Location: Southeast Watershed Research
2021 Annual Report
Objectives
Objective 1. Develop diversified rotational cropping systems for an integrated crop-livestock production system that includes mixed cropping, provide year-round vegetative cover, habitat for arthropod natural enemies and pollinators, and mitigate crop metal toxicity and persistence of antimicrobial resistance.
Sub-objective 1.1. Compare G x E x M effects (where G is taken as crop diversity/rotation – not genetic engineering) on crop productivity and soil and forage quality in a small integrated crop-livestock farming system setting of: 1). An aspirational rotational cropping system that includes summer cotton (Gossypium hirsutum L.), peanut (Arachis hypogaea), summer and winter forages, and a winter oil-rich biofuel feedstock cash crop, in a full year companion cropping system with phosphorus need-based broiler litter fertilization, and reduced tillage under irrigated and dryland conditions (ASP); 2). A business as usual rotational cropping system that includes summer cotton-peanut-corn (Zea mays L.) with a winter rye (Secale cereale) cover crop that is chemically killed and allowed to decompose on the soil surface, with nitrogen need-based broiler litter fertilization, and reduced tillage under irrigated and dryland conditions (BAU-1); and 3). A business as usual rotational cropping system that includes summer cotton-peanut-forage with a winter rye cover crop that is hayed as forage, with nitrogen need-based broiler litter fertilization, and reduced tillage under irrigated and dryland conditions (BAU-2).
Sub-objective1.2. Incorporate native wildflowers in margins of fields in Sub-Objective 1.1 and assess effects on enhancing pest arthropod natural enemies and attracting pollinators.
Objective 2. Develop and test management strategies for an integrated crop-livestock production system that incorporates flue gas desulfurized gypsum (FGDG) with broiler litter (BL) in southeastern cropping systems to reduce phosphorus (P), nitrogen (N) and metals loss in runoff, manage subsoil acidity, and reduce persistence of resistance to antimicrobial agents.
Sub-objective 2.1. Compare the effects of FGDG and FGDG + BL on crop yield; P, N, and metals loss in runoff; subsoil acidity; and SOM composition.
Sub-objective 2.2. Compare the persistence of foodborne pathogens and bacteria with resistance to metals and antibiotics in cropping systems.
Objective 3. Evaluate and quantify farm-level economic and ecosystem services benefits and risks associated with the use of broiler litter, flue gas desulfurized gypsum, and field edge arthropod habitat buffers for southeastern crop-livestock production systems.
Sub-objective 3.1. Develop a five-year multi-practice planning scenarios using a cooperator’s farm (Wilson Farm WF) as a case study that compares net sustainable profit from Objective 1 cropping systems given the producer’s profit versus environmental goals.
Sub-objective 3.2. Forecast cropping systems effects on runoff losses of water, sediment, C, N, P, S, and metals.
Sub-objective 3.3. Integrate producer’s production, profit, and environmental goals to develop land use designs that optimize producer-desired outcomes.
Approach
The overall goal of this project plan is to develop an integrated production system that provides increased flexibility for small-farm crop-livestock producers to diversify their production portfolio by enhancing the sustainability of ecosystem services delivered from landscapes owned or rented by their operation. We will implement plot-scale research to calibrate crop, environmental, geospatial, economic and whole-farm planning models to compare the performance potential of three enterprise scenarios over a five-year planning cycle. Project objectives will focus on six core subsystems affecting the sustainability of small Crop-livestock producers (Soils, Crops and Forages, Landscape, Livestock, Water, and Economic Sustainability).
In Objective 1, plot-scale research under irrigated and dryland conditions will compare the performance of an Aspirational (ASP) full-year companion rotational cropping system that includes peanut, cotton, summer and winter forages, and a winter oil-rich biofuel feedstock, versus Business as usual (BAU)-1 summer peanut-cotton-corn rotation and BAU-2 summer peanut-cotton-forage rotation, both with a winter rye cover crop. Fertility management will include P-based (ASP) versus N-based (BAUs) application of Broiler litter (BL) supplemented with inorganic amendments as indicated by soil testing. All plots will be managed under strip-tillage and include field edge native wildflower habitat to enhance pollination and populations of pest arthropod natural enemies. Seasonal soil and plant sampling and analyses will be used for quantifying GxExM effects on productivity, forage and soil quality, and beneficial insect dynamics.
