Now showing 1 - 3 of 3
  • Publication
    Impact of field headlands on wheat and barley performance in a cool Atlantic climate as assessed in 40 Irish tillage fields
    The reduction in cereal crop yields on field headlands has previously been examined in other geographical regions, with research focusing on the relationship between yield and the distance from the crop edge. Headlands are subject to greater machinery trafficking than the centre of the field and the level of traffic imposed depends on the machine size and adopted turning practice. The aim of this work was to examine the impact of turning headlands on crop performance in a survey of 40 field sites in Irish conditions. The headland was categorised into three distinct zones: the area next to the field edge subject to moderate traffic intensities (field edge); the main headland area of greatest turning traffic (turning) and a transition zone (transition). An in-field zone (in-field) in which no machinery turns occur was also included. The 2-year survey included sites from three regions, four soil texture classes and had crops established with plough-based systems. Crop measurements, including plant densities, shoot counts and light interception, and yields were recorded at each site and included winter barley (WB), spring barley (SB) and winter wheat (WW) crops. The yield response of each crop type varied with sample zone, region and soil texture. There were significant (P < 0.001) yield differences recorded between the turning area and in-field zone for all three crops. Winter barley yields were reduced by 1.3 t/ha in the turning zone compared with the in-field section, while SB and WW had yield reductions of 2.08 and 4.04 t/ha, respectively, between these two field zones.
    Scopus© Citations 3  78
  • Publication
    Assessment of nitrous oxide emission factors for arable and grassland ecosystems
    We quantified seasonal nitrous oxide (N2O) emissions and the associated emission factors (EFs) from: (i) winter oilseed rape (WOSR) cultivated under conventional tillage (CT) and strip tillage (ST) at four fertilizer rates (0, 160, 240 and 320 kg N ha−1) in 2014/2015, and (ii) grassland plots receiving no fertilizer (0 kg N ha−1), or mineral nitrogen (67 kg N ha−1), and either cattle or pig slurry (50, 100 and 200 m3 ha−1). Greater fluxes were observed at higher soil temperatures and a higher water filled pore space, suggesting that denitrification was the main source of N2O-N from the applied fertilizer/slurry. For WOSR, the N2O EFs ranged from 0.03 to 1.20% with no effect of the cultivation practice on EFs for equal rates of nitrogen fertilizer. Lower EF values were linked to differences in plant growth at individual sites rather than a specific management effect. For the grassland, the N2O EFs were highly variable, ranging from −0.70 to 0.49%, but were generally the highest in treatments receiving the highest concentrations of slurry. The EF values for WOSR illustrates that the Tier 1 approach for calculating EFs may be inadequate and the identification of site-specific effects can aid in refining N2O EF inventories. For the grassland plots all the EFs were significantly lower than the IPCC default values. Although the reason(s) for the low EFs with slurry amendments on grassland is not known, ammonia volatilization could decrease the pool of inorganic N that is available to nitrifying bacteria thereby lowering N2O fluxes.
      188Scopus© Citations 7
  • Publication
    Greenhouse Gas Emissions and Crop Yields From Winter Oilseed Rape Cropping Systems are Unaffected by Management Practices
    Winter oilseed rape is traditionally established via plough-based soil cultivation and conventional sowing methods. Whilst there is potential to adopt lower cost, and less intensive establishment systems, the impact of these on greenhouse gas emissions have not been evaluated. To address this, field experiments were conducted in 2014/2015 and 2015/2016 to investigate the effects of 1) crop establishment method and 2) sowing method on soil greenhouse gas emissions from a winter oilseed rape crop grown in Ireland. Soil carbon dioxide, nitrous oxide and methane emission measurements were carried out using the static chamber method. Yield (t seed ha−1) and the yield-scaled global warming potential (kg CO2-eq. kg−1 seed) were also determined for each management practice. During crop establishment, conventional tillage induced an initially rapid loss of carbon dioxide (2.34 g C m−2 hr−1) compared to strip tillage (0.94 g C m−2 hr−1) or minimum tillage (0.16 g C m−2 hr−1) (p < 0.05), although this decreased to background values within a few hours. In the crop establishment trial, the cumulative greenhouse gas emissions were, apart from methane, unaffected by tillage management when sown at a conventional (125 mm) or wide (600 mm) row spacing. In the sowing method trial, cumulative carbon dioxide emissions were also 21% higher when plants were sown at 10 seeds m−2 compared to 60 seeds m−2 (p < 0.05). Row spacing width (125 and 750 mm) and variety (conventional and semi-dwarf) were found to have little effect on greenhouse gas emissions and differences in seed yield between the sowing treatments were small. Overall, management practices had no consistent effect on soil greenhouse gas emissions and modifications in seed yield per plant countered differences in planting density.
      51Scopus© Citations 8