3 research outputs found
No-Till Mitigates SOC Losses after Grassland Renovation and Conversion to Silage Maize
Many studies recommend no-till (NT) to increase soil organic carbon (SOC) in the topsoil (<30 cm) of arable land to counterbalance greenhouse gas emissions. Its potential use to mitigate SOC losses during conversion and renovation of grassland ecosystems in the top meter soil is yet to be determined. The SOC dynamics of a 10-year-old grassland converted to silage maize (CM) and renovated and seeded (GR) using either conventional tillage (CT) or NT were compared to an undisturbed grassland control (GC) for 7 years, across three fixed soil depth increments (0â30, 30â60, 60â90 cm). The annual C inputs (Cinput) from crop residues were further analyzed. The systems were either non-fertilized (N0) or fertilized with mineral N (N1) according to a demand of 180 and 380 kg N haâ1 yearâ1 in the silage maize and grassland systems, respectively. For the 7-year period, the renovated grassland using NT ensured maintenance of the initial SOC in the topsoil, while a conversion toward arable cropping resulted in SOC losses, regardless of the tillage method. The use of NT during conversion significantly reduced these losses from 2.5 Mg haâ1 yearâ1 to 1.8 Mg haâ1 yearâ1, for a 28% reduction compared to CT. In the subsoil (30â90 cm), SOC remained stable and was not affected by the cropping systems nor by the tillage method. Reduced annual Cinput was found as the main factor affecting SOC losses after grassland removal, regardless of the tillage method. Our findings highlight the potential of NT to mitigate annual SOC losses after grassland conversion if annual Cinput remains high
No-Till Mitigates SOC Losses after Grassland Renovation and Conversion to Silage Maize
Many studies recommend no-till (NT) to increase soil organic carbon (SOC) in the topsoil (<30 cm) of arable land to counterbalance greenhouse gas emissions. Its potential use to mitigate SOC losses during conversion and renovation of grassland ecosystems in the top meter soil is yet to be determined. The SOC dynamics of a 10-year-old grassland converted to silage maize (CM) and renovated and seeded (GR) using either conventional tillage (CT) or NT were compared to an undisturbed grassland control (GC) for 7 years, across three fixed soil depth increments (0–30, 30–60, 60–90 cm). The annual C inputs (Cinput) from crop residues were further analyzed. The systems were either non-fertilized (N0) or fertilized with mineral N (N1) according to a demand of 180 and 380 kg N ha−1 year−1 in the silage maize and grassland systems, respectively. For the 7-year period, the renovated grassland using NT ensured maintenance of the initial SOC in the topsoil, while a conversion toward arable cropping resulted in SOC losses, regardless of the tillage method. The use of NT during conversion significantly reduced these losses from 2.5 Mg ha−1 year−1 to 1.8 Mg ha−1 year−1, for a 28% reduction compared to CT. In the subsoil (30–90 cm), SOC remained stable and was not affected by the cropping systems nor by the tillage method. Reduced annual Cinput was found as the main factor affecting SOC losses after grassland removal, regardless of the tillage method. Our findings highlight the potential of NT to mitigate annual SOC losses after grassland conversion if annual Cinput remains high
Integrating Crop-Livestock System Practices in Forage and Grain-Based Rotations in Northern Germany : Potentials for Soil Carbon Sequestration
Integrating leys, cover crops, and animal manures constitute promising avenues to reach annual soil organic carbon changes (ÎSOC) >0.4% in forage and grain-based crop rotations, rates required to offset the increasing C emissions from fossil fuels (â4 per milleâ initiative). How these practices and rotations perform in reaching this aim was object of analysis in this paper. Five cropping systems (CS), including three three-year forage and grain-based crop rotations containing annual grass-clover leys (FR and MR) or cover crops (GR), and two contrasting controls (continuous silage maize (CM), and permanent grassland (PG)) were compared for their impact on SOC stocks over eight years (2010â2018). The CS were unfertilized (N0) or fertilized using cattle slurry (N1) at a rate of 240 kg N ha-1 yr-1 applied in the non-leguminous crops. The ÎSOC of the top 30 cm soil layer and the annual carbon inputs (Cin) from slurry applications and plant residues were estimated, their relationship established, and the slurry-induced C retention coefficient was determined. The FR and MR SOC stocks remained stable at N1, while the GR and CM SOC decreased over time by tendency even at N1. Only the PG reached ÎSOC >0.4%. Differences in ÎSOC between CS and N rates were highly associated with the system-specific increase in belowground Cin, induced by slurry applications. Slurry-induced C retention coefficients differed strongly between CS: CM (3%) followed by GR (12%), and by FR and MR (20â15%), and lastly by PG (24%). Promoting below-ground carbon inputs was identified as an efficient way to reach significant increases in ÎSOC. We conclude that a ley in only one out of three years is not sufficient to significantly increase SOC stocks in arable crop rotations of the study region