Final report for LS18-303
Project Information
The experimental framework of the original Farming Systems Research Unit (FSRU) will continue: replicated plots of farming systems managed with farm-scale equipment. We are also merging the agroforestry research experiment within this large-systems research effort, since there is complementarity in long-term nature, similar soil types, soil health evaluation procedures, design of timber production and shade for animals as part of both systems, and evaluation of forage and cattle production as part of some agro-ecosystems. Within this context, new research questions have emerged. How do perennial production systems compare with annual production systems? How does grazing affect botanical composition of pastures compared with various hay management strategies? Can shade be a significant ecosystem buffer for livestock production in the southeast US? What are the soil health impacts of integrated crop-livestock systems and pasture grazing compared with more traditional annual cropping systems? Are timber species more important on certain soil types and can timber species impact other ecosystem services? Are conventional and organic nutrient amendment strategies having an effect on soil health metrics? Do farmers have reliable and/or reasonable options for making selection of sustainable farming practices that do not meet mainstream standards? In this proposal, we have attracted several new researchers to CEFS who have fresh ideas on relating this experiment to the sustainability issues of our time. Some of the new issues were never envisioned when the experiment was first designed. Our research team will be able to provide answers to many of the emerging issues on agricultural sustainability through the continued efforts focused on these long-term systems studies.
- How systems impact long-term sustainability of soil and water resources;
- System differences in resilience to perturbations in weather, inputs and market prices; and
- How systems impact biodiversity, pest dynamics and ecological services of agriculture.
Research
Farming systems for the future need to consider both high productivity potential and safeguarding the environment by limiting nutrient losses, rebuilding soil biological activity and diversity, and creating ecological balance. The Farming Systems Research Unit (FSRU) and agroforestry research experiment are exploring alternative management approaches to production that can provide insights to long-term sustainability of systems, not just short-term returns. Our approach is to measure production and environmental variables over time in these diverse systems so that realistic expectations can be delivered to producers on quantity and quality of production, diversity of economic opportunities offered by production systems, nutrient input requirements, soil health changes, animal impacts on soil and water resources, and illustrative interactions among components that shed light on how to better design agro-ecosystems for the future.
Historical production data from the first 25 years of FSRU implementation were assembled to characterize the diversity and level of production of various systems under continuous evaluation. Production data will be compared with soil resource conditions as an assessment of soil health changes associated with specific types of management. These production and environmental quality data will be combined into a systems evaluation that can be viewed from both economic and ecological perspectives.
Collaborations are anticipated with all other members of the research team to combine perspectives of production, economics, and environmental quality.
At the FSRU and Agroforestry Research Experiment, we have successfully carried out all the field activities to ensure the continuation of the project and followed protocols to guarantee that the data generated is accurate. It has been almost 25 years since the beginning of the project, and our plan is to continue providing outcomes for a better understanding of the long-term effects that different agroecosystems can have on the productivity and the environment. Most successful long-term experiments need periodic changes to improve or to adjust to new realities and our project is not the exception. Starting in spring 2021, we had several meetings to discuss possible changes in the experiment. Considerations for these changes included:
- Fewer treatments (9 compared with 14) with common crop rotation cycles among all cropping treatments.
- More realistic farming systems with a gradient from simple, contemporary systems (conventional) to more ecologically complex systems.
- Focus on key management approaches among a diversity of farming styles.
- Desire to simplify management, despite the complexity of such a large and complicated experiment.
- Approach to focus on realistic production output through grain, forage, and cattle components among systems of the experiment.
