Late sowing of cover crops reduces potential for nitrate leaching reduction and carbon inputs

TY - JOUR

T1 - Late sowing of cover crops reduces potential for nitrate leaching reduction and carbon inputs

AU - Kumar, Uttam

AU - Engedal, Tine

AU - Hansen, Veronika

AU - Gislum, René

AU - Munkholm, Lars J.

AU - Thomsen, Ingrid K.

AU - Larsen, Søren Ugilt

AU - Hansen, Elly Møller

PY - 2025/11/1

Y1 - 2025/11/1

N2 - Good establishment of cover crops early after harvest of the main crop is challenging and requires optimized sowing time to maximize ecosystem services in Northwestern Europe. We quantified the abilities of three cover crop species, fodder radish (Raphanus sativus), oats (Avena sativa), and phacelia (Phacelia tanacetifolia) to (i) take up nitrogen (N), reduce nitrate leaching when sown at four sowing times from 10 Aug to 7 Sep at two sandy loam sites in Denmark (Foulum and Flakkebjerg) during two percolation periods of 2022–23 and 2023–24, and (ii) provide carbon (C) input to the soil at two sowing times at Flakkebjerg in 2023. N uptake and nitrate leaching reduction declined with delayed sowing time. The decline followed different patterns for N uptake and nitrate leaching reduction and varied depending on interactions between species, percolation period, and site. Each day of delayed sowing from 10 Aug to 7 Sep decreased the ability of cover crops to reduce nitrate leaching by 0.5 kg N ha⁻¹ day⁻¹ at Flakkebjerg and 1.2 kg N ha⁻¹ day⁻¹ at Foulum. Overall, fodder radish and phacelia more efficiently reduced leaching at the early sowing times, while fodder radish was most effective at the later sowing times. At Flakkebjerg in 2023, fodder radish accumulated more C than oats and phacelia when sown on 10 Aug. Delaying sowing to 30 Aug reduced total C input from all cover crops by 60 %. These findings can potentially be used for enhancing environmental and climate benefits of cover crops in sustainable cropping system design.

AB - Good establishment of cover crops early after harvest of the main crop is challenging and requires optimized sowing time to maximize ecosystem services in Northwestern Europe. We quantified the abilities of three cover crop species, fodder radish (Raphanus sativus), oats (Avena sativa), and phacelia (Phacelia tanacetifolia) to (i) take up nitrogen (N), reduce nitrate leaching when sown at four sowing times from 10 Aug to 7 Sep at two sandy loam sites in Denmark (Foulum and Flakkebjerg) during two percolation periods of 2022–23 and 2023–24, and (ii) provide carbon (C) input to the soil at two sowing times at Flakkebjerg in 2023. N uptake and nitrate leaching reduction declined with delayed sowing time. The decline followed different patterns for N uptake and nitrate leaching reduction and varied depending on interactions between species, percolation period, and site. Each day of delayed sowing from 10 Aug to 7 Sep decreased the ability of cover crops to reduce nitrate leaching by 0.5 kg N ha⁻¹ day⁻¹ at Flakkebjerg and 1.2 kg N ha⁻¹ day⁻¹ at Foulum. Overall, fodder radish and phacelia more efficiently reduced leaching at the early sowing times, while fodder radish was most effective at the later sowing times. At Flakkebjerg in 2023, fodder radish accumulated more C than oats and phacelia when sown on 10 Aug. Delaying sowing to 30 Aug reduced total C input from all cover crops by 60 %. These findings can potentially be used for enhancing environmental and climate benefits of cover crops in sustainable cropping system design.

KW - Catch crop

KW - Growth characteristics

KW - Percolation period

KW - Soil organic carbon

KW - Sowing time

KW - Sustainability

UR - https://www.scopus.com/pages/publications/105010522319

U2 - 10.1016/j.agee.2025.109858

DO - 10.1016/j.agee.2025.109858

M3 - Journal article

AN - SCOPUS:105010522319

SN - 0167-8809

VL - 393

JO - Agriculture, Ecosystems and Environment

JF - Agriculture, Ecosystems and Environment

M1 - 109858

ER -