., Joergensen R.G., Kandeler E., Meyer B., & Woehler V. (1998) Microbial biomass and activity in silt and sand loams after long-term shallow tillage in central Germany. Soil and Tillage Research, 49, 93-104.
Jansa J., Mozafar A., Kuhn G., Anken T., Ruh R., Sanders I.R. & Frossard E. (2003) Soil tillage affects the community structure of mycorrhizal fungi in maize roots. Ecological Applications, 13, 1164-1176.
A replicated, controlled study in May to July 2003-2004 in two arable regions in central Germany (Volkmar & Kreuter 2006) found that the abundance/activity density of both spiders (Araneae) and ground beetles (Carabidae) was higher on fields with reduced tillage (ground beetles: 1,446 individuals (mulched fields), 1,634 (directly sown fields); spiders: 4.75 individuals/day and trap (mulching), 2.9 (direct sown)) than on conventional ploughed fields (ground beetles: 1,241 individuals; spiders: 2.85 individuals/day and trap), but lower than on organic ploughed fields (ground beetles: 2,725 individuals; spiders: 6.05 individuals/day and trap). Species richness of spiders was higher on reduced tillage fields (direct sown: 40 species, mulched: 35 spp.) than on the other field types (organic: 37.5 spp., conventional ploughed: 35 spp.), but the number of ground beetle species was lower on reduced tillage fields (mulched: 35.5 spp., direct sown: 34 spp.) than on the other field types (39 spp. conventional ploughed, 50 spp. organic ploughed). However, the effect of reduced tillage was species dependent for both spiders and ground beetles, i.e. some species clearly benefited from reduced tillage, whereas others preferred ploughed fields. Four field types were investigated: organic ploughed fields, conventional ploughed fields, conventional mulched fields (no plough), and conventional directly sown fields (no plough). Cereals were grown on all fields during the study years. Spiders and ground beetles were caught using pitfall traps (six replications/field type). Note that no statistical analyses were performed on the data presented in this study.
A replicated site comparison study in 2005 and 2006 on 31 farms in Seine-et-Marne, France (Chateil et al. 2007) reported in the text that the number of plant species was higher on no-till farms than conventional farms, but the data presented on a graph in this paper appeared to show no difference, with five plant species on both types of farm. Twenty-six fields from 17 farms were sampled three times in 2005 (April, June, September). Sixty-four fields from 31 farms (including all those surveyed in 2005) were sampled twice in 2006 (April and July). Plants were recorded in ten permanent, regularly spaced, 1 m2 (0.5 x 2 m) quadrats along the permanent margins of each field. The difference between different ploughing systems was only found in 2006.
A replicated, paired site study from October to March 2003-2006 in 12 pairs of winter wheat fields in Dióskál, Hungary (Field et al. 2007a) found that the preference of some farmland birds for conservation tillage fields over adjacent ploughed fields decreased over the study period. In the first farm (with eight field pairs), Eurasian skylark Alauda arvensis and seed-eating songbirds (mostly goldfinch Carduelis carduelis) were more abundant on conservation tillage fields in the first winter (2003-2004), whilst European starling Sturnus vulgaris and skylark were more abundant on conservation tillage fields over the second and third winter respectively. In the second farm (four field pairs), skylark and crows (Corvidae) were more abundant on conservation tillage fields in the first winter only. The number of days with snow cover on the ground increased over the three years. The authors suggest such abnormal weather may have confounded the results.
A small replicated, randomized, controlled study from April-July 2005 in two experimental and two control fields of winter wheat in Rutland, England (Field et al. 2007b) found that Eurasian skylark Alauda arvensis nest density was higher in fields managed through conservation tillage than fields that were ploughed (24 out of 32 nests in conservation tillage fields). Average laying date was also significantly earlier on conservation tillage fields by 25 days. The authors suggest the effect was due to conservation tillage fields containing more crop residue than ploughed fields (32% compared to 0% residue respectively). Foraging distance of adult skylarks providing food for nestlings was halved on conservation tillage fields (48 m vs 93 m). However, nest success and nestling size were similar in both field types. Control fields were sown with winter wheat after mould-board ploughing, while conservation tillage fields were direct drilled into oilseed rape residue after light rotary harrow.
