@article{bortolli_assmann_bortolli_maccari_bernardon_jamhour_franzluebbers_soares_severo_2024, title={Nutrient Dynamics in Integrated Crop-Livestock Systems: Effects of Stocking Rates and Nitrogen System Fertilization on Litter Decomposition and Release}, volume={14}, ISSN={["2073-4395"]}, DOI={10.3390/agronomy14092009}, abstractNote={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.}, number={9}, journal={AGRONOMY-BASEL}, author={Bortolli, Marcos Antonio and Assmann, Tangriani Simioni and Bortolli, Betania Brum and Maccari, Marcieli and Bernardon, Angela and Jamhour, Jorge and Franzluebbers, Alan J. and Soares, Andre Brugnara and Severo, Igor Kieling}, year={2024}, month={Sep} }
 @article{franzluebbers_shoemaker_cline_lipscomb_stafford_farmaha_waring_lowder_thomason_poore_2022, title={Adjusting the N fertilizer factor based on soil health as indicated by soil-test biological activity}, volume={7}, ISSN={["2471-9625"]}, DOI={10.1002/ael2.20091}, abstractNote={AbstractAgriculture faces a dilemma with nitrogen (N)—it is often the most necessary external input to optimize production, several generations of farmers became accustomed to its relatively inexpensive cost, and it contributes to widespread pollution due to numerous loss pathways to the environment. However, standard N fertilizer recommendations have not accounted well enough for a key source via mineralizable soil N. Soil‐test biological activity (STBA) is strongly associated with mineralizable soil N, both of which become surface‐enriched with conservation agricultural management using soil health principles. A series of field experiments assessed the contribution of mineralizable soil N to the N supply needed to optimize corn (Zea mays L.) grain and fall‐stockpiled tall fescue [Schedonorus arundinaceus (Schreb.) Dumort.] production. This essay synthesizes how STBA along with cost‐to‐value threshold can be used to modify the N fertilizer factor to optimize economic return and avoid environmental degradation.}, number={2}, journal={AGRICULTURAL & ENVIRONMENTAL LETTERS}, author={Franzluebbers, Alan J. and Shoemaker, Robert and Cline, Jeff and Lipscomb, Bruce and Stafford, Carl and Farmaha, Bhupinder S. and Waring, Robert and Lowder, Nathan and Thomason, Wade E. and Poore, Matt H.}, year={2022} }
 @article{leon_creamer_reberg-horton_franzluebbers_2022, title={Eradication of Commelina benghalensis in a long-term experiment using a multistakeholder governance model: a case of regulatory concerns defeating ecological management success}, volume={15}, ISSN={["1939-747X"]}, url={https://doi.org/10.1017/inp.2022.23}, DOI={10.1017/inp.2022.23}, abstractNote={AbstractTropical spiderwort (Commelina benghalensis L.) is a noxious invasive species and was detected in a long-term experiment in a research farm in Goldsboro, NC. A multistakeholder governance model was used to address the invasion of this species. Regulators insisted on the use of fumigation in all fields, but after intense negotiations, a multi-tier eradication plan was designed and implemented, allowing fumigation outside the long-term experiment and a combination of integrated approaches (including physical removal) and intense monitoring and mapping for long-term experimental fields. In the long-term experiment, C. benghalensis populations decreased logarithmically from more than 50,000 plants in approximately 80 ha in 2005 to 19 plants in less than 1 ha in 2019, with a projection of full eradication by 2024. Despite these results, which were considered to be proof of successful ecological management by university researchers, regulators decided to fumigate the fields containing the remaining 19 plants. This decision was made because regulators considered factors such as professional liability and control efficacy. This created serious disagreements between the different stakeholders who participated in the design of the original plan. Despite the goodwill all parties exhibited at the beginning of the governance process, there were important shortcomings that likely contributed to the disagreements at the end. For example, the plan did not include specific milestones, and there was no clarity about what acceptable progress was based on (i.e., plant numbers or the rate of population decline). Also, no financial limits were established, which made administrators concerned about the financial burden the eradication program had become over time. Multistakeholder governance can effectively address plant invasions, but proper definition of progress and the point at which the program must be modified are critical for success, and all this must be done within a governance model that balances power in the decision-making process.}, number={3}, journal={INVASIVE PLANT SCIENCE AND MANAGEMENT}, author={Leon, Ramon G. and Creamer, Nancy and Reberg-Horton, S. Chris and Franzluebbers, Alan J.}, year={2022}, month={Sep}, pages={152–159} }
 @article{franzluebbers_poore_2022, title={Soil fertility characteristics in North Carolina pastures as affected by spatial separation and renovation with annual forages}, ISSN={["1435-0645"]}, DOI={10.1002/agj2.21218}, abstractNote={AbstractSpatial variation in soil properties is often considered significant across broad geographical regions due to soil formation factors. However, fine‐scale variations might also be significant. This study was conducted with the original intent of assessing how simple and complex mixtures of annual forages might be used to renovate perennial pastures. Private farmers in the Flatwoods, Piedmont, and Blue Ridge Major Land Resource Areas of North Carolina tested annual forages to renovate tall fescue pastures. Soil was sampled in multiple random locations in each field at depths of 0–6, 6–12, and 12–20 cm at the beginning and ending of a 3‐yr annual forage evaluation. Relative variation among five components (year of sampling [n = 2], physiographic region [n = 3], annual forage treatment [n = 2], soil depth [n = 3], and random variation from pseudoreplicates [n = 3 in 2015 and n = 5 in 2018]) was assessed for four soil physical, 10 soil biological, and 16 soil chemical properties. Soil chemical properties were mostly affected by physiographic region (47 ± 26% of total variation) and soil depth (33 ± 18%), soil biological properties were mostly affected by soil depth (63 ± 25%) and random pseudoreplication (14 ± 6%), and soil physical properties were equally affected by pseudoreplication (35 ± 21%), physiographic region (32 ± 18%), and soil depth (29 ± 22%). The type of annual forage had no discernible effect on soil properties, even the most biologically active. A diversity of spatial variations was important, suggesting that regional‐level ecological investigations require careful attention to an appropriate sampling design considering multiple factors.}, journal={AGRONOMY JOURNAL}, author={Franzluebbers, Alan. J. and Poore, Matt H.}, year={2022}, month={Dec} }