The implementation of the new treatment approaches started in fall 2021 as follows:
|
Treatment |
New approach |
|
Organic-legume |
Organic cash grain with legume N input |
|
Organic-livestock |
Organic integrated crop-livestock with grazing and manure inputs. |
|
Tilled-conventional |
Changed to full tillage with winter annual weeds and no planted cover crops |
|
Conventional no-till with cover crops |
Changed to full conservation approach with multi-species winter cover crops and planting green in the spring |
|
Pasture-crop rotation phase 1 |
The rotation cycles changed to be in 4-year phases to match cropping systems in both conventional and organic treatments, and simplified so that cropping will appear every year in one of the three treatment rotations. |
|
Pasture-crop rotation phase 2 |
|
|
Pasture-crop rotation phase 3 |
|
|
Silvopasture |
Convert timber plots to a common silvopasture treatment, designed with permanent fencing around all four species of trees within a replication and planted with native warm season grasses. |
|
Successional |
This treatment remains the same. |
Greenhouse gas emissions – Wayne Robarge
Relatively large uncertainty in the measurement of greenhouse gas emissions (especially nitrous oxide, N2O) from agroecosystems is due to both temporal and spatial variability. During the past several years, we have made a concerted effort to address the question of temporal variability in emissions of N2O from typical cropping systems (e.g. conventional and no-till corn). We now have a relatively straightforward, robust system in place and have observed the temporal pattern (24 hr, 7 days a week) in N2O emissions across two growing seasons. We are now confident in our ability to track the temporal pattern in emissions at several locations within a given experimental design, revealing patterns in emissions in response to management and weather (e.g. rainfall events) not possible with traditional static chamber measurements. With this capability now in place, we will move forward to: (a) better inform quantitative measurements of N2O emissions from different cropping systems using our temporal measurements to supplement the traditional static chamber approach and (b) exploit our ability to track temporal patterns in emissions to inform/guide more process-based investigations on N-cycling with other cooperators (e.g. Shuijin Hu). We will continue to integrate better the observed temporal pattern in emissions with our continued use of static chamber measurements to assess cumulative emissions of N2O from various cropping systems. At the same time, we will expand our collection of ancillary data to better inform modeling efforts to predict emissions. Possible partners in this effort include the Environmental Defense Fund, who have similar interests in identifying cropping systems in the southeastern US that improve nutrient use efficiency and reduce greenhouse gas emissions, such as N2O. We have already submitted a proposal to the USDA-NIFA Organic Transitions program in which we incorporate our unique ability to track gas emissions almost in real-time to guide sampling/interpretation of more process-based research regarding changes in microbial populations and N cycling. Lastly, we will continue to present results from our work to various stakeholders as well as through the more traditional scientific outlets.
Rural sociology – Dara Bloom and Sarah Bowen
In the last grant cycle, we conducted interviews with 18 grain farmers to explore whether their decision to adopt organic practices and/or certification was affected by access to land, or the terms of their lease. Qualitative data gathered and analyzed resulted in a set of potential factors that influence farmers’ decision making regarding sustainability practices and organic certification. While lease terms were of concern for farmers near an urban center, a wider set of issues (including weed management) appeared to affect their decisions. In the next phase of research, we will test the factors identified in this small sample by conducting a broad survey of farmers across North Carolina to query their environmental and conservation practices and specific issues affecting their decision-making. The survey will be designed with the assistance of a graduate student in the Sociology and Anthropology Department, and will be pilot tested before being sent out through CEFS and Extension listservs. Analysis of this survey will lead to reports that will be shared at relevant conferences. In the second year of this grant cycle, we will collaborate with Alan Franzluebbers to identify adoption barriers regarding farmer adoption of conservation practices and/or biological soil testing. We will use a sociological frame to address issues related to farmer motivation for adopting certain practices that other researchers on this grant are attempting to disseminate. We will use an adoption and diffusion approach to analyze farmer motivations and disincentives for adoption. We will conduct qualitative methods with a sample of farmers, and then choose three farms from the population to develop case studies that can be disseminated to promote further adoption of these methods.
Small-scale organic farming economics – Kathleen Liang
Small-scale and limited-resource farmers face growing challenges in pursuing organic production. Although many farmers are still committed in commercial crops such as corn and soybean, there is an increasing trend for farmers to diversify their production to include mixed vegetables and other specialty crops. There has been very limited research on farm financial feasibility and efficiency in mixed-scale, mixed-crop organic operations. The next phase of this research will focus on gathering consistent and reliable data from on-farm simulations in organic certified fields.
The research approach will focus on mixed vegetables planted on certified organic field starting in March (Spring season) and going through December (Summer and Fall seasons). A variety of organic practices will be tested and applied to control weeds, pests, and other factors that mimic real farm challenges in organic operations. Detailed data of labor hours by tasks, irrigation water usage, other inputs, and harvest amount will be gathered and recorded daily. All data will be entered into a farm financial analysis package, which will produce cash-flow statement, income statement, and balance sheet to reflect farming budget and outputs.
Publications will include extension reports, peer reviewed journal articles, and training manuscripts for extension agents to work with producers. Information will also be presented in professional conferences, farm meetings, and extension meetings. Collaborators will include NC Cooperative Extension members and national eXtension working groups.