A replicated controlled trial at the University of Kassel experimental farm, Frankenhausen, Germany, (Metzke et al. 2007) found that neither of two methods of reducing tillage suitable for use on organic farms enhanced numbers of earthworms (Lumbricidae) in the soil. Ploughing is important for weed control in organic farming, so both systems involved some soil inversion. A ridge culture system, using a shallow plough that formed ridges and loosened the soil with a spike to 35 cm depth, and a shallow inversion plough to 10 cm depth, were compared with conventional ploughing to 30 cm depth. There was no difference in the abundance or total biomass of earthworms between the conventional ploughing and shallow ploughing. On average between 5 and 30 earthworms/m2, and between 2 and 40 g earthworm/m2 were found in the different crops for these treatments. Under the ridge culture system there were significantly fewer earthworms (3-20 earthworms/m2 on average), and lower biomass of earthworms (0-27 g/m2 on average). The experiment began in 2003, with twelve replicates of each treatment. Plots were managed organically. Earthworms were monitored by hand sorting and extraction, in October 2005.
A replicated trial at Estrées-Mons, France (Capowiez et al. 2009), found that reduced tillage plots had a significantly higher average biomass of earthworms (Lumbricidae), but not a greater number of individual worms. Under reduced tillage there were 77 g earthworm/m2 and 116 earthworms/m2. Under conventional tillage, there were 37 g earthworm/m2 and 111 earthworms/m2. This difference was because there were more large, deep-burrowing worms such as Lumbricus terrestris and Aporrectodea giardi, and fewer small litter-dwelling worms such as A. caligosa in the reduced tillage plots. Soils under reduced tillage had significantly more large pores created by earthworm activity, in all size classes. Twelve 0.4 ha arable plots were subject to reduced tillage, prepared only with a rotary or disc harrow to 7 cm depth. Twelve control plots underwent conventional tillage, with a mouldboard plough to a depth of 30 cm, followed by seed bed preparation with a harrow to 7 cm. The management began in 1999. Earthworms were sampled in November after tillage and in April, from November 2003 until April 2006 (six times).
A replicated trial in the winters of 2006-2008 in four (2006-2007) and two (2007-2008) fields (located on one farm) of winter oilseed rape Brassica napus crops in Cambridgeshire, UK (Dillon et al. 2009) found that bird densities were similar between oilseed rape established using two different methods of reduced tillage (non-inversion tillage and broadcasting). Neither individual species nor groups of species (seed-eaters, probers) responded to differences in crop establishment. However, a Farmland Bird Index (which included omnivorous, carnivorous, insect-eating and seed-eating species) was significantly higher on broadcast oilseed rape fields. The authors point out that the overall densities on both treatments were still relatively low compared to other interventions (such as wild bird seed and overwinter cereal stubble). Two surveys were made in each field each month between September-March across the whole field area.
A replicated, controlled trial near Welschbillig, southern Eifel, Germany (Ernst & Emmerling 2009) found a higher biomass of large deep-burrowing earthworms (Lumbricidae) in arable soils subject to four different types of reduced tillage, compared to ploughed soils, after 10 years. There were 52-79 g deep-burrowing worm/m2 under reduced tillage, compared to 10 g/m2 in ploughed treatments. For two non-inversion tillage treatments, there were greater numbers of deep-burrowing worms. One of these treatments had mulched crop residue on the surface. On average there were 5 deep-burrowing earthworms/m2 in the ploughed treatment, compared to 21-25 deep-burrowing earthworms/m2 with non-inversion tillage. The total number of earthworms was not significantly different between tillage treatments (113-160 earthworms/m2 on average), but total mass of all earthworms was significantly higher in the disc harrow treatment than the ploughed treatment (119 g/m2 compared to 67 g/m2 under ploughing). Five tillage treatments were carried out on two replicate plots each, for ten consecutive years: conventional ploughing to 25 cm depth, non-inversion loosening of topsoil to 15 cm depth, disc harrowing and slightly loosening soil to 15 cm depth, non-inversion tillage with crop residue mulch on the surface, or no tillage with direct sowing of crop. Earthworms were sampled at the end of the experiment in spring 2008, under a winter barley crop.