 @article{franzluebbers_broome_pritchett_wagger_lowder_woodruff_lovejoy_2021, title={Multispecies cover cropping promotes soil health in no-tillage cropping systems of North Carolina}, volume={76}, ISSN={["1941-3300"]}, DOI={10.2489/jswc.2021.00087}, abstractNote={Moving agricultural production systems toward a greater level of soil health is needed for sustainability. Conservation agricultural systems utilizing no or minimum tillage are an important step forward, but enhancing carbon (C) inputs with diverse cover crops and facilitating biologically active nitrogen (N) cycling are also needed. Summer cash-crop systems, particularly in the warm-humid region of the southeastern United States, may benefit from multispecies winter cover cropping if sufficient biomass were produced. We implemented a research and demonstration project utilizing multispecies cover cropping in 15 counties of North Carolina during 2015 to 2019 to assess biomass production and its effect on surface-soil properties. Winter cover crop biomass production was variable among locations, but exceeded 3,790 kg ha–1 in one-third of trials. Nitrogen contained in aboveground cover crop biomass exceeded 60 kg ha–1 in the upper third of trials. Of 30 soil properties measured in each site-year (n = 31) at depths of 0 to 5 and 5 to 15 cm, soil-test biological activity, C mineralization during 24 days, total soil N, and Mehlich-III phosphorus (P) and potassium (K) were most consistently affected when comparing multispecies cover cropping with either no or single-species cover cropping. Despite relatively short duration of evaluations (i.e., mostly one to two years), we were able to elucidate that winter multispecies cover cropping has potential to improve soil health conditions in the region. Soil-test biological activity demonstrated the living nature of soil and was sensitive to conservation agricultural management. The support of a hands-on farmer and adviser network encouraged success.}, number={3}, journal={JOURNAL OF SOIL AND WATER CONSERVATION}, author={Franzluebbers, A. J. and Broome, S. W. and Pritchett, K. L. and Wagger, M. G. and Lowder, N. and Woodruff, S. and Lovejoy, M.}, year={2021}, pages={263–275} }
 @article{maccari_assmann_bernardon_soares_franzluebbers_bortolli_bortolli_glienke_2021, title={Relationships between N, P, and K in corn biomass for assessing the carryover effects of winter pasture to corn}, volume={129}, ISSN={["1873-7331"]}, DOI={10.1016/j.eja.2021.126317}, abstractNote={Pasture fertilization may influence the subsequent corn crop in integrated crop-livestock systems, but few tools exist to assess the likelihood and magnitude of this carryover effect. Our goals were to determine whether a previous pasture with N fertilization could supply adequate N nutrition to a succeeding corn crop and affect its P and K nutrition using the concept of N dilution curve and relationships between N, P, and K in corn shoot biomass. The experiment consisted in a winter grazed pasture followed by a corn crop in summer. Treatments were N fertilization of a black oat (Avena strigosa) winter pasture (0 and 200 kg N ha−1) as main plots and four sidedress N fertilization rates (0, 100, 200, and 300 kg N ha−1) applied to corn as sub-plots in a randomized complete block design with split-plot restriction. The N nutrition index, that is, the ratio of observed shoot N concentrations to critical N concentration determined by a critical N dilution curve, adequately identified situations of deficient N nutrition in corn following a pasture with or without N fertilization. This carryover effect from a winter pasture should therefore be accounted for in N fertilizer recommendations for corn in tropical soils. Corn P nutrition, based on critical P concentrations derived as a function of N concentration, was nearly optimal when no N was applied to the pasture, but it was less than optimal when N was applied. Although no critical K curves have been published, our results confirm that the relationship between shoot K and N concentrations varies with the level of N nutrition as does the relationship between shoot P and N concentrations. Our results confirm that the concept of critical N and P concentrations serves as a useful reference to assess the status of N and P nutrition during corn growth in tropical soils with the potential to improve nutrient management of corn following a pasture in an integrated crop-livestock system.}, journal={EUROPEAN JOURNAL OF AGRONOMY}, author={Maccari, Marcieli and Assmann, Tangriani Simioni and Bernardon, Angela and Soares, Andre Brugnara and Franzluebbers, Alan and Bortolli, Marcos and Bortolli, Betania Brum and Glienke, Carine Lisete}, year={2021}, month={Sep} }
 @article{rigon_calonego_capuani_franzluebbers_2021, title={Soil organic C affected by dry-season management of no-till soybean crop rotations in the tropics}, volume={462}, ISSN={["1573-5036"]}, DOI={10.1007/s11104-021-04878-0}, number={1-2}, journal={PLANT AND SOIL}, author={Rigon, Joao Paulo Gonsiorkiewicz and Calonego, Juliano Carlos and Capuani, Silvia and Franzluebbers, Alan J.}, year={2021}, month={May}, pages={577–590} }
 @article{franzluebbers_wendroth_creamer_feng_2020, title={Focusing the future of farming on agroecology}, volume={5}, ISSN={["2471-9625"]}, DOI={10.1002/ael2.20034}, abstractNote={AbstractThe future of humanity and how agriculture can continue to support the food and fiber needs of a burgeoning population are threatened by agriculture's persistent negative effects on the environment. Essential natural resources that will be needed in increasingly greater capacity are being undermined by agricultural practices that continue to deplete the soil resource base, pollute freshwater and coastal estuaries needed for life support, reduce habitat to support biodiversity, and emit harmful greenhouse gases that compromise our ability to withstand changes to the climate. Solutions to these problems are available in known and increasingly well documented approaches using agroecological principles that manage food production in harmony with nature, not against it. This commentary provides a message that we should be seeking healing of our planet, not just less harm than in the past. It is an important distinction that needs to be considered for the future health of people and the planet.}, number={1}, journal={AGRICULTURAL & ENVIRONMENTAL LETTERS}, author={Franzluebbers, Alan J. and Wendroth, Ole and Creamer, Nancy G. and Feng, Gary G.}, year={2020} }
 @article{franzluebbers_poore_2021, title={Nutritive value of fall-stockpiled tall fescue pastures on southeastern US farms}, volume={113}, ISSN={["1435-0645"]}, DOI={10.1002/agj2.20517}, abstractNote={AbstractStockpiling of tall fescue [Schedonorus arundinaceus (Schreb.) Dumort.] may be a useful strategy to avoid fescue toxicosis in autumn and to reduce winter hay feeding costs of beef cattle grazing systems. Typical recommendations are to fertilize with N prior to fall growth. However, little information is available on how soil and pasture conditions affect forage nutritive value responses to fall fertilization. We analyzed the nutritive value of fall‐stockpiled forage in response to N fertilization on 92 fields in North Carolina and neighboring states from 2015 to 2018. We hypothesized that inherent soil nutrient cycling might minimize the need for exogenous N fertilizer inputs. Increasing N fertilization led to (a) greater crude protein, macronutrient concentrations (i.e., K, Ca, and P), and relative feed value and (b) lower acid detergent fiber, neutral detergent fiber, and lignin. However, changes were small, and effects were modified by surface soil properties. For example, crude protein increased from an average of 114 g kg–1 without N fertilization to 131 g kg–1 with 100 kg N ha–1, but this significant N fertilization effect diminished with increasing total organic C and inorganic N of a field. Small changes in nutritive value may have been a consequence of trials conducted on well‐managed farms with relatively high soil‐test biological activity and net N mineralization potential. Therefore, a single recommendation for fall N fertilization may not always be appropriate for enhancing nutritive value. Stockpiled tall fescue had sufficient nutritive value for pregnant cows, and N fertilization may not always be necessary.}, number={1}, journal={AGRONOMY JOURNAL}, author={Franzluebbers, Alan J. and Poore, Matt H.}, year={2021}, month={Jan}, pages={610–622} }