Soil biogeochemical cycling – Shuijin Hu
Multiple field, greenhouse, and lab experiments have examined N dynamics and N2O emissions from organic and conventional systems located at the FSRU.
We plan to intensively examine how farming practices (conventional and organic) affect N-transforming microbes in the FSRU. We hypothesize that long-term organic farming, when appropriately managed, may induce consistent and predictable changes in the N-cycling microbes and foster the development of the soil microbial community with high N use efficiency (i.e., high N retention in plants or soil and low N2O production). A Ph.D. student and visiting scholars will undertake this task. The student is supported by a Teaching Assistantship in Biology and the funds requested in this proposal will support this research. We have two major objectives:
1) Characterize the effects of conventional and organic farming on N-cycling microbes in field plots at the FSRU. Few experiments have characterized the abundance and community structure of N-cycling microbes in response to different farming practices in US coastal plain soils. Because many denitrifying microbes are widely phylogenetically distributed, analysis of metabolic (functional) genes coding for specific enzymes along the denitrification pathway provides an effective approach to quantify the size of related functional guilds. Real-time PCR will be used to quantify the functional genes of ammonia-oxidizing microbes (amoA for AOA and AOB) and denitrifiers (nirS, nirK and nosZ genes).
2) Identify the primary driving factors that modulate the effect of farming practices on N-cycling microbes. We plant to quantify diverse soil factors that may affect the composition and activities of N-cycling microbes such as altered C and N availability and soil pH. Structural equation model analysis will be used to identify the primary driving factors that control the abundance of N-cycling microbes and ratios of different denitrifier groups.
Soil ecology and management – Alan Franzluebbers
Soil functioning is a critical issue when evaluating the sustainability of agro-ecosystems. If soil functions cannot be sustained, then high production cannot be expected. Soil chemical, physical, and biological aspects of soil functionality are important. Some key soil functions of importance in agro-ecosystem management are supporting plant and animal production, regulating water infiltration, storage, and delivery to plants, effective cycling of nutrients, supporting animal and equipment traffic on the land, and supporting biodiversity to overcome environmental stresses.
Soil health evaluation will be conducted regularly over time from the FSRU and agroforestry research experiments by collecting soil from surface depths (e.g. 0-6, 6-12, and 12-20 cm). Multiple depths are important to understand the stratification of total, particulate, and biologically active C and N fractions, as they develop over time with conservation management. Total organic C and N will be determined with dry combustion, particulate organic C and N will be determined from the sand fraction following dispersion, soil microbial biomass C will be determined by chloroform fumigation-incubation, potential C and N mineralization will be determined from aerobic incubation over 24 days, and inorganic nutrients will be determined from routine soil extractions using soil-testing approaches. Soil bulk density will be determined from dry weight and volume of soil cores. Soil aggregation will be periodically determined and C and N protected within aggregates evaluated as a mechanism of organic matter storage.
We expect to obtain soil health data that will be widely divergent among management systems evaluated due to the differences in nutrient application, tillage, and nature of plant communities. Data will also continue to be collected from the pasture to crop transition in the previous funding period. Data will be assembled into stand-alone research publications, but also archived for utilization in long-term production and environmental quality evaluations.
Soil health evaluation – Alex Woodley
Soil fertility is an important issue of sustainability for organic production systems. Soil health is a topic of increasing public interest and concerted efforts are underway across the country to provide nationally standardized metrics on defining soil health and how soil health is tied to productive agroecosystems. Many of the soil health metrics have emerged from the Midwest and northeastern US, which generally have high organic matter soils and are not as weathered as southeastern soils. Therefore, the FSRU will be an essential location for soil health analysis for the southeastern US to determine if soil health evaluations can be standardized nationally or need to be considered on a regional basis. The long-term nature of the field site coupled with the diverse farming systems allows for in-depth analysis of the impacts of management practices on soil health parameters over time. The proposed research will utilize archival soil samples and early yield data to generate a baseline on a variety of crop and soil parameters (e.g. total soil carbon/nitrogen, particulate organic matter, pH, aggregate stability and potentially mineralizable N). In 2019-2021, a rigorous soil sampling program will be initiated in all the FSRU units and the same parameters will be analyzed for a temporal comparison. In addition, for parameters that require fresh soil samples a comparative analysis will be completed between farming units and within farming units (e.g. microbial biomass, water extractable organic matter, soil-test biological activity). This information will be used to determine the sensitivity of the soil biochemical parameters to changes over time as well as changes between management practices, in these relatively low soil organic matter soils of the Southeast. A second component of this research is connecting accepted soil health parameters to productive agroecosystems. An analysis of crop yield stability over time will be compared to changes in soil health/quality with the hope that crop resilience, for example during periods of drought, can be attributed to soils that have been measurably improved through various best management practices. This research will be presented at national meetings and published in relevant peer-reviewed journals. The data generated will be of interest to soil conservation groups as well as NGO’s such as the Soil Health Institute.