A site comparison study in Komturei Lietzen, Brandeburg, Germany (Joschko et al. 2009), found that the average abundance of earthworms (Lumbricidae) in an arable soil was almost identical under conventional and reduced tillage over ten years - around 12 earthworms/m2. From September 1996 until 2006, one half of a 74 ha arable field was conventionally ploughed to a depth of 25 cm. The other half was subject to non-inversion tillage using a precision cultivator to a depth of 15-18 cm. Earthworms were collected by hand sorting from twenty-one 40 x 50 x 20 cm blocks of soil in each treatment, in September and April-May of each year. Large, deep burrowing earthworms may be underestimated by this method. When paired sample points with similar soil properties were compared, average abundance of earthworms was higher under reduced tillage in soils with fine particles (>7% fine particles) but not in sandy soils.
A replicated, controlled study from April-June in 2006-2007 in 48 conservation tillage, 31 organic and 63 conventional winter barley and wheat fields in Seine-et-Marne, France (Ondine et al. 2009) found that that bird species differed in their responses to management. Two species were more abundant in conservation tillage fields than conventional fields, whilst seven were more abundant on conservation tillage fields than on organic. One species was more abundant on conventional fields and five on organic, compared to conservation tillage. Specialist species were least abundant on conservation tillage fields, whilst insect-eating birds were more abundant. The authors point out that conservation tillage fields were more intensely managed than conventional fields and experienced much disturbance. Habitat and dietary data were used to construct a species specialization index.
A randomized, replicated, controlled trial on three organic arable farms in different regions of France (Peigne et al. 2009) found that earthworm (Lumbricidae) biomass was higher under no tillage than on the control or other reduced tillage treatments at all three sites, in at least two years. At two of the sites, there was no difference between treatments in earthworm abundance. At the other site (an irrigated farm in the Rhône Alpes region of southeastern France), earthworm abundance was also significantly higher in the no tillage treatment in two of the three sampling years. In general there were more deep-burrowing species in the no tillage treatment than other treatments. This difference was statistically significant at two of the three sites. There was no increase in the number of earthworm burrows (created by deep-burrowing earthworms) under no tillage. Four tillage treatments were compared: conventional mouldboard ploughing to 30 cm, shallow ploughing to 15-20 cm, reduced tillage with tined tools to 12-15 cm, no tillage. On each farm, three replicates of each treatment were randomly located within three blocks. Experiments began between 2003 and 2005 and were monitored annually for two to five years. Earthworms were extracted using formalin in October or April-May.
A small replicated trial near Paris, France (Pelosi et al. 2009) found no difference in the total number of earthworms or earthworm (Lumbricidae) species on direct drilled (no-till) plots compared to conventionally farmed plots, but earthworm biomass was always higher in direct drilled plots. These plots had an average of 79 g earthworm/m2, compared to 32 g/m2 on conventional plots. There was a much higher proportion of deep-burrowing species (50% of all earthworms were deep-burrowing) in the direct-drilled plots than in conventional plots (13% of all earthworms). There was also a higher proportion of litter-dwelling earthworms in the direct drilling plots (14% of all earthworms, compared to 2% in conventional plots). From 1997 to 2007 treatments were compared on 1 ha arable plots, two replicates of each treatment. The direct drilled treatment involved a continuous plant cover ‘living mulch’ with herbicides used to control weeds and no tillage. Earthworms were sampled from five sample points in each plot by chemical extraction and hand-sorting, every autumn for three years (2005-2007).
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