In objective 2, we will modify an existing three-year plot-scale experiment of continuous summer corn and winter rye conventional tillage system that examined BL and Flue gas desulfurization gypsum (FGDG) effects on P, N, carbon (C) and metals loss in runoff, and yield. The BL and FGDG annual application rates will be reduced by two-thirds for three years followed by three years with no BL and FGDG amendments. Soil cores down to 100 cm were collected at the start and are collected at three-year intervals thereafter for detailed analyses of distribution of nutrients, soil acidity, and metals. We will track nutrient dynamics in the soil, runoff, and plants from residual sources of BL and FGDG. We will also investigate factors influencing persistence of antimicrobial resistance and crop metal toxicities.
In objective 3, data acquired under objectives 1 and 2 will be used to compare farm-level economic and ecosystem services benefits and risks associated with the three cropping systems (ASP + 2BAU). Economic and environmental models will be used to synthesize the five- and ten-year outcomes of each cropping system under four weather and two land use scenarios.
All research within SEWRL is conducted as part of the ARS Long Term Agroecosystem Research (LTAR) Project. This NP 216 Project Plan is intended to augment NP 211 Conservation Effects Assessment Project (CEAP) research on crop-livestock production systems and develop an option suitable for inclusion as an LTAR ASP system.
Progress Report
Objective 1.1.: ARS scientists at Tifton, Georgia, successfully completed the second year of fall/winter 2020, and, using Mission Critical Crew only, spring 2021 field activities at 48 irrigated and 48 dryland plots at the Belflower Farm. Summer crops and forages are corn, cotton, peanuts, and tifleaf3 (millet). The fifth crop, pigeon pea, has been determined a poor fit for this system, and the research team has decided to replace it with a forage sorghum followed by sun hemp (double crop). Forages are harvested multiple times simulating foraging by cattle. For winter, ARS scientists at Tifton, Georgia, have carinata as oil crop, and a rye/ black oat mix cover as soil builder, and rye that is either hayed (simulating grazing) or chemically killed. Fertilizer rates are determined based on soil test results and the cropping system (BAU-1, BAU-2, ASP-1, and ASP-2). All plots are continuously monitored for soil water content and soil water potential with sensors that are removed before planting then re-installed after planting. Logging equipment (one for paired plots), with modem and solar charged batteries, is used to collect and transmit data to a base station.
Objective 1.2. The collaborating SY responsible for this objective retired in late December 2020. The SY sampled bees in the peanut plots but by the time the cotton was ready, the flowers had prematurely died. Furthermore, the lupine species came up nicely but then died out prior to flowering. It is not clear if heat affected the flowers or something else. The data on the many bees collected from the peanuts were sent off for identification. The plots were mowed but they will re-seed and bloom. The SY hired a technician that can maintain the flowers and mowing etc., until ARS scientists at Tifton, Georgia, can get a replacement SY on board and determine capability and interest to continue collaboration.
