Research Project: Strategies to Support Resilient Agricultural Systems of the Southeastern U.S.

Location: Plant Science Research

2023 Annual Report

Objectives
Objective 1. Assess conservation agricultural systems for the capacity to enhance productivity, reduce environmental impacts, build strong rural connections, and be profitable. Objective 2. Develop soil biological testing to improve nitrogen fertilizer recommendations for grain and forage crops. Objective 3. Identify crop stress-tolerance traits, assess germplasm and identify genetic sources of these traits for cultivar improvement. Sub-objective 3A. Identify sources of heat stress tolerance in soybean and wheat. Sub-objective 3B. Identify sources of ozone tolerance in soybean and wheat. Sub-objective 3C. Characterize root architecture under heat or ozone stress. Sub-objective 3D. Characterize the impact of heat, ozone stress, and management on the microbial communities associated with plant roots.

Approach
Two long-term field experiments located at the Farming Systems Research Unit at Goldsboro, North Carolina, are the basis for the research on conservation agricultural system evaluation. One experiment compares conventional cropping, organic agriculture, integrated crop-livestock system, plantation forestry, and a naturalized fallow. Soil samples from all treatments will be tested periodically for soil organic carbon and nitrogen fractions, bulk density, water infiltration, and penetration resistance. Crop, animal, and timber production data will be used to assess the trajectory of sustainability from different farming systems. Intact root systems will be characterized for long-term management effects on microbial communities associated with roots using DNA technology (see below). The second long-term field experiment is an agroforestry study with the presence or absence of trees with the alleys planted to native warm-season grasses and tested for effects of harvest management. Forage, animal, and timber production data along with soil resource data will be used to assess the sustainability of the different types of forage utilization and type of shade management for cattle. Soil biological testing to improve nitrogen fertilizer recommendations will be conducted on research stations and on-farm trials. Treatments will be a series of different nitrogen rates to determine yield response of a crop to supplemental nitrogen. Soil biological activity will be determined with the flush of CO2 following rewetting of dried soil method and results used to develop site-specific fertilizer recommendations. Soybean and wheat germplasm selected in consultation with plant breeders will be screened for response to heat stress and elevated ozone. Plant response to heat stress will be assessed based on yield and harvest index using temperature gradient greenhouses and Air Exclusion System (AES) field technology to impose elevated temperature treatments. Plant response to ozone stress will be assessed based on foliar injury and yield using greenhouse chambers and open-top field chambers (OTC) to provide elevated ozone treatments. Genotype differences in biochemical (antioxidant enzymes and metabolites) and physiological (chlorophyll fluorescence, photosynthesis, respiration, and stomatal conductance) processes will be characterized to identify useful traits for phenotyping during development of cultivars with improved stress tolerance. Plants evaluated for heat stress and ozone tolerance will also be assessed for differences in root morphology and root-associated microbes. Root systems will be divided into root classes and assessed for genotype and treatment effects on biomass, diameter and length using high resolution scanners and WinRhizo software. Root associated microbes will be separated from roots and the rhizosphere DNA isolated. Bacterial/archaeal and fungal primer pairs will be used to amplify rhizosphere bacterial 16S rRNA genes and fungal Internal Transcribed Spacer regions (ITS1, ITS2). After sequencing, 16S rRNA sequences and ITSs will be analyzed to characterize genotype and stress effects on root associated microbial communities.