Weed ecology and management – Ramon Leon
Weeds are an important component of agroecosystems not only due to the crop yield losses they cause, but also their role in favoring biodiversity. Different systems at the FSRU have created distinct weed communities and weed population dynamics that influence their management and sustainability. However, limited research has been conducted on weed ecology and management at FSRU. We propose characterizing weed seed bank dynamics focusing on demographics and diversity to determine how each farming systems affects weed populations in the short and long term. This information will help growers better design effective weed management strategies while reducing their environmental impact.
Seed bank samples will be collected every spring to quantify weed seed density and weed community composition. Germinable seed bank analysis will be done under greenhouse conditions. Also, “pulse” studies in which weed seed rain will be simulated in specific locations, and seed survival and resulting population dynamics will be tracked over time. This will indicate which system is more resilient to weed invasion. Furthermore, associations between soil microbial communities and weed seed survival will be studied.
Results will be published in peer-reviewed journals such as Weed Science, Weed Research, Agronomy Journal, and Agriculture, Ecosystems and Environment. Also, findings will be shared with the scientific community in conferences and with the general public and producers in field days.
It is anticipated that the proposed research projects will generate collaborations with Dr. Alex Woodley and Dr. Chris Reberg-Horton to integrate soil and cover cropping management components and with Dr. Wei Shi and Dr. Shuijin Hu to study soil microbial effects on weed seed banks.
The collaborating scientists have mixed results and outcomes in their reporting structure so for consistency we have left them together in the outcomes section.
Educational & Outreach Activities
Participation Summary:
Year 8 annual report:
- Duke Immerse Program “Imagining-future-food”, Nov 4, 2021, 10, Undergraduate senior students in Biology/ENV to know about the farming systems.
- High Tunnel Operation and Financial Preparation, New and Beginning Farm Training, (121 participants)
- Financial analysis for beginning farmers, AGVET Meet and Greet meeting, (15 participants)
- Growing Specialty Vegetables for Ethnic Markets, Extension Extended training series, 25 participants)
- Farm record keeping, web-training, (19 participants)
- MarketMaker Sign-up training, web-training, (28 participants)
- Collaborative Farming/Multifarm Direct to Consumer Marketing – Food Hub models, (56 participants)
- Collaborative Farming/Multifarm Direct to Consumer Marketing – Food Hub models, (62 participants)
- Liang, C. (2020). Flamer weeding demonstrations, Greensboro (5 participants) NCA&T Farm and Goldsboro (18 participants) Cherry Research Farm, NC.
- Liang, C. (2020). Whitaker Small Farm Group and Soldiers in Ag training, transplant production and harvesting, Small Farm Unit, Goldsboro, NC. (28 participants)
- Liang, C. (2020). Farm financial analysis overview, Moore County Extension office, (5 participants)
- Liang, C. (2020). Farm financial benchmarking and budget, AgriShop, Bladen County Extension office, (6 participants)
- Liang, C. (2020). Growing your own garden and specialty vegetables, Wayne County Library, Goldsboro, NC. (29 participants)
- Liang, C. (2020). Farm financial analysis using FINPACK, Durham County Extension office, (4 participants)
- Liang, C. (2020). High Tunnel training workshop. Goldsboro, NC. (36 participants)
- Liang, C. (2020). Soldiers in Ag program, Small Farm Unit harvesting, (18 participants)
- Liang, C. (2020). Diversified farm financial analysis, Sampson County Extension office, January 9. (18 participants)
Year 9 Final Report:
- Soil Science class , Nov 13, 2022, 10, Undergraduate to know about the project and greenhouse gas emissions.
- ASPIRE interns , June 17, 2022, 20, Undergraduate students on various degrees to know about the systems experiment.
- NCSU Advance Agroecology class , April 6, 2022, 23, Both undergraduate and graduate students to know about the farming systems.