 @article{franzluebbers_reberg-horton_creamer_2020, title={Soil carbon and nitrogen fractions after 19 years of farming systems research in the Coastal Plain of North Carolina}, volume={84}, ISSN={["1435-0661"]}, DOI={10.1002/saj2.20072}, abstractNote={AbstractLong‐term agricultural experiments in the Coastal Plain of the southeastern United States are needed to understand biogeochemical processes and design better systems to overcome a changing climate and other perturbations. We determined a suite of soil organic C and N fractions after 19 yr of management from a diverse farming system project in Goldsboro, NC. Soil was collected at 0‐ to 6‐, 6‐ to 12‐, and 12‐ to 20‐cm depth increments from 14 treatments that were subsets of five overarching treatments of conventional cropping, integrated crop–livestock systems, organic cropping, plantation forestry, and old‐field successional land use. Surface residue C and N were greater with woody (i.e. plantation forestry and successional) than with cropping systems (7,491 and 2,896 kg C ha−1, respectively; 138 and 60 kg N ha−1, respectively). Soil‐test biological activity was greater with alternative cropping (i.e. integrated crop–livestock and organic systems) than conventional cropping (314 vs. 220 kg CO2–C ha−1 3 d−1, respectively). An integrated crop–livestock system with grazed pasture in long rotations with crops had greater net N mineralization than hayed forage in shorter rotations (111 vs. 92 kg N ha−1 24 d−1, respectively). Total organic C and particulate organic N concentrations were highly stratified with depth, but stocks were not different between conventional and no‐till cropping when summed to 20 cm. We conclude that alternative cropping systems with forage‐based rotations, limited tillage, and organic inputs can create long‐lasting improvements in soil organic C and N fractions than conventional agricultural and more naturalized systems.}, number={3}, journal={SOIL SCIENCE SOCIETY OF AMERICA JOURNAL}, author={Franzluebbers, Alan J. and Reberg-Horton, S. Chris and Creamer, Nancy G.}, year={2020}, pages={856–876} }
 @article{franzluebbers_poore_freeman_rogers_2021, title={Soil nutrient distribution on cattle farms in three physiographic regions of North Carolina}, volume={113}, ISSN={["1435-0645"]}, DOI={10.1002/agj2.20508}, abstractNote={AbstractBeef cattle production systems are sometimes considered a source of nutrient enrichment due to alteration of botanical composition and excretion of nutrients in isolated zones of pastures. However, research on environmental effects from livestock grazing in the eastern United States has been scant. We conducted an intensive soil sampling campaign on six private farms in three physiographic regions of North Carolina to determine the impacts of landscape features, pasture management, and animal behavior on a suite of soil nutrients. Total and particulate organic C and soil‐test biological activity (STBA) increased with increasing elevation due to edaphic and climate factors. Within farms, fields with different management illustrated that: (a) swine and poultry manure application can favorably enrich soil with infrequent application, but lead to excessive soil‐test P and K with repeated application; (b) positive impacts on total and particulate organic C and STBA occur with grazed perennial forages compared with annual forages and previous cropping; and (c) enrichment of total and particulate organic C and STBA occurs with winter hay feeding, but excessive nutrient accumulation can occur if fed in the same location repeatedly. Aggregated enrichment of soil organic C, STBA, and soil‐test P and K occurred on 30% of fields near drinking water tanks, shade sources, gates, and hay feeding stations. Improved grazing management with rotational stocking and more year‐round grazing helped to minimize occurrence and magnitude of nutrient enrichment zones. We conclude that improved grazing management systems can have positive impacts on the environment, and likely on farm livelihoods.}, number={1}, journal={AGRONOMY JOURNAL}, author={Franzluebbers, Alan J. and Poore, Matt H. and Freeman, Sharon R. and Rogers, Johnny R.}, year={2021}, month={Jan}, pages={590–609} }
 @article{franzluebbers_poore_2020, title={Soil-test biological activity with the flush of CO2: VII. Validating nitrogen needs for fall-stockpiled forage}, volume={112}, ISSN={["1435-0645"]}, DOI={10.1002/agj2.20153}, abstractNote={AbstractNitrogen fertilizer is an expensive input, and its necessity in grazed tall fescue (Schedonorus arundinaceus) pastures can be questioned when sufficient soil N mineralization occurs. A soil‐testing tool that could predict the need for N fertilizer inputs would be beneficial to producers to optimize profit and avoid environmental contamination. Thirty‐seven on‐farm trials were conducted in the Piedmont and Blue Ridge regions of Georgia, South Carolina, North Carolina, and Virginia in 2018 to evaluate fall‐stockpiled tall fescue yield response to N and P fertilizer inputs. Carbon and N characteristics of the soil surface (0‐ to 10‐cm depth) and surface residue varied among sites. Forage mass responses to P fertilizer input were below the economic threshold, regardless of Mehlich‐III extractable P. Forage mass responses to N fertilizer input did not exceed a low cost/value threshold of 5 kg forage kg−1 N in 24 of the trials. Economically optimum N rate was greatest when soil N mineralization and soil‐test biological activity (STBA) were at low levels. Results validated those of an earlier study on 55 fields, and taken together, suggest that N fertilizer for fall‐stockpiled tall fescue could be as high as 80 kg N ha−1 on fields with very low STBA (<100 mg CO2–C kg−1 soil 3 d−1) and declining to nil with medium STBA (>250 mg CO2–C kg−1 soil 3 d−1), depending on cost/value threshold. Healthy soils with high STBA can be managed effectively without N fertilizer inputs to recycle nutrients and promote more sustainable agricultural systems.}, number={3}, journal={AGRONOMY JOURNAL}, author={Franzluebbers, Alan J. and Poore, Matt H.}, year={2020}, pages={2240–2255} }
