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Context Labile soil C and N fractions are strongly influenced by agricultural management practices. Aims This study was conducted on three long-term (≥30 years) on-farm sites (sites 1–3), and one short-term (3 years) experimental site (site 4) to evaluate the impacts of integrated crop–livestock system (ICLS) on labile C and N fractions and β-glucosidase enzyme activity for the 0–5 cm soil depth. Methods Long-term management systems (ICLS, corn (Zea mays L.)/grazing–soybean (Glycine max (L.) Merr.)/grazing–cover crop/grazing), control (CNT, corn–soybean with no cover crop and no grazing), and a grazed pasture (GP) at sites 1–3 were compared. At site 4, the treatments included: ICLS (corn/grazing–soybean/grazing–oat (Avena sativa L.)–cover crop/grazing); CC (corn–soybean–oat–cover crop with no grazing); CNT (corn–soybean–oat–fallow with no grazing); and GP. Key results ICLS had higher hot water extractable organic carbon (HWC), cold water extractable organic carbon (CWC), microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), potential carbon mineralisation (PCM) and potassium permanganate oxidisable carbon (POXC) than CNT under long-term management system. Long-term ICLS also enhanced β-glucosidase activity compared to CNT. ICLS had 72%, 214% and 60% higher glucosidase activity than the CNT at sites 1, 2 and 3, respectively. However, the C and N fractions and β-glucosidase activity were not affected by short-term ICLS (site 4). GP always had higher C and N fractions than ICLS and the CNT. There was a significantly positive relationship between SOC and labile C and N fractions, except POXC. Conclusions and implications Long-term inclusion of cover crops and livestock grazing in corn–soybean system was effective in enhancing labile soil C and N fractions.

Agricultural management practices tend to influence soil structure stabilization, mediating many physical, chemical, and biological processes in soils. Therefore, understanding the long‐term effects of management practices on various soil health indicators is crucial to develop sustainable agricultural practices. This study aimed to assess the long‐term conventional and conservation tillage effects on soil physical (aggregates) and biochemical (soil organic carbon [SOC], enzymes, and microbial biomass) parameters under a range of tillage practices in a corn–soybean rotation in Nebraska. The experiment was conducted at two locations as follows: (1) Concord site (36 years) with the three treatments: no‐till (NT), disk, and moldboard plow; and (2) Lincoln site (40 years) with four tillage treatments: NT, double disk, chisel, and moldboard plow. Results showed that NT at both sites significantly increased SOC concentration by 24%–66% compared to moldboard plow. Similarly, double disk tillage increased SOC by 54% compared to the moldboard plow at the Lincoln site. Arylsulfatase, β‐glucosidase, hot‐ and cold‐water extractable carbon, microbial biomass carbon, and nitrogen concentrations significantly decreased with the increased tillage intensity at both sites. This implies that the NT increased these parameters compared to the disk and moldboard plow. However, aggregate size fraction 0.053–0.25 mm was the only parameter higher under moldboard plow (20.8%) than NT. Overall, the results from these long‐term studies indicate that NT, and to a lesser extent the reduced tillage practice of disk till, can improve soil health more than conventional tillage practices under a corn–soybean cropping system, suggesting the adoption of sustainable agricultural practices to improve soil health.

Dedicated bioenergy crops such as switchgrass (Panicum virgatum L.) can be grown on marginally productive lands and positively influence soil properties. However, nitrogen management, and landscape can alter soil structural attributes under bioenergy crop production. This study investigated the impacts of long-term nitrogen fertilization (0-N, 0 kg N/ha; 56-N, 56 kg N/ha and 112-N, 112 kg N/ha) and landscape positions (shoulder and footslope) on soil organic carbon (SOC) and structural attributes under switchgrass production. The 112-N rate enhanced the proportion of 2–4 mm water-stable aggregates by 49%, aggregate associated carbon in 2–4 mm and >4 mm aggregates by 16 and 24%, respectively, aggregate associated nitrogen in >4 mm aggregates by 33% and reduced soil bulk density by 19% compared to the 0-N rate. Footslope position increased the proportion of 2–4 mm water-stable aggregates by 26% and lowered bulk density by 8% compared to the shoulder position. Results showed a significant N-rate × landscape position interaction on SOC and glomalin related soil protein content in bulk soil. Overall, this study showed that nitrogen application to switchgrass planted at footslope on a marginally yielding cropland improved soil structure and physical conditions.