- Duke Immerse Program “Imagining-future-food”, Nov 4, 2021, 10, Undergraduate senior students in Biology/ENV to know about the farming systems.
- High Tunnel Operation and Financial Preparation, New and Beginning Farm Training, (121 participants)
- Financial analysis for beginning farmers, AGVET Meet and Greet meeting, (15 participants)
- Growing Specialty Vegetables for Ethnic Markets, Extension Extended training series, 25 participants)
- Farm record keeping, web-training, (19 participants)
- MarketMaker Sign-up training, web-training, (28 participants)
- Collaborative Farming/Multifarm Direct to Consumer Marketing – Food Hub models, (56 participants)
- Collaborative Farming/Multifarm Direct to Consumer Marketing – Food Hub models, (62 participants)
- Liang, C. (2020). Diversified farm financial analysis, Sampson County Extension office, January 9. (18 participants)
- Liang, C. (2020). Flamer weeding demonstrations, Greensboro (5 participants) NCA&T Farm and Goldsboro (18 participants) Cherry Research Farm, NC.
- Liang, C. (2020). Whitaker Small Farm Group and Soldiers in Ag training, transplant production and harvesting, Small Farm Unit, Goldsboro, NC. (28 participants)
- Liang, C. (2020). Farm financial analysis overview, Moore County Extension office, (5 participants)
- Liang, C. (2020). Farm financial benchmarking and budget, AgriShop, Bladen County Extension office, (6 participants)
- Liang, C. (2020). Growing your own garden and specialty vegetables, Wayne County Library, Goldsboro, NC. (29 participants)
- Liang, C. (2020). Farm financial analysis using FINPACK, Durham County Extension office, (4 participants)
- Liang, C. (2020). High Tunnel training workshop. Goldsboro, NC. (36 participants)
- Liang, C. (2020). Soldiers in Ag program, Small Farm Unit harvesting, (18 participants)
Learning Outcomes
Project Outcomes
1) Soil and its microbial inhabitants are vital to ecosystem functioning. A scientist from USDA-Agricultural Research Service assembled recent scientific information into a revised textbook on soil microbiology. Sections covered in this chapter on carbon transformation and soil organic matter formation included (1) significance of soil organisms to global, field-level, and root-level carbon cycling. (2) organic matter inputs and characteristics from plants, composts, agricultural byproducts, and industrial byproducts. (3) organic matter decomposition as a function of soil microbial biomass, diversity, and activity, and environmental factors, and its influence on soil health. (4) beneficial properties of soil organic matter, factors influencing soil organic matter, and management effects on soil organic matter. This textbook is expected to be used by a variety of universities throughout the country.
Source: Franzluebbers, A.J. (2021) Chapter 14: Applied aspects of soil carbon. In: Principles and Applications of Soil Microbiology, 3rd Edition, Elsevier.
2) 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 in Raleigh North Carolina collaborated with a scientist from 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.
Source: 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.
3) Soil-health conditions are improved with diverse agricultural enterprises
Long-term agricultural experiments are an invaluable resource to better understand how management affects soil conditions, as well as how persistent soil, weather, and management conditions affect productivity, profitability, and environmental quality. A scientist from USDA-Agricultural Research Service in Raleigh, North Carolina collaborated with investigators at North Carolina State University to investigate the influence of 19 years of management on soil organic matter and soil biological activity. Conservation agriculture approaches using no tillage, grass-crop rotation, cover cropping, and organic amendments resulted in superior soil attributes for enhancing soil health conditions on a large field-scale experiment in Goldsboro NC. Managed timber and agricultural abandonment improved soil organic carbon near the soil surface, which allowed significant protection of the soil from erosion and offered opportunities for nutrient retention. However, 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. This information will be valuable for farmers and extension agents to design robust and resilient agricultural management systems in the face of growing threats from climate change.
Core ideas:
- Plantation forestry had greater surface residue carbon and nitrogen than cropping systems
- Crop-livestock and organic systems had greater soil carbon and nitrogen than conventional systems
- Reduced tillage was more important for soil carbon and nitrogen than cover cropping with tillage
- Forage-based rotations, limited tillage, and organic inputs benefited soil carbon
Source: Franzluebbers, A.J., Reberg-Horton, S.C., & Creamer, N.G. (2020). Soil carbon and nitrogen fractions after 19 years of farming systems research in the Coastal Plain of North Carolina. Soil Science Society of America Journal, 84, 856-876.