 @article{castillo_tiezzi_franzluebbers_2020, title={Tree species effects on understory forage productivity and microclimate in a silvopasture of the Southeastern USA}, volume={295}, ISSN={["1873-2305"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85081013835&partnerID=MN8TOARS}, DOI={10.1016/j.agee.2020.106917}, abstractNote={Ecosystem services provided by silvopastoral systems are mediated by specific management practices, environmental conditions, and overall design of the system. We hypothesized that selection of tree species affects understory forage nutritive value and productivity, light/shade environment, and microclimate. The silvopastoral system was located at the Center for Environmental Farming Systems in Goldsboro, North Carolina, USA. Three overstory tree-species were Pinus palustris (PP; longleaf pine), Pinus taeda (PT; lobloblly pine), and Quercus pagoda (QP; cherrybark oak). The understory forage component consisted of a four-way mixture of native warm-season grasses [big bluestem (Andropogon gerardii, ‘Eastern’, KY origin), eastern gamagrass (Tripsacum dactyloides, MO origin), indiangrass (Sorghastrum nutans, ‘NC ecotype’), and switchgrass (Panicum virgatum, ‘Alamo’)]. The experimental design was an RCBD with 3 replicates. There was no effect of seedbed preparation (till versus no-till) on forage establishment. Understory dry matter yield, crude protein and total digestible nutrient concentrations of the harvested forage were not affected by tree species, with the exception at the 3.5 south sampling point. Overstory effects on microclimate variables were not different among tree-species, but were more noticeable during the daytime of the summer months, and were at the most 1-degree point for temperature and temperature-humidity index and 3 points for relative humidity. The silvopasture design in our study provided year-round shade by the tree-component, with varying levels of shade (ranging from 90 to 6% of incident photosynthetic active radiation) due to geographic location, tree species, and season. Our results describe and highlight the potential of trees in a silvopasture design in the southeastern USA to mitigate changes in temperature, humidity, the temperature-humidity index, and forage productivity and as a function of tree species and at different distance from the trees.}, journal={AGRICULTURE ECOSYSTEMS & ENVIRONMENT}, author={Castillo, Miguel S. and Tiezzi, Francesco and Franzluebbers, Alan J.}, year={2020}, month={Jun} }
 @article{poore_rogers_franzluebbers_2019, title={Enhancing production efficiency on southern beef farms with an interactive extension approach using forage management.}, volume={97}, ISSN={["1525-3163"]}, DOI={10.1093/jas/skz053.158}, abstractNote={Abstract
               Production efficiency in beef grazing systems can be improved by several relatively simple changes in forage management practices. During a 4-year project period funded by the NRCS Conservation Innovation Grant Program (68-3A75-14–251) and in collaboration with the University of Georgia, the Amazing Grazing Program in North Carolina utilized several innovative forage management approaches on 6 private farms and 3 public research stations to educate beef producers. On-farm grid sampling illustrated spatial distribution of soil nutrients as influenced by long-term historical management, particularly of winter hay feeding stations. Side-by-side testing of simple and complex annual forage mixes on three private farms demonstrated the opportunities to enhance forage nutritive value, capture the value of diverse botanical composition, and to defer grazing on perennial pastures. Smallplot testing of yield response to fall-stockpiled tall fescue nitrogen fertilizer rate allowed producers to reap the economic benefits of improved soil health and to help improve the environment surrounding their farm. At each private farm, summer, and winter forage management workshops explored innovative approaches to beef farm management, including the nature and importance of dung beetles, value of simple compared with complex annual forages, how to approach winter grazing, benefits of hay unrolling, need for mineral supplementation, utilizing temporary fencing, and frost-seeding clovers. As the project progressed, interest and attendance at workshops grew and cooperating farmer engagement increased. We found that many small-scale beef farmers were interested in simple practices such as hay unrolling and frost seeding when demonstrated by their peers. Using a variety of educational approaches, workshop audiences responded positively to hands-on activities and time for open discussion. Attendees were interested, attentive, and motivated to adopt new practices based on these practical demonstrations on peer farms.}, journal={JOURNAL OF ANIMAL SCIENCE}, author={Poore, Matthew H. and Rogers, Johnny R. and Franzluebbers, Alan J.}, year={2019}, month={Jul}, pages={70–70} }
 @article{franzluebbers_poore_freeman_rogers_2019, title={Soil-surface nutrient distributions in grazed pastures of North Carolina}, volume={74}, ISSN={["1941-3300"]}, DOI={10.2489/jswc.74.6.571}, abstractNote={Soil nutrient distribution in perennial pastures is likely affected by livestock activities, but detailed spatial patterns on a diversity of farms have not been widely investigated. Livestock management variables, such as placement of drinking water sources, fencing, and winter hay-feeding stations, as well as pasture utilization through seasonal stocking, could affect nutrient distribution despite attempts at uniform application of fertilizers. We sampled perennial pasture portions of three research station farms in North Carolina on a 40 m grid in 2016. Twenty-two soil variables were measured, including routine soil testing of pH, cation exchange capacity, and extractable phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg), as well as nonroutine testing of sand concentration, total and particulate organic carbon (C) and nitrogen (N), and soil-test biological activity. Large statistical variations in nearly all variables occurred within a location. Severely deficient and heavily excessive levels of soil-test P and K were observed on the same farm and sometimes on the same paddock. Soil-test biological activity and total soil N also varied spatially within locations. High nutrient concentrations and soil-test biological activity were congregated in zones of several pastures, which could be related to historical winter hay-feeding and permanent drinking water locations. At the Piedmont location with recent winter hay feeding, both organic and inorganic indicators generally corresponded to the same enrichment zones. At the Coastal Plain location with abandonment of some historical feeding locations, soil-test P remained high near feeding stations, but soil-test K and total soil N became more uniformly distributed due to leaching and/or decomposition dynamics over time. We suggest that both organic and inorganic soil testing indicators should be measured to make nutrient recommendations for better resource utilization. Livestock managers are encouraged to sample pastures in expected zones of nutrient differentiation so that nutrients can be used efficiently and environmental threats can be mitigated.}, number={6}, journal={JOURNAL OF SOIL AND WATER CONSERVATION}, author={Franzluebbers, A. J. and Poore, M. H. and Freeman, S. R. and Rogers, J. R.}, year={2019}, pages={571–583} }
