Short-term soil physical responses to grazing and cover crops in an integrated crop-livestock agroecosystem

Abstract

Cover crops (CCs) and grazing play critical roles in the successful implementation of integrated crop-livestock systems (ICLSs) because they can have a direct impact on soil functions. The present study was conducted to assess the short-term impacts of CCs and grazing on soil physical and hydrological properties. Two sites (Northern-Brookings and Northwestern-Brookings) were established in 2016 and 2017, respectively, in South Dakota, United States. The specific objective was to evaluate the impact of CCs and grazed CCs under oat (Avena sativa L.)/CCs–corn (Zea mays L.) rotation on soil physical and hydrological properties. Study treatments included (1) legume-dominated CC (LdC), (2) cattle-grazed LdC (LdC+G), (3) grass-dominated CC (GdC), (4) cattle-grazed GdC (GdC+G), and (5) no CC and no grazing (NC). After two to three years of management, CCs and grazing did not impact soil organic carbon (SOC) and total nitrogen (TN) stocks, and their values at approximate depth of 0 to 20 cm ranged from 50.9 to 60.6 Mg C ha⁻¹ and 3.65 to 4.92 Mg N ha⁻¹, respectively, among the treatments at each site. Cover crops decreased soil bulk density (ρ_b) at 0 to 10 cm and 10 to 20 cm depths and, in general, increased soil water retention (SWR), total porosity, and quasi-steady infiltration rate (Northern-Brookings only) compared to the NC. Cattle grazing of CC generally increased ρ_b and reduced SWR and porosity compared with the ungrazed CC but not to the often-perceived detrimental levels. Our findings showed that CCs can improve some aspects of soil physical health in the short term and that grazing of CCs and crop residue did not cause substantial physical damage to the soil under the conditions of these experiments.