4) Arbuscular mycorrhizal fungi (AMF) shifted community composition of N-cycling microbes and suppressed soil N2O emissions in both conventional and organic farming systems. Utilizing conventional (CONV) and organically managed (OM) soils from our long-term Farming Systems Research Unit (FSRU), we examined how plant roots and AMF affect N2O emissions, N2O-producing (nirK and nirS) and N2O-consuming (nosZ) microbes under normal and high N inputs. Our results showed that high N input increased soil N2O emissions and the ratio of nirK to nirS microbes. Roots and AMF did not affect the (nirK + nirS)/nosZ ratio but significantly reduced N2O emissions and the nirK/nirS ratio. They reduced the nirK/nirS ratio by reducing nirK-Rhodobacterales but increasing nirS-Rhodocyclales in the CONV soil while decreasing nirK-Burkholderiales but increasing nirS-Rhizobiales in the OM soil. Our results indicate that plant roots and AMF reduced N2O emission directly by reducing soil N and indirectly through shifting the community composition of N2O-producing microbes in N-enriched agroecosystems, suggesting that harnessing the rhizosphere microbiome through agricultural management might offer additional potential for N2O emission mitigation.
Zhang, X., Qiu, Y., Gilliam, F.S., Gillespie, C.J., Tu, C., Reberg-Horton, S.C. and Hu, S., 2022. Arbuscular Mycorrhizae Shift Community Composition of N-Cycling Microbes and Suppress Soil N2O Emission. Environmental Science & Technology, 56(18), pp.13461-13472.
5) A vision is articulated to align agricultural production with environmental goals
The future of humanity and how agriculture can continue to support the food and fiber needs of a burgeoning population is threatened by agriculture’s persistent negative effects on the environment. The essential natural resources that will be needed in increasingly greater capacity are being undermined from contemporary 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 that manage agricultural systems in harmony with nature, not against her. This commentary provides a message that we should be seeking healing of our planet, not just less harm than in the past. It’s an important distinction that needs to be considered for the future health of the people and the planet. Core ideas:
- Vital natural resources to sustain agriculture are being
- undermined by the contemporary system
- Solutions to manage our food and environmen-tal dilemma require
- an agroecological approach
- Our focus needs to be on healing our planet, not just doing less
- harm than in the past
Source: Franzluebbers, A.J., Wendroth, O., Creamer, N.G., & Feng, G.G. (2020). Focusing the future of farming on agroecology. Agricultural & Environmental Letters, 5, e20034.
6) Micrometeorological changes under silvopasture management are important, but not very large
Silvopasture systems can be a sustainable management approach for environmental stressful locations in the southeastern US with sandy soils and yet abundant precipitation. Pasture management and livestock well-being are thought to be improved, but limited data exists to make quantitative recommendations to producers. A scientist from USDA-Agricultural Research Service collaborated with scientists from North Carolina State University to quantify the effects of tree species and location within an alley-based silvopasture system on light penetration, forage growth, and nutritive value of forage. Dense tree canopies reduced light penetration, but since lines of trees were alternated with alleys of forage, cattle had access to abundant forage. Air temperature and temperature-humidity index were reduced in shaded positions. Seasonal effects of shade were more evident with deciduous tree canopy than evergreen tree canopy. This research will help support development of more sustainable ruminant livestock production systems in the warm, humid southeastern US region.
Core ideas:
- Understory forage yield and quality were not affected by tree species, except at one sampling point
- Differences in tree species did not affect changes in microclimatic conditions
- Microclimatic changes under trees were prominent during summer in the daytime
- Results highlight the extent of tree-induced changes in temperature, humidity, and forage productivity
Source: Castillo, M.S., Tiezzi, F., & Franzluebbers, A.J. (2020). Tree species effects on understory forage productivity and microclimate in a silvopasture of the southeastern USA. Agriculture, Ecosystems and Environment, 205, 106917.