Objective 2.1. ARS scientists at Tifton, Georgia, continued research activities at micro-plots at Gibbs Farm under Phase III (cease poultry litter amendments; 2020, 2021, and 2022). The research assesses the impacts of application of flue gas desulfurization gypsum and poultry litter on corn production, soil properties, and nutrients in runoff. Thirty of the plots with and without grass buffers are equipped for runoff collection and sampling. In Phase III, fertilization is all inorganic (NPK) with no gypsum application except for 3 plots in each replication that during Phase II were under NPK fertilization with 2 tons per acre per year of gypsum application. The phasing allows monitoring of residual effects of poultry litter and gypsum applications as rates were reduced or eliminated. ARS scientists at Tifton, Georgia, successfully grew a winter rye cover and determined biomass. In early spring 2021, soil samples were collected and analyzed for determining fertility status and fertilizer recommendations. The rye was rolled and chemically killed before incorporating into the soil by disking and planting of the 2021 summer corn crop which is expected to be harvested in September 2021. Processing started of the 3-year interval 3-ft deep soil cores collected in spring 2020. One set of runoff samples from all 30 plots were collected in early January 2021. A manuscript by ARS scientists at Tifton, Georgia on treatment effects on water quality during Phase I (2014- Jan. 2017) was accepted late April by Journal of Soil and Water Conservation. Data on treatment effect on corn grain yield during Phase I & II have been compiled.
Objective 2.2. ARS scientists at Tifton, Georgia, completed bacteriological analysis of soil and litter samples (n =64) collected at micro-plots at Gibbs Farm under Phase II (2017, 2018) and plot runoff (n= 30) collected during a rain event in 2019. The work was possible after the project was approved as “Other Important Research” that could be conducted with a minimal crew. The research evaluates how application of soil amendments including broiler litter (BL), flue gas desulfurization gypsum (FGDG) and fertilizer (NPK) affects the persistence, distribution and transport of bacterial populations and antimicrobial resistance determinants (ARD). For microbiome analysis, collaborator sequenced the 16S rRNA gene present in amended soils, BL and FGDG and performed quantitative PCR on DNA extracted from plot runoffs to determine pathogens and ARD present. Pathogens and ARD were detected sporadically in runoff samples and the majority of the targets (16 of 25) exhibited no polymerase chain reaction signal. For instance, Salmonella was detected in three runoff samples from soils amended with either BL and FGDG or NPK, whereas Campylobacter was not detected in any sample. Similarly, the only ARD detected were for sulfonamides (sul2), streptomycin (strB) and tetracycline (tetL). These genes were found in runoff samples from soils amended with BL (n=2), BL and FGDG (n=4), NPK (n=1) and NPK and FGDG (n=5). Because the litter comes from an antibiotic-free production system, this suggests that the amendments used had little effect on ARD present in runoff. On the other hand, soils amended with BL depicted higher observed and Shannon alpha diversity indices i.e., higher evenness (species are more evenly distributed) than soils amended with NPK or NPK and FGDG. Likewise, beta diversity analysis showed a clear separation of soils amended with BL from soils amended with NPK or NPK and FGDG, suggesting that application of BL affected the bacterial community structure of the soil more than NPK and/or FGDG.
Collaborator has indicated that he will no longer be able to continue working with us vis-à-vis Objective 2.2 as his assignment has moved to a new project that does not fit any of the objectives this NP216 project. However, the collaborator is willing to complete phase II bacteriological analysis by performing microbiome analyses on soil and runoff samples collected in 2019. Future efforts on ARDs will be discontinued, and that only the MIDI community profiles will be completed for the rest of the project.
Objective 3. ARS scientists at Tifton, Georgia, continued to acquire continuous weather data from the fully operational weather station installed at Wilson Farm (Cooperator). Cooperator continues to access the data on his mobile phone and check on rainfall amount to initiate or limit irrigation. He also checks if soil temperature is adequate to initiate planting. ARS scientists at Tifton, Georgia, continued raising Mott Napier grass in green houses and replanting in marginal production areas of the farm; this grass has proven popular with cattle and producer alike and will be expanded. A cooperative agreement was signed with the cooperator that allocates a six-acre field for scaled up research on one rotation from Objective 1.1. The first cover crops of rye and carinata were planted and harvested followed by planting of cotton and peanuts on 3-ac each. These activities demonstrated that carinata could be grown and perform well in large fields but has so far proven a challenge in small fields. Under COVID-19 OIR plans, the team was able to make several trips to the farm and discuss with the cooperator location and type of flow measuring structure exiting the farm. ARS scientists at Tifton, Georgia, expect this to be operational by the end of 2021. Water sampling (grab samples) was initiated in April 2020 at the inlet and outlet of the farm.