 @article{costa crusciol_ferrari neto_mui_franzluebbers_costa_amaral castro_ribeiro_costa_2019, title={Rhizobial Inoculation and Molybdenum Fertilization in Peanut Crops Grown in a No Tillage System After 20 Years of Pasture}, volume={43}, ISSN={["0100-0683"]}, DOI={10.1590/18069657rbcs20170399}, abstractNote={Peanut (Arachis hypogea) is an important legume grain consumed by humans and utilized for effective nutrient cycling in a diverse cropping system. Areas that have been cultivated with perennial pasture for decades may have nutritional deficiencies and lack a sufficient population of atmospheric nitrogen-fixing bacteria. Molybdenum is an essential micronutrient that is part of the enzyme nitrogenase contained within symbiotic Bradyrhizobium bacteria, which are responsible for fixing nitrogen in legumes. Our objective was to evaluate the effects of application of Mo at different rates and a rhizobial inoculant on peanut growth characteristics. The experiment was conducted in the 2009/2010 growing season in a no-tillage cropping system following 20-year use as pasture [Urochloa brizantha (Syn. Brachiaria brizantha)]. The experimental design was a randomized complete block with four replicates. The main plots were characterized by peanut inoculation with Bradyrhizobium inoculant or without, and the split plots were characterized by different rates of molybdenum (0, 50, 100, and 200 g ha-1) applied to leaves in the form of ammonium molybdate. The nutritional status of plants, nodulation (number of nodules and nodule dry matter per plant), nitrogenase activity, and nitrogenase specific activity were evaluated at 45 and 64 days after emergence (DAE). The yield components and kernel yield were evaluated at the end of the growing season. Nitrogenase enzyme activity at 64 DAE approximately doubled, and the number of pods per plant was greater with inoculation than without, both of which led to greater yields of pods and kernels. In long-term pasture areas, inoculation and molybdenum fertilization greater than the currently recommended rate appear to be necessary to increase pod and kernel yield per hectare of peanut when managed under no-tillage.}, journal={REVISTA BRASILEIRA DE CIENCIA DO SOLO}, author={Costa Crusciol, Carlos Alexandre and Ferrari Neto, Jayme and Mui, Tsai Siu and Franzluebbers, Alan Joseph and Costa, Claudio Hideo and Amaral Castro, Gustavo Spadotti and Ribeiro, Livia Cristina and Costa, Nidia Raquel}, year={2019} }
 @article{franzluebbers_pershing_2018, title={Soil Test Biological Activity with the Flush of CO2: II. Greenhouse Growth Bioassay from Soils in Corn Production}, volume={82}, ISSN={["1435-0661"]}, DOI={10.2136/sssaj2018.01.0024}, abstractNote={
Core Ideas
Grass growth in the greenhouse was dependent on soil nitrogen mineralization.
Soil‐test biological activity was a valuable indicator of nitrogen mineralization.
Biological activity, residual inorganic nitrogen, and total nitrogen were most important.
Soil nitrogen (N) mineralization is variably affected by management and edaphic conditions. A routine soil test that reflects both soil biological activity and N mineralization could improve predictions for N fertilizer recommendations to cereal grains on different soil types and landscape settings. We collected soils from 47 corn production fields in North Carolina and Virginia at depths of 0 to 10, 10 to 20, and 20 to 30 cm and evaluated soil C and N characteristics in association with sorghum‐sudangrass [Sorghum bicolor (L.) Moench ssp. Drummondii] dry matter production and N uptake during 6 to 8 wk of growth in the greenhouse. Plant dry matter and N uptake were strongly associated, as expected. Plant available N (sum of net N mineralization during 24 d of aerobic incubation + residual inorganic N) had the strongest association with plant dry matter production (r2 = 0.76) and N uptake (r2 = 0.85). However, the flush of CO2 during a 0‐ to 3‐d period following rewetting of dried soil was nearly equally effective at r2 = 0.74 and r2 = 0.76, respectively. Multiple regression models with 4 ± 2 additional variables led to r2 = 0.88 ± 0.10 among different separations of data based on depth, region, and soil textural class. We suggest the optimum combination of variables to predict soil N availability would be the flush of CO2, residual inorganic N, and total soil N concentration, as they balance relevant scientific information with limited soil‐testing resources (time and labor). We demonstrated that the flush of CO2 was a rapid and reliable indicator of soil N availability.}, number={3}, journal={SOIL SCIENCE SOCIETY OF AMERICA JOURNAL}, author={Franzluebbers, Alan J. and Pershing, Mary R.}, year={2018}, pages={696–707} }
 @article{franzluebbers_pershing_crozier_osmond_schroeder-moreno_2018, title={Soil-Test Biological Activity with the Flush of CO2: I.C and N Characteristics of Soils in Corn Production}, volume={82}, ISSN={["1435-0661"]}, DOI={10.2136/sssaj2017.12.0433}, abstractNote={
Core Ideas
Soil nitrogen mineralization can be predicted with the flush of CO2.
Soil texture does not alter the relationship between the flush of CO2 and N mineralization.
Large quantity of mineralizable N in surface soils is possible with conservation management.
The flush of CO2 is an appropriate indicator for soil‐test biological activity.
The flush of CO2 is a rapid and reliable indicator of soil N availability.
Nitrogen limits crop production when insufficient and harms the environment when excessive. Tailoring N inputs to cropping systems remains a high priority to achieve production and environmental goals. We collected soils from 47 corn (Zea mays L.) production fields in North Carolina and Virginia at depths of 0 to 10, 10 to 20, and 20 to 30 cm and evaluated soil C and N characteristics in association with soil N mineralization. Soil organic C at a depth of 0 to 10 cm varied among sites from ∼10 to 80 g kg–1, and generally declined with depth because of many sites with no‐tillage management. Net N mineralization during 24 d of aerobic incubation (25°C, 50% water‐filled pore space) was 54 to 114 mg N kg–1 (24 d)–1 at 0 to 10 cm, 22 to 41 mg N kg–1 (24 d)–1 at 10 to 20 cm, and 12 to 22 mg N kg–1 (24 d)–1 at 20 to 30 cm (middle 50% of observations at each depth). Total soil N was positively associated with net N mineralization (r2 = 0.58), but the flush of CO2 during 3 d was even more closely associated with net N mineralization (r2 = 0.77). Association between the flush of CO2 and net N mineralization did not change significantly when data were sorted by different regions or soil textural classes. The flush of CO2 is a rapid, reliable, and robust indicator of soil‐test biological activity. The strong association of the flush of CO2 with net N mineralization also corroborated use of the flush of CO2 as a rapid and reliable indicator of soil N availability.}, number={3}, journal={SOIL SCIENCE SOCIETY OF AMERICA JOURNAL}, author={Franzluebbers, Alan J. and Pershing, Mary R. and Crozier, Carl and Osmond, Deanna and Schroeder-Moreno, Michelle}, year={2018}, pages={685–695} }
 @article{franzluebbers_pehim-limbu_poore_2018, title={Soil-Test Biological Activity with the Flush of CO2: IV. Fall-Stockpiled Tall Fescue Yield Response to Applied Nitrogen}, volume={110}, ISSN={["1435-0645"]}, DOI={10.2134/agronj2018.03.0146}, abstractNote={Core Ideas
Soil biological activity is a reliable indicator of soil nitrogen availability.