7) Estimation of soil biological health is affected by choice of laboratory protocol Soil health is an important concept that has gained strong traction within the farming community. Biological indicators of soil health are the most controversial due to a variety of approaches being used without sufficient calibration. Scientists from the USDA Agricultural Research Service in Raleigh NC and Columbia MO collaborated on a project to evaluate two different soil biological activity protocols. Soils from two long-term field experiments comparing a wide range of management conditions in Missouri and North Carolina were tested. Both biological activity protocols gave results that were highly related across a large gradient, but results differed in obvious ways based on differences in specific steps. Although quick soil-test methods are desirable, they still need to adhere to basic principles of analysis. We showed that alternative methods to estimate soil biological activity need to give due attention to temperature and water conditions during incubation. Unnecessary variations or spurious results could otherwise be produced, which are problematic in making interpretations for farmers. Soil-test biological activity is an important attribute of soil health, and although a variety of methods could be possible, some standardization is needed for sound evaluations.
Core ideas:
- Deviations in standard operating protocol cause undesired variations in the flush of CO2
- Temperature and soil water content must be carefully controlled in respiration analyses
- A standard approach to measuring the flush of CO2 is available and should be deployed
Source: Franzluebbers, A.J., & Veum, K.S. (2020). Comparison of two alkali trap methods for measuring the flush of CO2. Agronomy Journal, 112, 1279-1286.
8) Short-term changes in soil-test biological activity due to root growth are prominent
Living soil breathes! This life can be detected from the carbon dioxide emitted from soil through the actions of soil microorganisms decomposing organic matter. Interest in determining soil biological activity is growing, because of soil health enthusiasm by farmers and various stakeholders devoted to regenerative agriculture. An ARS scientist in Raleigh North Carolina collaborated with a visiting scientist from the Federal Technical University of Parana in Brazil to test how much soil-test biological activity changes in response to sampling during a growing crop.
Short-term effect of root development in soil was relatively minor (7%) compared with much greater long-term effects from edaphic factors promoted by long-term management (81%). Results indicate that short-term changes in soil-test biological activity are important, but modest compared with variations due to edaphic factors of soil depth and texture. These results will help users of soil-health testing to understand the extent of soil biological changes that can be expected during different sampling periods within the year.
Core ideas:
- Plant root development feeds soil-test biological activity (STBA)
- Both short- and long-term C inputs affect STBA
- STBA increased by 53 ± 25% following several weeks of test-crop
- growth
Source: Franzluebbers, A.J., & Assmann, T.S. (2020). Soil-test biological activity with short-term and long-term carbon contributions. Agricultural & Environmental Letters, 5, e20035.
9) Analysis of surface residues is now easier to quantify Conservation agricultural systems promote surface residue cover of the soil. Estimating the mass of surface residues is complicated by contamination with soil. A scientist from USDA-Agricultural Research Service in Raleigh NC developed an estimation procedure based on routine analysis of samples for carbon concentration. The ash fraction of surface residues and pasture forage biomass was highly negatively associated with carbon concentration of samples. Therefore, as carbon concentration declines below a theoretical level of 45%, great likelihood exists that the sample is contaminated with soil. The equation developed had very low deviation, suggesting that carbon concentration alone would be an effective method to replace the additional analysis of ash fraction. These results will be particularly useful for soil and plant scientists studying agricultural systems with conservation management approaches and should lead to better scientific understanding of how management impacts soil and environmental quality.
Core ideas:
- Soil contamination can be predicted from total C concentration f a plant sample
- Ash and C concentrations were negatively associated across a diversity of sample types
- Little practical difference existed among plant sources in the association between ash and C concentrations
- Plant biomass can be corrected for soil contamination knowing C concentration
Source: Franzluebbers, A.J. (2020). Carbon concentration predicts soil contamination of plant residues. Agricultural & Environmental Letters, 5, e20037.
10) Small-scale organic farming
- Observed and documented the growth of Asian Specialty Vegetables through average and adverse conditions
- Studied the effects of growing small fruit gourds in manipulated environments
- Collected soil temperature data to observe heat variation when using black plastic
- mulching
- Designed a cookbook to help introduce Asian Specialty Vegetables into American style cuisine
- Began construction of an SFU Training Manual for new employees
- Created equipment logs to document use and maintenance
11) Weed ecology and management
As part of CEFS efforts to develop sustainable production systems, the weed science program has been studying how crop management intensity affects weed community dynamics in conventional as well as low-input systems. During the last few years, we determined the importance of diversifying weed control tools and management strategies to maintain weed community diversity in the system. The data generated demonstrated how over-simplified strategies favor the increase in the populations of weed species that are more aggressive and difficult to control, such as Amaranthus palmeri (Palmer amaranth) and Eleusine indica (goosegrass). Furthermore, we developed systems to use variable planting in row crops to increase weed suppression while reducing herbicide dependence and maintaining production costs for growers.