Progress Report
Research reports addressed soil health, soil carbon sequestration, nutrient cycling, pasture management, and sustainable agricultural production. Soil-test biological activity was developed as an indicator of nitrogen availability so that producers can fine-tune nitrogen applications for greater production and profit, as well as to limit nitrogen losses to the environment. Soil-test biological activity was verified as a robust indicator of soil organic nitrogen supply across a diversity of land uses and physiographic regions across the eastern United States (US). Innovative cropping systems that used rotation of pastures and crops over time and organically managed cropping systems stored more organic matter and allowed greater nutrient availability than other more conventional systems. Multi-species cover cropping improved soil biological condition soon after adoption. Root-zone enrichment calculations illustrated great potential for significant soil organic carbon sequestration, as well as total soil nitrogen and soil-test biological activity, when conservation tillage practices were deployed continuously throughout the crop rotation. Spatial variation of nutrients affected by winter pasture feed management were reduced with adoption of improved grazing management. Greenhouse gas emissions from grazing lands in the eastern US were reviewed. Soil health conditions improved with age of pastures and fall-stockpiling of tall fescue in the eastern US. Many mature pastures had sufficient nitrogen cycling through mineralization of organic matter that exogenous nitrogen and phosphorus fertilization may not always be profitable. Soil organic carbon sequestration was estimated from calculations of root-zone enrichment. Reanalyzed literature data suggest that soil organic carbon sequestration may not be different across different regions, but the inherent level of soil organic carbon at 12-inch depth may be different due to pedogenic conditions. Surface residue mass can be adjusted for soil contamination with knowledge of carbon concentration. Significant collaborations occurred with investigators at (1) the ARS lab in El Reno, OK to study soil organic matter fractions as affected by cattle stocking method; (2) Institut National de la Recherche Agronomique (INRA) in France to review crop-pasture rotations; (3) São Paulo State University in Brazil to study peanut inoculation and application of molybdenum, nitrogen fertilization of grass cover crops, impacts of lime and gypsum application on soil organic matter, corn grain and silage production with intercropping of tropical forage grasses, combinations of fall and spring cover cropping on soil health; (4) Federal University of Parana and Federal University of Rio Grande do Sul in Brazil to determine changes in soil chemical properties from grazing of cover crops; (5) Federal Technical University of Parana in Brazil to test how much soil-test biological activity changes in response to sampling during a growing crop and how nitrogen fertilizer and rotation of grazed cover crops affect nitrogen, phosphorus, and potassium nutrition of corn; (6) North Carolina State University to evaluate geospatial distribution of organic and inorganic nutrients in surface soil on private farms; (7) Cornell University and Agriculture Food and Agri-Food Canada to share perspectives on how livestock manures can be integrated with regional land uses; and (8) Kansas State University and other investigators from Corteva Agriscience, Agriculture and Agri-Food Canada, Iowa State University, University of Minnesota, North Dakota State University, University of Illinois, Michigan State University, and Brigham Young University to assess published corn yield data from 1104 field studies conducted between 1999 and 2019; and (9) Clemson University to review literature and assemble on-farm data to assess soil health conditions. Research addressed adaptation of crops to climate change through studies of plant response to ozone air pollution and elevated temperature. Custom-built exposure systems capable of simulating future climate scenarios were used to screen germplasm and assess plant response to rising temperature and ozone air pollution. Field trials using our Air Exclusion System demonstrated that season-long elevated temperatures of +3-4 degrees centigrade reduced soybean yield by 25% for cultivar ‘Jake”, and the results were used by collaborators to improve crop growth models. During this project, our team developed a Temperature Gradient Greenhouse based on the published design of Tom Sinclair (Sinclair et al. 1995. Biotronics 24, 99-108). This Temperature Gradient Greenhouse system was utilized to screen for heat stress response to season-long, 24-hour per day, elevated temperature treatments of +2 and +4 degrees Celsius relative to an unheated air control. Collaborative research with plant breeders identified significant genetic variation in yield response to elevated temperature for barley, soybean, and wheat. For sixteen soybean genotypes tested, yield responses ranged from a 50% yield stimulation to a yield loss of 30% in the +2 Celsius treatment and ranged from a 10% yield stimulation to a yield loss of 40% in the +4 Celsius treatment. The screening of soybean for heat stress response was supported by grants from the Untied Soybean Board. Small grains were more sensitive to rising temperature than soybeans. For two barley genotypes tested, yield losses of 20 to 60% were observed in the +2 Celsius treatment with higher losses of 35 to 80% in the +4 Celsius treatment. For nine wheat genotypes tested, yield losses of 15 to 40% were observed in both the +2 and +4 Celsius treatments. Root analyses demonstrated that the heat resistance in wheat was associated with increased fine roots and high ratios of shoots to roots. These heat-tolerant root traits will help breeders develop warming-resistant wheat. In collaboration with plant breeders, soybean and wheat germplasm were screened for response to ozone air pollution using greenhouse exposure chambers and open-top field chambers. Significant genetic variation in ozone response was found for both crop species. Ozone exclusion was identified as a leaf trait in ozone tolerant ‘Fiskeby III’ soybean plant introduction. The trait reduces ozone damage by limiting ozone uptake into leaves through lower stomatal conductance while maintaining high rates of photosynthesis. The ozone exclusion trait was associated with increases water use efficiency, suggesting a linkage between ozone tolerance and drought stress tolerance. Breeding lines developed from hybridization of Fiskeby III or Fiskeby V (both ozone and drought tolerant with low yield potential) with the elite southern cultivar Holladay (stress sensitive with high yield potential) were screened for ozone tolerance in open-top chambers and for drought tolerance in field plots. Several lines with high yield potential have been tentatively identified as drought tolerant, and two of these lines exhibited significant ozone tolerance. These lines are undergoing further testing for possible germplasm release. Results from root trait analyses showed that elevated ozone reduces root growth by impacting carbon and nitrogen metabolism. Root proteome analysis from two soybean genotypes with contracting ozone sensitivity showed that the effect of ozone in roots is complex and distinct between flowering and pod-filling stages. Changes in the abundance of proteins correspond to carbon and nitrogen metabolism, secondary metabolites, antioxidant, and stress response pathways, differed between genotypes. Some of these changes may be in response to elevated ozone as an attempt to mitigate the effects of a challenging environment, and others are likely due to genetic differences that confer an adaptative advantage to the ozone resilient genotype. Long-term elevated ozone also presents strong negative impacts on soil microbial diversity and community, as well as soil carbon and nitrogen composition, which significantly affects agricultural ecosystems. Elevated ozone significantly decreased fungal diversity and complexity of microbial networks at different plant developmental stages, whereas bacterial diversity was more tolerant to ozone. Bacterial taxa were identified that may contribute to nitrogen (Chloroflexales) and carbon (Caldilineales and Thermomicrobiales) acquisition to support ozone resilience. Across multiple studies, elevated temperature, elevated ozone, and the combination of these treatments all reduce soybean root biomass, reduce root interactions with beneficial fungi, and favor the formation of fine roots, resulting in stimulation of organic carbon decomposition. Thus, rising temperature and elevated ozone pollution may reduce the capacity of soils to sequester carbon.

