Action: Plant cereals in wide-spaced rows
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- One replicated, controlled randomized study and four reports from the same replicated, controlled study in the UK investigated the effects of planting cereals in wide-spaced rows on birds, invertebrates and plants. Both studies found no or inconsistent differences in plant and invertebrate abundance and/or species richness between wide-spaced row and control fields. The replicated controlled study found higher undesirable weed cover, and one study found no significant difference in weed cover in fields with wide-spaced rows compared to control fields.
- One study found significantly lower invertebrate abundances and fewer Eurasian skylark nests in wide-spaced row fields than control fields or fields with undrilled patches. However it also found an increase in the body condition of nestlings over the breeding season in wide-spaced row fields compared with control fields.
Planting cereals in widely-spaced rows can increase the proportion of farmland habitat for wildlife, including birds, arthropods and plants. Spaces between rows can be left fallow or planted with grass or legumes.
Supporting evidence from individual studies
A replicated, controlled study from April-August in 2002 and 2003 in 15 winter wheat fields in northern and eastern England (Morris et al. 2004) found that Eurasian skylark Alauda arvensis nests were significantly less abundant on fields with wide-spaced rows than on control fields or those with undrilled patches (0.16 nests/ha in fields with wide-spaced rows vs 0.18 for controls and 0.31 for fields with undrilled patches). The proportion of within-treatment foraging flights decreased over time in control and wide-spaced row fields but remained constant in fields with undrilled patches. Body condition of nestlings decreased in control nests but increased in the other treatments over the breeding season. Invertebrate abundance, particularly beetles (Coleoptera), was significantly lower on wide-spaced row fields. Bare ground was significantly more extensive in wide-spaced row fields. Three treatments were surveyed: winter wheat sown in wide-spaced rows, undrilled patches (4 x 4 m) with a density of 2 patches/ha, and conventional control winter wheat fields. Skylarks were surveyed from April to mid-August, with the number of territorial males, nests, nest productivity, nestling body condition and foraging locations recorded. Invertebrates were sampled in the crop (30 m from nearest field boundary) and in undrilled patches using suction sampling (May-July), sweep netting (May-June) and pitfall traps (June). Vegetation and bare ground cover were surveyed in twenty-four 0.25 m2 permanent quadrats/treatment. Ten of the sites were part of the same replicated, controlled study (SAFFIE – Sustainable Arable Farming For an Improved Environment) as (Ogilvy et al. 2006, Smith & Jones 2007, Smith et al. 2009).
A replicated, controlled study in 2002 and 2003 on ten farms in England (Ogilvy et al. 2006) found that wide-spaced rows offered ‘significant benefits’ to Eurasian skylarks Alauda arvensis, but details were not given. The authors note that skylark plots were more consistently beneficial. Across fields as a whole there was a higher proportion of undesirable weed cover in fields with wide-spaced rows than fields with conventional spacing (4% weed cover vs 1.5%). However, a second experiment found no effect of wide-spaced rows on weed diversity, when compared to conventional herbicide treatment. In 2002, but not 2003, there were higher abundances of wolf spiders (Lycosidae) in fields with wide-spaced rows than control fields. Invertebrates, plants and skylarks were monitored. This study was part of the same replicated, controlled study (SAFFIE – Sustainable Arable Farming For an Improved Environment) as (Morris et al. 2004, Smith & Jones 2007, Smith et al. 2009).
A replicated, controlled, randomized study from 2003 to 2005 of arable fields at three sites in the UK (Jones & Smith 2007) found that sowing in wide-spaced rows had little effect on the abundance or species diversity of weeds or arthropods. Weed species richness was higher under wide-spaced rows (3 species) compared to conventional cultivation (2 species) at one of the three sites in one year. There were three (2003) or five (2004-2005) replicate plots (3 or 4 x 24 m) per treatment at Boxworth, Gleadthorpe and High Mowthorpe. Treatments were: conventional spacing, wide-spaced rows and wide-spaced rows with spring cultivation (hoeing) between rows. Vegetation was sampled in five quadrats (0.25 m²) per plot (June 2003-2005). Arthropods were sampled using a D-Vac suction sampler (five sub-samples of 10s/plot) in a sub-set of treatments (June).
A replicated, controlled study in 2002 and 2003 of wheat fields at ten sites in England (Smith & Jones 2007) found that sowing crops in wide-spaced rows had little effect on plant cover and species richness or arthropod abundance. There was no significant difference in weed cover (1-2%), crop cover (30-48% vs 33-55%) or plant species richness (7 vs 7 species) between fields with wide-spaced rows and control fields. There was little effect of wide-spaced rows on arthropod abundance. However, in 2002, wolf spiders (Lycosidae) were more abundant in fields with wide-spaced rows (0.9 individuals) than controls (0.4), the opposite was true for rove beetles (Staphylinidae: 4 vs 6 individuals in fields with wide-spaced rows and controls respectively). Wide-spaced rows were sown at double the normal width (25 cm between rows). Vegetation composition was sampled within 24 quadrats (0.25 m²) in May and July (2002 and 2003). Arthropods were sampled in the same locations using D-Vac suction sampling (May, June, July), sweep netting (May, June) and pitfall traps open for 7 days (June). This study was part of the same replicated, controlled study (SAFFIE – Sustainable Arable Farming For an Improved Environment) as (Morris et al. 2004, Ogilvy et al. 2006, Smith et al. 2009).
A replicated, controlled study from April-August in 2002 and 2003 on 10 sites in northern and eastern England (Smith et al. 2009) found that invertebrate abundance in wide-spaced row fields was not significantly different from conventional (control) winter wheat fields. In 2002, wide-spaced row fields contained an average of 6.0 invertebrate species/pitfall trap compared to 6.4 in control fields. Both grass and broadleaved vegetation cover had a negative relationship with wide-spaced row fields. There were no significant differences in skylark Alauda arvensis faecal content between nestlings in treatment or control fields. The authors suggest that the value of wide-spaced row fields for skylarks lies in increased access to other food resources. There were three treatments at each site: wide-spaced rows sown at double the normal width (25 cm between rows) but with the same seed rate as control fields, control fields (12.5 cm between rows), and undrilled patches (4 x 4 m) with a density of 2 patches/ha. This study was part of the same replicated, controlled study (SAFFIE – Sustainable Arable Farming For an Improved Environment) as (Morris et al. 2004, Ogilvy et al. 2006, Smith & Jones 2007).
- Morris A.J., Holland J.M., Smith B. & Jones N.E. (2004) Sustainable Arable Farming For an Improved Environment (SAFFIE): managing winter wheat sward structure for Skylarks Alauda arvensis. Ibis, 146, s155-162
- Ogilvy S.E., Clarke J.H., Wiltshire J.J.J., Harris D., Morris A. & Jones N. (2006) SAFFIE - research into practice and policy. Proceedings of the HGCA Conference, Arable crop protection in the balance: Profit and the environment, 14.1-14.12.
- Jones N.E. & Smith B. (2007) Effects of selective herbicide treatment, row width and spring cultivation on weed and arthropod communities in winter wheat. Aspects of Applied Biology, 81, 39-46
- Smith B. & Jones N.E. (2007) Effects of manipulating crop architecture on weed and arthropod diversity in winter wheat. Aspects of Applied Biology, 81, 31-38
- Smith B., Holland J., Jones N., Moreby S., Morris A.J. & Southway S. (2009) Enhancing invertebrate food resources for skylarks in cereal ecosystems: how useful are in-crop agri-environment scheme management options? Journal of Applied Ecology, 46, 692-702