Nitrogen fertilization of fall stockpiled tall fescue should be adjusted based on soil testing.
The flush of CO2 is a robust indicator of soil biological activity.
A new paradigm of soil testing based on soil biological activity is possible.
Fall stockpiling of tall fescue (Lolium arundinaceum) in the southeastern United States is promoted as an ecologically favorable cattle management approach to avoid the financial and environmental burdens of winter hay feeding. We hypothesized that soil N mineralization should be an important factor controlling forage yield response to N fertilizer. We conducted 55 N fertilizer trials in combination with analyses of soil C and N fractions at multiple locations in Georgia, North Carolina, Virginia, and West Virginia during two seasons. Plant‐available N, as a combination of residual inorganic N + mineralizable N at depth of 0 to 10 cm, was significantly negatively related with extent of forage dry matter response to N fertilizer input. Large variations in economically optimum N fertilizer requirement (EONR) occurred among fields, but when several fields were averaged along a gradient of soil biological activity, a strong negative yield response with increasing soil‐test biological activity emerged. With moderate soil‐test biological activity of 200 mg CO2–C kg–1 soil 3 d–1, EONR was 20 kg N Mg–1 forage dry matter (a value similar to current N fertilizer recommendations). However, with progressively greater soil‐test biological activity up to 600 mg CO2–C kg–1 soil 3 d–1, EONR declined in a nonlinear manner to near zero. These results illustrate that N fertilizer recommendations for fall stockpiled tall fescue pastures should be a function of soil‐test biological activity as an indicator of biologically active N. Greater economic and environmental sustainability would likely be attainable with a shift to recognizing soil biological activity in an ecologically oriented fertilization paradigm.}, number={5}, journal={AGRONOMY JOURNAL}, author={Franzluebbers, Alan J. and Pehim-Limbu, Smriti and Poore, Matt H.}, year={2018}, pages={2033–2049} }
 @article{pariz_costa_crusciol_meirelles_castilhos_andreotti_costa_martello_souza_protes_et al._2017, title={Production, nutrient cycling and soil compaction to grazing of grass companion cropping with corn and soybean}, volume={108}, ISSN={["1573-0867"]}, DOI={10.1007/s10705-016-9821-y}, abstractNote={Agricultural management systems are needed to simultaneously enhance production, promote plant diversity, improve nutrient cycling and reduce soil compaction. We investigated the effects of intercropped forage grass on production of corn (Zea mays L.) harvested for silage at 0.20 and 0.45 m height in the summer, as well as on production of subsequent forage, soybean [Glycine max (L.) Merr.] harvested for silage, nutrient cycling and soil responses on a Typic Haplorthox in Botucatu, São Paulo State, Brazil. Palisade grass cv. BRS Piatã [Urochloa brizantha cv. BRS Piatã] was the introduced companion crop with corn (Years 1 and 2), while signal grass [Urochloa decumbens cv. Basilisk] was the residual weedy species in comparison. Guineagrass cv. Aruãna [Megathyrsus maximus cv. Aruãna] was the introduced companion crop with soybean (Year 3), with only a residual effect of crop systems from the previous two years. After the corn silage harvest, pasture was grazed by lambs in winter/spring using a semi-feedlot system. When cut at 0.45 m compared with 0.20 m height, corn intercropped with palisade grass had greater leaf nutrient concentration, improved agronomic characteristics, forage mass of pasture for grazing by lambs, greater surface mulch produced, and greater quantity of N, P and K returned to soil. Greater soil organic matter, P, K and Mg concentration, and base saturation in the surface soil depth and lower soil penetration resistance at all depths occurred at 0.45 m than at 0.20 m corn silage cutting height intercropped with palisade grass. Analyzing the system as a whole, harvesting corn silage crop with palisade grass intercrop at 0.45 m height was the most viable option in this integrated crop-livestock system.}, number={1}, journal={NUTRIENT CYCLING IN AGROECOSYSTEMS}, author={Pariz, Cristiano M. and Costa, Ciniro and Crusciol, Carlos A. C. and Meirelles, Paulo R. L. and Castilhos, Andre M. and Andreotti, Marcelo and Costa, Nidia R. and Martello, Jorge M. and Souza, Daniel M. and Protes, Verena M. and et al.}, year={2017}, month={May}, pages={35–54} }
 @article{deiss_franzluebbers_amoozegar_hesterberg_polizzotto_cubbage_2017, title={Soil Carbon Fractions from an Alluvial Soil Texture Gradient in North Carolina}, volume={81}, ISSN={0361-5995}, url={http://dx.doi.org/10.2136/sssaj2016.09.0304}, DOI={10.2136/sssaj2016.09.0304}, abstractNote={
Core Ideas
Total, mineral‐associated, and mineralizable C fractions varied along a soil texture gradient.
Specific surface area and Fe oxyhydroxides were positively associated with clay concentration.
Soil C fractions were positively associated with surface area and Fe oxides.
Aluminum oxide was not related to clay concentration or specific surface area.
Mineralizable C had the most complex relationship with clay concentration.