Accomplishments
1. Ozone air pollution exacerbates wheat rust disease. Our knowledge of the impacts of air pollution (ozone) and climate change on plant diseases is limited and at times conflicting due to the wide range of possible pathogen-environment interactions. A further challenge is the need for collaboration between diverse scientific disciplines. In this study, an international team of plant pathologists and plant physiologists from Egypt, North Carolina State University, and USDA-ARS at Raleigh, North Carolina grew wheat plants under combinations of elevated ozone and elevated carbon dioxide and then infected the plants with a stem rust pathogen. Ozone concentrations that mimic present day air pollution levels increased stem rust disease severity relative to low ozone conditions. In contrast, elevated carbon dioxide concentrations predicted for later in the 21st century did not significantly impact disease. The results suggest that air pollution may impact wheat production by exacerbating stem rust disease in regions where ozone pollution and the pathogen coexist. This supports the need to continue the development of wheat varieties with greater disease resistance.

2. Making better nitrogen fertilizer recommendations based on soil health condition. Nitrogen fertilizer is one of the most common field production inputs in agriculture. It is both necessary for achieving high productivity and threatens ecosystem integrity due to its easy transport to water bodies and emission to the atmosphere. A USDA scientist at Raleigh, North Carolina, led a series of investigations with a team of collaborators to understand how inherent soil nitrogen supply might supplement the need for nitrogen fertilizer inputs in corn and forage management systems. This synthesis article describes the premise, a review of current recommendations, an overview of soil health and biological activity, and a new approach for adjusting nitrogen fertilizer recommendations. This information will have immediate relevance to farmers, agribusiness dealers, agricultural service providers, and scientists.