Accomplishments
1. Grazing cover crops under wet conditions poses risk of soil compaction in the GA Piedmont. ARS scientists at Tifton, Georgia, found cool season cover crops reduce soil loss and improve soil and water quality and grazing such crops may provide incentives that increase producer adoption of the practice. ARS scientists from Beltsville, Maryland, Tifton and Watkinsville, Georgia, and Auburn, Alabama, along with a colleague from the University of Oklahoma at Stillwater, demonstrated that grazing covers during most years had no negative impact on soil compaction or rainfall runoff. However, grazing during a single wet spring in the fourth year of the study resulted in significant soil compaction down to 15 cm that was still present ten months later and was associated with higher runoff in the fall. Results suggest that producers should consider avoiding grazing during such wet springs even when fields have a long history of growing cover crops in combination with conservation tillage.
2. Satellite imagery helps to assess tall fescue health. ARS scientists at Tifton, Georgia, suggests satellite imagery supplies information on relationships between crop biomass, drought stress, and nutritional status. ARS researchers from Temple, Texas, Tifton, Georgia, and Raleigh, North Carolina, with colleagues from University of Oklahoma at Norman and Stillwater, demonstrated that choosing the “right” satellite index for assessing fescue health depends on year’s rainfall. Comparisons between the Normalized Difference Vegetation Index - NDVI, the Enhanced Vegetation Index - EVI, and the Land Surface Water Index – LSWI showed that although there was little difference the indices in normal rainfall years, EVI was more sensitive than NDVI in wet years, while NDVI was more sensitive in dry years, and LSWI was more sensitive across a greater range of values, especially those of the extreme values that farm managers are generally more interested in identifying within their paddocks. Results support the potential use of satellite imagery in assessing tall fescue health.
3. Novel endophyte-associated fescue (MaxQ) has no net negative effect on edge-of-field losses of nitrogen or phosphorus compared with wild endophyte or endophyte-free fescue. ARS scientists at Tifton, Georgia, found Tall fescue is a widely adopted cool-sea¬son perennial forage in the southeastern United States but hosts a fungal endophyte that produces an alkaloid toxic to livestock. ARS scientists near Watkinsville, Georgia, demonstrated that use of a novel endophyte-associated fescue (MaxQ – with endophyte that produces low-toxicity alkaloids) has improved stand persistence and average daily weight gain by cattle and had edge-of-field nitrogen and phosphorus losses comparable to wild endophyte or endophyte-free fescue. The study also showed that weather variability plays a significant role in nutrient losses from all three fescue systems. Across all treatments, nutrient loads were 3-to 15-fold greater from above average compared with below average monthly rainfall periods. Results suggest that MaxQ has good potential as a forage alternative in the Southeastern U.S.
Review Publications
Schomberg, H.H., Endale, D.M., Balkcom, K.S., Raper, R.L., Seman, D.H. 2021. Grazing winter rye cover crop in a cotton no-till system: Soil strength and runoff. Agronomy Journal. 113(2):1271-1286. https://doi.org/10.1002/agj2.20612.
Flynn, K.C., Lee, T., Endale, D.M., Franzluebbers, A.J., Ma, S., Zhou, Y. 2021. Assessing remote sensing vegetation index sensitivities for tall fescue (Schedonorus arundinaceus) plant health with varying endophyte and fertilizer types: A case for improving poultry manuresheds. Remote Sensing. 13(3). Article 521. https://doi.org/10.3390/rs13030521.
Endale, D.M., Schomberg, H.H., Franzluebbers, A.J., Seman, D.H., Franklin, D., Stuedemann, J.A. 2021. Runoff nutrient losses from tall fescue pastures varying in endophyte association, fertilization, and harvest management. Journal of Soil and Water Conservation. https://doi.org/10.2489/jswc.2021.00164.