We also analyzed how different stakeholders prioritize weed management decisions based on risk perceptions. This was done through a case-study in which CEFS faculty were directly involved. This study showed how there is a strong perception, especially among regulators, that synthetic pesticides are more effective than integrated management approaches, and this perception is not easily changed even when direct data demonstrating weed population reductions is provided. Liability concerns as well as ease of implementation are major drivers of for the selection of weed control tools.
- Ethridge SR, Locke AM, Everman WJ, Jordan DL, Leon RG (2022) Crop physiological considerations for combining variable density planting to optimize seed costs and weed suppression. Weed Science 70:687-697 https://doi.org/10.1017/wsc.2022.62
- Leon RG, Creamer N, Reberg-Horton SC, Franzluebbers AJ (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 Management 15:152-159
- Oreja FH, Inman MD, Jordan DL, Vann M, Jennings KM, Leon RG (2022) Effect of cotton herbicide programs on weed population trajectories and frequency of glyphosate-resistant Amaranthus palmeri. Weed Science 70:587-594
- Oreja FH, Inman MD, Jordan DL, Bardhan D, Leon RG (2022) Modeling weed community diversity based on species population density dynamics and herbicide use intensity. European Journal of Agronomy 138:126533
- Ethridge SR, Locke AM, Everman WJ, Jordan DL, Leon RG (2022) Response of maize, cotton, and soybean to increased crop density in heterogenous planting arrangements. Agronomy 12:1238 doi.org/10.3390/agronomy1201238
- Oreja FH, Inman MD, Jordan DL, Leon RG (2021) Population growth rates of weed species in response to herbicide programme intensity and their impact on weed community. Weed Research 61:509-518 https://doi.org/ 10.111/wre.12509
- Dhamankar, S. S., Hashemi-Beni, L., Kurkalova, L. A., Liang, C. L., Mulrooney, T., Jha, M., Monty, G., & Miao, H. (2020). Study of active farmland use to support agent-based modeling of food deserts, Int. Arch. Photogramm. Remote Sens. Spatial Inf. Sci., XLIV-M-2-2020, 9–13, https://doi.org/10.5194/isprs-archives-XLIV-M-2-2020-9-2020. https://www.int-arch-photogramm-remote-sens-spatial-inf-sci.net/XLIV-M-2-2020/9/2020/
- Brown, S., & Liang, K. (2020). Telefarming: When Push Comes to Shelve in Responding to COVID-19. Journal of Agriculture, Food Systems, and Community Development, 9(3), 1-4. https://doi.org/10.5304/jafscd.2020.093.030
- Ashqer, Y. S., Liang, C. and Bikdash, M. (2020). Creating a Multivariate-Multifunctional Database for Weed Control to Support Organic Mixed Vegetable Production, World Journal of Agriculture and Soil Science, ISSN: 2641-6379. Available online https://irispublishers.com/wjass/pdf/WJASS.MS.ID.000596.pdf
12) Greenhouse gas emissions
Woodley and Robarge expanded their automated chambers to 16 and are using this capacity to assess the impact of climate smart practices on soil health and soil carbon sequestration. In one long-term no-till plot we initiated a study in 2021 where large quantities of biochar and leaf litter based compost were added to the plots in a single application, additional treatments included no amendment with nitrogen fertilization and a control with no fertilization. In 2021, sorghum was grown and nitrous oxide and carbon dioxide were measured. There was no yield impact of the carbon input. Nitrous oxide was not influenced by the additions with only the control with lower emissions. Emission factors were not influenced. In 2022, corn was grown and like in 2021, no impact on yield and comparable emissions. This study will continue and conclude in 2023. Soil health parameters will be measured during and at the end of the 3 years to determine the potential for these inputs to improve soil functionality. These are complementary studies (same treatments) occurring at two other research stations in the coastal plain on similar soils to provide 9 site years of data on these questions. This sites are only measuring soil health and not the GHG component. Dr. Rejesus an agricultural economists is collaborating on the economic viability of these carbon strategies.
Conference Proceedings:
Woodley, A.L., W. Robarge, H. Carvalho. (August 2022). Trade-offs or co-benefits of carbon input strategies on greenhouse gas emissions in low organic matter soils of the Southeast U.S. Worlds Soils Conference. Glasgow, Scotland