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Soil organic matter is assumed to accumulate with conservation management. Onfarm surveys using paired-farm and chronosequence approaches could validate assumptions, as well as provide a diversity of soils and management conditions to assess organic matter fractions. The objective of this study was to assess how land use and pasture management affected the gradient of organic matter fractions from active to resistant. Particulate and non-particulate (also called mineral-associated) organic C and N fractions were isolated and soil-test biological activity was measured from 304 profiles at 0- to 10-, 10- to 30-, and 30- to 60-cm depths on 31 private farms in Virginia. Root-zone enrichment contents of these soil properties were calculated following subtraction of a baseline from total stocks of each soil profile. Land use was a key factor affecting root-zone enrichment (0- to 30-cm depth) of particulate organic C (Mg C ha−1) (p ≤ 0.05): conventional-till cropland (6.3) = no-till cropland (9.2) < grassland (14.2) < woodland (16.7). Root-zone enrichments of soil C and N fractions increased with pasture age to a plateau achieved by 25 years and were optimized at cattle stocking rate of 1.0 ± 0.2 Mg live weight ha−1. Feeding hay increased root-zone enrichment of soil-test biological activity (49 kg CO2-C 3 day−1 [Mg hay]−1). Although non-particulate organic C and N dominated, accumulation with time and steady-state concentration of particulate fractions were vital steps toward greater soil organic matter under conservation management. Root-zone enrichment calculations from on-farm sampling were helpful in distinguishing true effects of management from pedogenesis on soil organic matter formation. [ABSTRACT FROM AUTHOR]

Current fertilizer recommendations often neglect nutrient cycling across crop rotations. This study aimed to assess the decay rate and nutrient (N, P, K) release patterns of sorghum, black oat, and corn residues (omitido) in an integrated crop–livestock system. The experiment used factorial treatments based on two sward heights (high and low) and two nitrogen fertilization levels (N-pasture at 200 kg N ha−1 and N-corn at 0 kg N ha−1). Litter bags were collected at various intervals from each crop to measure nutrient release patterns and decomposition rates. The results showed that pasture height and nitrogen fertilization significantly influenced decomposition and nutrient release, affecting the subsequent grain crop phase. Potassium was released rapidly and in high amounts. Nitrogen fertilization during the pasture phase prevented nitrogen and phosphorus immobilization in black oat residue and reduced immobilization in corn residue. These findings highlight the importance of accounting for nutrient cycling and decomposition rates in fertilization strategies to enhance the sustainability of integrated crop–livestock systems. [ABSTRACT FROM AUTHOR]

Contemporary agricultural systems can be generalized as highly specialized operations that are fueled by mechanization; supplied with external nutrients to maximize production; crops protected by petrochemicals to fight against weed, disease, and insect pressures; and livestock protected by therapeutics to ward off virus and bacterial infections when managed in confinement. Such specialized systems have led to low levels of diversity, elevated environmental risks from contamination, loss of soil organic matter, ecological instability, and limited adaptability to climate change. More diversified farming systems are possible, but research required to characterize them in a holistic manner as an alternative to contemporary, specialized systems remains challenging to fund and sustain over time, primarily because they require more labor, management skills, and accessible markets to achieve additional ecological, environmental, and social goals. We share some perspectives as to (1) how specialized systems became the norm and (2) what changes could be made to reverse some ecological risks and environmental declines associated with specialization, acknowledging there is no panacea. Strong evidence exists for perennial forages to restore soil organic carbon (C) and nitrogen, but system‐level analyses of the net balance in greenhouse gas emissions remain to be characterized in the myriad of potential integrated crop–livestock systems that might be deployed across the diversity of edaphic, environmental, and socio‐economic conditions. We suggest there are abundant opportunities for more sustainable agricultural production to sequester soil organic C, reduce greenhouse gas emissions, and develop more climate‐resilient agricultural systems that will be needed in a future dominated by climate change issues. Core Ideas: Forage‐based crop rotations are a proven practice for conserving nutrients and improving soil health.Diversity on farms in the United States is low and could be enhanced with integrated crop–livestock systems.Structural barriers to integrated crop–livestock systems are present but could be overcome. [ABSTRACT FROM AUTHOR]

Background: Soil organic C and N data from privately managed pastures in the southeastern United States are relatively scant. Methods: A paired‐farm approach was deployed to determine how a variety of soil health parameters related to nutrient and water cycling might be altered under grazed, botanically diverse perennial pastures compared with annual monoculture croplands in three Major Land Resource Areas of the southeastern United States. Results: Soil stability index averaged 0.64 and 0.91 mm mm−1 under cropland and grazed pasture, respectively, suggesting that pastures had a more stable soil surface that was resistant to erosion and allowed rapid water infiltration. Surface‐soil organic C and N fractions (i.e., total, particulate, and mineralizable fractions at 0–10 cm depth) were greater under pasture than under cropland. Across locations, root‐zone enrichments (0–30 cm depth) of organic C and N fractions were greater under pasture than under cropland. Within locations, root‐zone enrichment of total soil N was greater (p < 0.05) under pasture than under cropland in the Blue Ridge (2.87 vs. 1.10 Mg N ha−1, respectively) and the Piedmont (2.80 vs. 2.10 Mg N ha−1), but not in the Blackland Prairie (2.40 vs. 2.12 Mg N ha−1). Conclusions: This study provides evidence that rotationally grazed, perennial grasslands can store more soil organic C and N and improve soil surface stability conditions compared with neighboring croplands producing commodity feed grains for feedlot finishing. [ABSTRACT FROM AUTHOR]