3. Root-zone enrichment of soil organic matter improves with conservation management. Soil organic matter is an important attribute that contributes to soil fertility on the farm, as well as a potential sink for atmospheric carbon dioxide via soil carbon sequestration. The historic loss of soil organic matter from exploitive tillage management now offers the southeastern United States an opportunity to sequester carbon with conservation management systems. An ARS scientist at Raleigh, North Carolina, collected soil from different land uses on 25 research stations across North Carolina to determine the potential of surface soil to store carbon from conservation management with either no-till cropping, grassland management, or timber production. The results suggested that indeed conservation management was a beneficial strategy to improve soil organic carbon and total soil nitrogen of surface soils throughout North Carolina. Soil texture was an important co-factor but did not negate the positive impact of conservation management anywhere in the state. Woodland and grassland management were more effective at storing carbon and nitrogen than no-till cropland. These results will be important for agricultural advisors, farmers, extension specialists, and scientists in the region to promote more efficient, carbon-storing practices for agriculture to simultaneously meet the production and environmental demands needed to achieve a sustainable future.

4. The dynamics of microbial networks responding to nutrient allocation associated with adaptation in soybean to ground-level ozone. Ground-level ozone contributes to global warming, which is the most harmful greenhouse gas impacting agricultural ecosystems and food security. Soybean is a major United States (US) export crop, with a total export value at $34 billion in 2022, yet it is especially susceptible to ozone. As ozone pollution and warming substantially worsen, US soybean yield is projected to decline 28% by the year 2050. To optimize crop yield for a growing global population and maintain healthy agricultural ecosystems, Climate-Change/Air Quality Research at the Plant Science Research Unit, Raleigh, North Carolina, identified a soybean cultivar that is tolerant to elevated ozone pollution and used genomic sequencing technology to identify soil microorganisms that may assist this cultivar in adapting to elevated ozone pollution. The study identified symbiotic bacteria and fungi associated with soybean nutrient allocation. The findings demonstrated that while ozone does not penetrate soil, ozone can affect soil microbial communities through plant-mediated processes in the root zone. Symbiotic bacteria supporting plant ozone adaptation are potentially biofertilizers to enhance crop performance and improve agricultural ecosystems under environmental stress.

5. Impact of tropospheric ozone on root proteomes of two soybean genotypes with contrasting sensitivity to ozone. Ozone pollution is a serious environmental threat to the United States (US) economy and its food security. The US had soybean export revenue worth US$34 billion in 2022. However, there is evidence that the US is sustaining the greatest ozone impact on soybean yield loss when compared to other soybean exporters, a projected 28% yield loss by 2050. To confront this environmental challenge and optimize crop yield, USDA-ARS soybean breeders and scientists at the Plant Science Research Unit, Raleigh, North Carolina, compared two soybean genotypes that show similar characteristics and yield in the absence of ozone stress, but express contrasting phenotypes under elevated ozone conditions. The results demonstrate that elevated ozone rapidly decreases root growth and nodulation, which profoundly impairs nutrient acquisition and ultimately decreases seed productivity. By comparing root proteomic profiles of the contrasting genotypes, ozone was shown to alter metabolic pathways, including carbon metabolism, amino acid biosynthesis, and detoxification capability, which can impair root development and function. This finding provides insight into root traits that can be used to develop stress tolerant, high-yielding soybean cultivars.

6. Concept of root-zone enrichment calculation on farms summarized. Soil organic matter accumulation contributes to improved soil health condition, particularly after a history of degradative land use. Soil-test biological activity characterizes soil microbial activity and is an active fraction of organic matter that is responsive to conservation management. This essay was prepared by a USDA scientist at Raleigh, North Carolina, to summarize the need, concept, and method of calculating root-zone enrichment of soil-test biological activity on private farms. Calculation of root-zone enrichment separates the influence of historical soil formation processes on organic matter fractions from that of contemporary management. This separation is particularly important when attempting to determine soil-test biological activity or soil organic carbon change in response to management across variable landscapes. It is suggested that reasonable farm-level estimates of soil-test biological activity and contents of soil organic carbon and nitrogen can be obtained with one to two dozen sampling sites on farms with a few differences in land use, a process that could help propel in-depth assessments of soil health condition and carbon sequestration.