Soil texture is known to affect soil organic C (SOC) concentration and microbial activity, but these relationships are not always straightforward. We characterized total, mineral‐associated, and mineralizable C fractions along a gradient of soil texture within a flood plain field in the Coastal Plain region of North Carolina. Soil was collected from 0‐ to 5‐, 5‐ to 15‐, and 15‐ to 30‐cm depth intervals at 204 locations within a 7‐ha area. Samples were analyzed for soil particle size distribution, specific surface area (SSA), oxalate‐extractable Al and Fe to estimate short‐range‐ordered (i.e., poorly crystalline) oxyhydroxides, and soil C fractions. Overall, relationships among soil C fractions, textural classes, and depths were complex. Both SOC (0.4–13.9 g kg–1 soil) and mineral‐associated organic C (0–12 g kg–1 soil) increased as soil clay concentration increased (73–430 g kg–1 soil), but having two distinct slopes in each relationship with an inflection point of ∼150 g clay kg–1 soil at 0 to 5 and 5 to 15 cm and an inflection point of ∼250 g clay kg–1 soil at 15 to 30 cm. As clay concentration increased, SSA (12–76 m2 g–1 soil) and oxalate‐extractable Fe (0.45–5.9 g kg–1 soil) also increased. A weaker relationship was observed between oxalate‐extractable Al (0.38–1.5 g kg–1 soil) and either SSA or mineral‐associated organic C. Mineralizable C increased with increasing clay concentration up until 143 ± 3, 152 ± 5, and 161 ± 11 g kg–1 (0–5, 5–15, and 15–30 cm, respectively), but decreased (0–5 and 5–15 cm) or stayed constant (15–30 cm) at higher clay concentrations. On the basis of untested observations, we surmise that binding of C to oxalate‐extractable Fe contributed to the accumulation of SOC and suppression of mineralizable C as the clay concentration increased. These results suggest that complex soil texture–physicochemical interactions underlie the inherent fertility of floodplain soils.}, number={5}, journal={Soil Science Society of America Journal}, publisher={Wiley}, author={Deiss, Leonardo and Franzluebbers, Alan J. and Amoozegar, Aziz and Hesterberg, Dean and Polizzotto, Matthew and Cubbage, Frederick W.}, year={2017}, month={Sep}, pages={1096–1106} }
 @article{deiss_franzluebbers_moraes_2017, title={Soil Texture and Organic Carbon Fractions Predicted from Near-Infrared Spectroscopy and Geostatistics}, volume={81}, ISSN={["1435-0661"]}, DOI={10.2136/sssaj2016.10.0326}, abstractNote={
Core Ideas
Near‐infrared spectroscopy (NIRS) was appropriate for predicting soil texture and C.
Both linear and nonlinear multivariate models could be used for NIRS calibration.
Soil texture was predicted with greater precision than organic C fractions.
Near‐infrared spectroscopy and kriging were a useful combination for assessing spatial variation.
Near‐infrared spectroscopy (NIRS) and geostatistics are relatively unexplored tools that could reduce the time, labor, and costs of soil analysis. Our objective was to efficiently determine lateral and vertical distributions of soil texture and soil organic C (SOC) fractions in an agroforestry system (a 7‐ha field) on a Coastal Plain site in North Carolina. To predict selected properties from a large number of soil samples collected from this field, NIRS was calibrated against laboratory‐determined properties. Support vector machines was a multivariate model that performed better than partial least squares to obtain greater precision with NIRS for all soil properties. To predict soil properties with precision across the field, geostatistical modeling with maximum likelihood and ordinary kriging was used. When we combined the two modeling processes, the root mean square error (RMSE) and the RMSE relative to the dataset mean (%RMSE) were 67 g kg‐1 for sand (9.3% RMSE), 34 g kg‐1 for clay (22.7% RMSE), 1.63 g kg‐1 for total organic C (26.7% RMSE), 0.67 g kg‐1 for particulate organic C (36.1% RMSE), and 24 mg CO2–C kg‐1 3 d‐1 for the flush of CO2 (29% RMSE). We conclude that the combination of NIRS and kriging produced acceptable errors and therefore could be used to predict the spatial distribution of soil texture and SOC fractions in this agroforestry system to allow efficient assessment of management changes with time and better predict small‐scale input requirements.}, number={5}, journal={SOIL SCIENCE SOCIETY OF AMERICA JOURNAL}, author={Deiss, Leonardo and Franzluebbers, Alan J. and Moraes, Anibal}, year={2017}, pages={1222–1234} }
 @article{pariz_costa_crusciol_castilhos_meirelles_roca_pinheiro_kuwahara_martello_cavasano_et al._2017, title={Lamb production responses to grass grazing in a companion crop system with corn silage and oversowing of yellow oat in a tropical region}, volume={151}, ISSN={["1873-2267"]}, DOI={10.1016/j.agsy.2016.11.004}, abstractNote={Integrated crop-livestock systems in regions with dry winters could be a viable option to increase food production during periods of irregular rain and reduced pasture availability. A corn (Zea mays L.) silage production system with cover crops of (a) the weedy growth of signal grass [Urochloa decumbens (Stapf) R. Webster "Basilisk"] and (b) palisade grass [Urochloa brizantha (Hochst. ex A. Rich.) R. Webster 'Marandu' and 'Piatã'], both with a 0.20- and 0.45-m silage cutting height, was employed in the summer and autumn. Yellow oat (Avena byzantina cv. São Carlos) was oversown in these systems in the winter and spring. The pasture production, the daily ration intake, the performance and carcass characteristics of lambs (Ovis aries) grazing these pastures in a semi-feedlot system (supplemented with silage and concentrate), and the revenue were investigated. The experiment was repeated in the same location for two growing seasons (2010–2011 and 2011–2012) on a Typic Haplorthox in Botucatu, São Paulo, Brazil. Analyzing the system as a whole, intercropping corn silage with palisade grass cv. Marandu (followed by palisade grass cv. Piatã) with a cutting height of 0.45 m combined with yellow oat oversowing was the most robust option for enhancing productivity. The pasture formation for lamb finishing in a semi-feedlot system, the reduction of silage and concentrate intake, and greater live weight and carcass gains per hectare were key attributes for improving the economic viability of this integrated crop-livestock system. Thus, these crop systems were a viable option for the diversification of agricultural activities in tropical regions.}, journal={AGRICULTURAL SYSTEMS}, author={Pariz, Cristiano M. and Costa, Ciniro and Crusciol, Carlos A. C. and Castilhos, Andre M. and Meirelles, Paulo R. L. and Roca, Roberto O. and Pinheiro, Rafael S. B. and Kuwahara, Frank A. and Martello, Jorge M. and Cavasano, Francielli A. and et al.}, year={2017}, month={Feb}, pages={1–11} }
 @article{pariz_costa_crusciol_meirelles_castilhos_andreotti_costa_martello_souza_sarto_et al._2016, title={Production and soil responses to intercropping of forage grasses with corn and soybean silage}, volume={108}, DOI={10.2134/agronj2016.02.0082}, abstractNote={Agricultural management systems are needed to simultaneously enhance production, and improve soil quality. We investigated the effects of intercropped grass on production of corn (Zea mays L.) harvested for silage at 0.20 and 0.45 m height in the summer, as well as on production of subsequent forage, silage soybean [Glycine max (L.) Merr.], and soil responses on a Typic Haplorthox in Botucatu, SP, Brazil. Palisade grass [Urochloa brizantha (Hochst. ex A. Rich.) R. Webster ‘Marandu’] was the introduced companion crop with corn (Years 1 and 2), while signal grass [Urochloa decumbens (Stapf) R. Webster ‘Basilisk’] was the residual weedy species in comparison. Guinea grass [Urochloa maxima (Jacq.) R. Webster ‘Aruãna’] was the introduced companion crop with soybean (Year 3), with only a residual effect of crop systems from the previous 2 yr. When cut at 0.45 m compared with 0.20 m height, corn intercropped with palisade grass had greater leaf nutrient concentrations, agronomic characteristics, forage mass of pasture for grazing by lambs (Ovis aries), greater surface mulch produced, and greater quantity of N, P, and K returned to soil. Greater soil organic matter, P, K, and Mg concentration, and base saturation in the surface soil depth and lower soil penetration resistance at all depths occurred at 0.45 m than at 0.20 m corn silage cutting height intercropped with palisade grass. Analyzing the system as a whole, harvesting corn silage crop with palisade grass intercrop at 0.45 m height was the most viable option in this integrated crop–livestock system (ICLS).Core Ideas

Agricultural management systems are needed to enhance production and improve soil quality.