7. Soil-test biological activity relates well to soil aggregation. Soil erosion continues to be a serious threat to the sustainability of agriculture. Conservation management is needed to protect the valuable soil resources around the country. An ARS scientist at Raleigh, North Carolina, conducted an evaluation of soil aggregation characteristics among soils managed with conventional-till cropland, no-till cropland, grassland, and woodland across 25 research stations in North Carolina. Resistance to water erosion was enhanced with no-till compared with conventional-till cropland. Perennial grasslands and woodlands that had no recent disturbance were more strongly aggregated than any of the croplands. Soil biological activity measurements were strongly associated with soil aggregation characteristics, reflecting the role that soil microorganisms play in gluing soil particles together, even in relatively sandy soil conditions. Results from this study can be used by farmers, extension advisors, and policy makers to make better decisions to protect soil with relatively simple, specific management changes or possibly through broader systems-level changes.

8. Forage and grazing land educational series on soil health released. Soil provides ecosystem services that benefit society. An ARS scientist at Raleigh, North Carolina, described to a farm stakeholder audience the benefits of soil health to farmers and society. Productivity, nutrient cycling, water cycling, and biodiversity are key services that can be provided by healthy soils under forage and grasslands. Results of this effort will inform farmers and extension personnel to aid in developing more resilient agricultural systems.

9. Sustainability of farming with forages described. Industrialization of agriculture in the last 70 years has resulted in simplification of biotic resources on farms, resulting in serious issues with resilience to pests, market vagaries, and climate change. More complex agricultural systems with integrated crop and livestock operations intertwined on farms or among farms could provide important benefits to build agricultural resilience. An ARS scientist at Raleigh, North Carolina, collaborated with a scientist from Institut National de Recherche pour l'agriculture, l'alimentation et l'nvironnement (INRAE) in Castanet-Tolosan, France to summarize recent research on diversifying agricultural systems with perennial and annual forages. This effort was needed to help create more diverse and functional agricultural systems to meet production and environmental goals. This manuscript is the full version of a presentation originally presented at the European Federation of Grasslands Congress in Caen, France. Results of this effort will benefit farmers, extension specialists, scientists, and policy makers to create more resilient agricultural systems.

10. Soil aggregation methodology compared. Soil aggregation is an important characteristic of agricultural soils. However, methodology for determining soil aggregation is variable, so comparison of approaches is needed. An ARS scientist at Raleigh, North Carolina, collaborated with investigators from São Paulo State University to compare results of dry-stable and water-stable aggregate determination from two fine-textured soils under differential long-term crop management as affected by initial soil sieving, i.e., passing a screen with 8-mm openings or with 4.75-mm openings. Sieving soil through 4.75 mm had only minor differences in relative aggregation characteristics compared with a more traditional approach of sieving soil initially through 8 mm prior to water-stable aggregation determination. However, relative variation was lower when sieved to pass 4.75 mm than when passing 8 mm, giving this procedure a potential advantage in identifying small changes with management. Large soil depth effects on dry-stable and water-stable aggregation were equally discerned with both sieving approaches. Soil sieved to pass 4.75 mm also allows a bulk sample to be used for multiple analytical tests in the laboratory, including importantly for soil-test biological activity and other C and N mineralization assays. These results will be useful to scientists and soil-testing laboratories to evaluate conservation management impacts on soil biophysical properties.

11. Stakeholder process to management of an invasive weed fails. Tropical spiderwort is a noxious, invasive weed that was detected in a long-term field experiment in the Coastal Plain region of North Carolina. A multi-stakeholder governance model was used to manage its invasion once it was detected at high levels. An ARS scientist at Raleigh, North Carolina, collaborated with investigators at North Carolina State University and field managers at North Carolina Department of Agriculture and Consumer Services to document this process. Removal of the pest was from a combination of monitoring, mapping, and physical removal. Over time, spiderwort population decreased logarithmically from more than 50,000 plants on 200 acres in 2005 to 19 plants in one acre in 2019, with a projection of full eradication by 2024. Unfortunately, regulators decided that fumigation of a few target fields was needed to lift the quarantine of the experimental area. This drastic ending step was disappointing to the different stakeholders who participated in the original plan. Important shortcomings that led to disappointment were that the original plan did not include specific milestones, and there was no definition of acceptable progress. Also, no financial limits were established, which concerned administrators about long-term financial issues. Multi-stakeholder governance can effectively address plant invasions, but the model should balance decision-making control.