After corn silage harvest, pasture was grazed by lambs in winter/spring using a semi‐feedlot system.
Harvesting corn silage crop with palisade grass intercrop at 0.45 m height was the most viable option.
}, number={6}, journal={Agronomy Journal}, author={Pariz, C. M. and Costa, C. and Crusciol, C. A. C. and Meirelles, P. R. L. and Castilhos, A. M. and Andreotti, M. and Costa, N. R. and Martello, J. M. and Souza, D. M. and Sarto, J. R. W. and et al.}, year={2016}, pages={2541–2553} }
 @article{mateus_crusciol_pariz_borghi_costa_martello_franzluebbers_castilhos_2016, title={Sidedress Nitrogen Application Rates to Sorghum lntercropped with Tropical Perennial Grasses}, volume={108}, ISSN={["1435-0645"]}, DOI={10.2134/agronj2015.0236}, abstractNote={Intercropping sorghum [Sorghum bicolor (L.) Moench] with tropical perennial grasses and using the appropriate rate of sidedress N application can maximize grain yield (GY) and revenue and can improve land‐use efficiency (LUE). The effects of monocropped sorghum (MS) or sorghum intercropped with palisadegrass (Urochloa brizantha cv. Marandu; SPG) or guineagrass (Panicum maximum cv. Mombaça; SGG) and sidedress N application rates of 0, 50, 100, and 200 kg ha−1 on leaf nutrient concentration, sorghum GY, revenue, and LUE were investigated during three growing seasons at Botucatu, SP, Brazil, on a clay, kaolinitic, thermic Typic Haplorthox. The SGG treatment had lower leaf N, P, and K concentrations and lower 1000‐grain weight, shoot dry matter, and GY than MS and SPG at all sidedress N rates; MS and SPG at 200 kg ha−1 of sidedress N resulted in greater sorghum GYs (3.80 and 3.81 Mg ha−1, respectively). The forage dry matter production (FDMP) and crude protein of tropical perennial grasses were higher as a function of the sidedress N rate. The SGG treatment resulted in negative net profits for all sidedress N rates. The MS and SPG treatments (independent of sidedress N rates) resulted in similar net profits (approximately US$85 and $60 ha−1, respectively). The SPG treatment using 200 kg ha−1 of sidedress N resulted in a higher land equivalent ratio and relative N yield (1.27 and 123%, respectively) than SGG (0.96 and 107%, respectively). The SPG treatment with 200 kg ha−1 of sidedress N is the best option for increasing sorghum GY, revenue, and FDMP from autumn to part of the spring and for improving LUE.}, number={1}, journal={AGRONOMY JOURNAL}, author={Mateus, G. P. and Crusciol, C. A. C. and Pariz, C. M. and Borghi, E. and Costa, C. and Martello, J. M. and Franzluebbers, A. J. and Castilhos, A. M.}, year={2016}, pages={433–447} }
 @article{franzluebbers_2013, title={Pursuing robust agroecosystem functioning through effective soil organic carbon management}, volume={4}, ISSN={["1758-3012"]}, DOI={10.4155/cmt.12.78}, abstractNote={Soil organic matter is a key indicator of many ecosystem functions, particularly in agricultural systems. With carbon as its majority constituent (∼58%), soil organic matter is a key variable relating production and environmental responses. However, it is argued that depth distribution of soil organic carbon (SOC) may be more important in understanding how agriculture affects ecosystem services derived from soil than the total quantity of SOC. Conservation agricultural systems lead to highly stratified SOC, which helps to protect soil from erosion and prevent runoff loss of nutrients (i.e., water quality improvement), creates a concentrated organic habitat for nutrient storage and soil biological diversity (i.e., soil quality improvement) and promotes a structurally stable pore network connecting surface and subsurface to avoid negative impacts on soil aeration and GHG emissions (i.e., air quality improvement). A protocol is described to calculate the stratification ratio of soil organic matter fractions from a diversity of sampling procedures, which may be relevant in different ecoregions and conditions of the soil.}, number={1}, journal={CARBON MANAGEMENT}, author={Franzluebbers, Alan J.}, year={2013}, month={Feb}, pages={43–56} }
 @article{tian_franzluebbers_granato_cox_c. o'connor_2013, title={Stability of soil organic matter under long-term biosolids application}, volume={64}, ISSN={["1873-0272"]}, DOI={10.1016/j.apsoil.2012.12.001}, abstractNote={Little is know on the impact of biosolids application on soil organic matter (SOM) stability, which contributes to soil C sequestration. Soil samples were collected in 2006 at plow layer from fields that received liquid and dry municipal biosolids application from 1972 to 2004 at the cumulative rate of 1416 Mg ha−1 in mined soil and 1072 Mg ha−1 in nonmined soil and control fields that received chemical fertilizer at Fulton County, western Illinois. The biosolids application increased the soil microbial biomass C (SMBC) by 5-fold in mined soil and 4-fold in nonmined soil. The biosolids-amended soils showed a high amount of basal respiration and N mineralization, but low metabolic quotient, and low rate of organic C and organic N mineralization. There was a remarkable increase in mineral-associated organic C from 6.9 g kg−1 (fertilizer control) to 26.6 g kg−1 (biosolids-amended) in mined soil and from 8.9 g kg−1 (fertilizer control) to 23.1 g kg−1 (biosolids-amended) in nonmined soil. The amorphous Fe and Al, which can improve SOM stability, were increased by 2–7 folds by the long-term biosolids application. It is evident from this study that the biosolids-modified SOM resists to decomposition more than that in the fertilizer treatment, thus long-term biosolids application could increase SOM stability.}, journal={APPLIED SOIL ECOLOGY}, author={Tian, G. and Franzluebbers, A. J. and Granato, T. C. and Cox, A. E. and C. O'Connor}, year={2013}, month={Feb}, pages={223–227} }