12. Paired land-use assessment shows significant root-zone enrichment of soil carbon. Soil organic matter is a keystone indicator of sustainable soil management. An ARS scientist at Raleigh, North Carolina, collected soil from paired land uses of conventional-till cropland with (1) no-till cropland and (2) conservation grassland on multiple research stations in North Carolina to determine the potential of surface soil to store carbon. Across locations, surface residue and soil organic carbon and nitrogen were greater under no-till than conventional-till cropland. Conservation grassland also improved soil organic carbon and nitrogen compared with conventional-till cropland. A key distinction in this assessment was from separating the recent change in soil carbon and nitrogen from that of historical soil development processes. These results will be important for agricultural advisors, farmers, extension specialists, and scientists in the region to promote more efficient, carbon-storing practices for agriculture to simultaneously meet the production and environmental demands needed to achieve a sustainable future.

13. Perennial pasture renovation with annual forages does not improve soil health condition. Renovation of perennial pastures may be periodically needed to reestablish more desirable forage species or to improve nutrient and/or physical conditions of soil. A specific reason for renovation in the southeastern United States is to eliminate the wild toxic tall fescue variety and replace it with a friendly novel-endophyte tall fescue variety. This often requires some time to reduce the natural seed bank of wild tall fescue. A proposed method during seedbank elimination time is to use high-quality annual forages to overcome the expected decline in forage availability when killing an otherwise reliable forage source. An ARS scientist at Raleigh, North Carolina, partnered with the Amazing Grazing program at North Carolina State University and private farmers in different regions of the state to evaluate the soil health implications of a renovation strategy with simple and complex mixtures of annual forages. Neither annual forage treatment planted with no-till technologies caused significant improvement in soil health, but importantly also did not cause a decline in soil health condition. An additional finding from the study was the recognition of strong spatial variations at the local level that were sometimes more important than often recognized variations among physiographic regions, i.e., among coastal, piedmont, and mountain regions. The results of this research can be used by farmers, agricultural advisors, extension specialists, and scientists to make better decisions for pasture management to support productivity and environmental quality goals.

14. Greenhouse gas emissions and soil carbon storage in forage and grazing lands summarized. Management of forages and pasture-based livestock production systems can be a sink for carbon dioxide from the atmosphere via soil organic matter storage, but these systems can also be a source of greenhouse gas emissions via enteric methane and soil nitrous oxide following fertilization. A scientist from USDA Agricultural Research Service at Raleigh, North Carolina, collaborated with scientists from the National Institute of Agricultural Research in France on a summary of recent research and literature review in a book chapter describing the impacts of grassland management on soil carbon storage and greenhouse gas emissions. Ruminant livestock naturally emit enteric methane, but dietary quality and herd management can alter the emission index. Nitrous oxide is a powerful greenhouse gas that often increases following nitrogen fertilization, so accurate fertilizer recommendations can mute this emission source. These emissions can be offset by storage of carbon in soil organic matter during pasture development since grass roots and residues are important contributors to organic matter stabilization. This review will be useful for scientific investigators, policy makers, and non-governmental organizations interested in land management systems for mitigating and adapting to climate change.

Review Publications
Zentella Gomez, R., Burkey, K.O., Tisdale, R.H. 2023. Impact of tropospheric ozone on root proteomes of two soybean genotypes with contrasting sensitivity to ozone. Environmental and Experimental Botany. 208:105269. https://doi.org/10.1016/j.envexpbot.2023.105269.
Kumar, S., Wang, Y., Zhou, Y., Dillard, L., Li, F., Sciandra, C., Sui, N., Zentella Gomez, R., Borgnia, M., Alberto Bartesaghi, A., Sun, T., Zhou, P. 2023. Structure and dynamics of the Arabidopsis O-fucosyltransferase SPINDLY. Nature Communications. 14:1538. https://doi.org/10.1038/s41467-023-37279-1.
Zentella Gomez, R., Wang, Y., Zahn, E., Hu, J., Jiang, L., Shabanowitz, J., Hunt, D., Sun, T. 2023. SPINDLY o-fucosylates nuclear and cytoplasmic proteins involved in diverse cellular processes in plants. Plant Physiology. 191(3):1546-1560. https://doi.org/10.1093/plphys/kiad011.
El-Ghannam, M.K., Wassar, F., Morsy, S., Hafez, M., Parihar, C.M., Burkey, K.O., Abdallah, A.M. 2023. Controlled drainage in the Nile delta of Egypt: A promising approach for decreasing drainage off-site effects and enhancing yield and water use efficiency of wheat. Journal of Arid Land. 15:460-476. https://doi.org/10.1007/s40333-023-0095-3.
Hung, C., Wharton, K., Kittur, F., Chen, J., Umstead, M., Burwell, D., Thomas, M., Qi, Q., Zhang, J., Oldham, C., Burkey, K.O., Xie, J. 2023. A rapid alkalinization factor-like peptide EaF82 impairs tapetum degeneration during pollen development through induced ATP deficiency. Cells. 12(11):1542. https://doi.org/10.3390/cells12111542.
Leon, R.G., Creamer, N., Reberg-Horton, C., Franzluebbers, A.J. 2022. Eradication of Commelina benghalensis in a long-term experiment using a multistakeholder governance model: A case of regulatory concerns defeating ecological management success. Invasive Plant Science and Management. 15:152-159. https://doi.org/10.1017/inp.2022.23.
Franzluebbers, A.J., Tanaka, K.S., Momesso, L., Calonego, J.C., Crusciol, C. 2023. Mean-weight diameter of aggregation as affected by initial screen size of two fine-textured soils. Soil Science Society of America Journal. 87:644-655. https://doi.org/10.1002/saj2.20517.
Chabbi, A., Rumpel, C., Klumpp, K., Franzluebbers, A.J. 2022. Managing grasslands to optimise soil carbon sequestration. In: Rumpel, C., editor. Understanding and fostering soil carbon sequestration. United Kingdom: Burleigh Dodds Science Publishing Limited. Chapter 18.
Franzluebbers, A.J., Poore, M.H. 2022. Soil fertility characteristics in North Carolina pastures as affected by spatial separation and renovation with annual forages. Agronomy Journal. 115:384-394. https://doi.org/10.1002/agj2.21218.
Franzluebbers, A.J., Shoemaker, R., Cline, J., Lipscomb, B., Stafford, C., Farmaha, B.S., Daniel, J., Waring, R., Lowder, N., Thomas, W.E., Poore, M.H. 2022. Nitrogen fertilizer recommendations can be adjusted for soil health condition. Agricultural and Environmental Letters. 7:e20091. https://doi.org/10.1002/ael2.20091.
Franzluebbers, A.J., Martin, G. 2022. Farming with forages can reconnect crop and livestock operations to enhance circularity and foster ecosystem services. Grass and Forage Science. 77:270-281. https://doi.org/10.1111/gfs.12592.
Franzluebbers, A.J. 2022. Probing deep to express root-zone enrichment of soil-test biological activity on southeastern U.S. farms. Agricultural and Environmental Letters. 7:e20087. https://doi.org/10.1002/ael2.20087.
Franzluebbers, A.J. 2023. Soil organic Carbon and Nitrogen storage estimated with the root-zone enrichment method under conventional and conservation land management across North Carolina. Journal of Soil and Water Conservation. 78:124-140. https://doi.org/10.2489/jswc.2023.00064.
Franzluebbers, A.J. 2022. Soil-test biological activity associates with soil aggregation characteristics under different land uses in North Carolina. Soil Science Society of America Journal. 86:1639-1651. https://doi.org/10.1002/saj2.20474.
Mashaheet, A., Burkey, K.O., Marshall, D. 2023. The interaction of O3 and CO2 concentration, exposure timing and duration on stem rust severity on winter wheat variety ‘Coker 9553’. Environmental Pollution. 334:122122. https://doi.org/10.1016/j.envpol.2023.122122.
Franzluebbers, A.J. 2021. Paired land-use assessment of soil organic C and N in the root zone of agricultural systems. Soil Science Society of America Journal. 85:1785-1798. https://doi.org/10.1002/saj2.20290.
Zhang, K., Zentella Gomez, R., Burkey, K.O., Liao, H., Tisdale, R.H. 2022. Microbial community dynamics responding to nutrient allocation associated with soybean cultivar ‘Jake’ ozone adaptation. Science of the Total Environment. 864:161008. https://doi.org/10.1016/j.scitotenv.2022.161008.