Location: Southeast Watershed Research
2020 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 researchers at Tifton, Georgia, successfully completed the first year of fall/winter 2019 field activities, and, using Mission Critical Crew only, spring 2020 field activities at 48 irrigated and 48 dryland plots at the Belflower Farm. Summer crops and forages are corn, cotton, peanuts, and pigeon peas and tifleaf3 (millet). Forages are harvested by ARS researchers at Tifton, Georgia, multiple times simulating foraging by cattle. For winter, ARS researchers 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 were continuously monitored by ARS researchers at Tifton, Georgia, 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, was used by ARS researchers at Tifton, Georgia, to collect and transmit data to a base station.
Objective 1.2: In 2019, a total of 123 bees comprised of 12 species from 2 families were captured by Tifton, Georgia, in corn, peanut, and cotton representing a Shannon Diversity Index of 2.15 and applying the effective number of species [exp (2.15)], corresponds to a community with 9 equally-common species. This formula allows comparison of diversity among communities over time. A total of 47 bees were captured in corn, 5 (11%) with G. pulchella pollen, 41 (87%) with Monarda citriodora pollen, 17 (36%) with Rudbeckia hirta pollen, 13 (28%) with maize pollen and 10 (22%) with maize and one or more wildflower species pollen. A total of 47 bees were captured in peanut, 12 (26%) with G. pulchella pollen, 27 (57%) with Monarda citriodora pollen, 17 (36%) with Rudbeckia hirta pollen, 33 (70%) with peanut pollen and 26 (55%) with peanut and one or more wildflower species pollen. A total of 29 bees were captured in cotton, 4 (14%) with G. pulchella pollen, 12 (41%) with Monarda citriodora pollen, 10 (34%) with Rudbeckia hirta pollen, 8 (28%) with cotton pollen and 7 (24%) with cotton and one or more wildflower species pollen. These results suggest that the wildflowers are providing bee pollinators to the crops and the potential for crop pollination. Perennial lupine was sown late 2019 in the wildflower buffer area and will be analyzed for increases in bee abundance and diversity in the crops.
Objective 2.1. ARS reseachers at Tifton, Georgia, continued research activities at micro-plots at Gibbs Farm under Phase II (2017, 2018, and 2019) and initiated Phase III (2020-2022). ARS reseachers at Tifton, Georgia,successfully grew a winter rye cover and determined biomass. In early spring 2020, soil samples were taken and analyzed by ARS reseachers at Tifton, Georgia, 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 2020 summer corn crop which is expected to be harvested in September 2020. 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 II, poultry litter and gypsum rates were set at 2 tons per acre per year - down from 6 tons per acre per year during Phase I (2014, 2015, and 2016). 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. Surface runoff samples were obtained from two storm events with not all plots producing runoff at the same time.
Objective 2.2: Soil samples were collected by ARS reseachers at Tifton, Georgia, in April 2020 and retained in a -40C ultra low freezer to be sent to the U.S. National Poultry Research Center Athens, Georgia, when COVID-19 restrictions are lifted and laboratory analyses can proceed. DNA has been extracted from the majority of soil and broiler litter samples already received from previous years. ARS reseachers at Tifton, Georgia, tested and validated digital and qPCR primers targeting pathogens, antibiotic resistance and metal resistance genes that are associated with poultry- and the mobile genetic elements that horizontally move resistance genes across bacterial species. ARS reseachers at Tifton, Georgia, prepared 16S ribosomal RNA gene libraries for microbial community analysis. Surface runoff samples have been concentrated by filtration and filters have been stored at -80C freezer and ready for DNA extraction. Soil community structure MIDI (MIDI Labs) profiles were developed by ARS reseachers at Tifton, Georgia. Previous analysis showed that environmental DNA extracted from FGDG was too low for molecular work and consequently FGDG sampling and analysis was dropped during FY19.
Objective 3. ARS reseachers at Tifton, Georgia,continued to acquire continuous weather data from the fully operational weather station installed at Wilson Farm (Cooperator). Wilson Farm is happy with the station. Wilson Farm can access the data on mobile phones and check on rainfall amount to initiate or limit irrigation, and also check if soil temperature is adequate to initiate planting.
Mott Napier grass has been raised in green houses and replanted in selected test sites at the farm and has proven popular with cattle and producer alike. This will be expanded to much larger areas.
Initiating flow measurement at the upstream and downstream end of the stream traversing the farm has been challenging for ARS reseachers at Tifton, Georgia. One reason is that the stream has been dry for significant periods. And when it flows, the rate usually has been very low making it challenging to choose sensors that can accurately capture such low flow rates because of the shape of the stream cross section – wide and shallow. ARS reseachers at Tifton, Georgia, have considered non-contact area velocity sensors and have received quotations from vendors. However, ARS reseachers at Tifton, Georgia, might be forced to build proven measuring hydraulic structures at both ends to insure that researchers get correct flow rates. ARS reseachers at Tifton, Georgia, continue to assess this need. Dry weather also delayed anticipated start of bi-weekly stream water sample collection. Other activities are on hold because of shortage of scientist and technician positions that we have not been able to fill as well as delay in putting a cooperative agreement in place exacerbated by COVID-19.
Accomplishments
1. When it comes to predicting conservation tillage effects on erosion and nutrient loss, one size DOES NOT fit all!. Agricultural practices that reduce runoff and losses of sediment and nutrients continue to be important to ARS researchers at Tifton, Georgia. Effective application of models forecasting conservation practice effects remains elusive because soil conditions vary substantially across landscapes. ARS scientists from Tifton, Georgia, demonstrated that even for a single soil type (Cecil sandy loam) in the Georgia Piedmont, within-event rainfall pattern can have as much effect on soil erosion and nutrient transport as tillage management. Rainfall simulations were conducted on tilled versus no-tilled sites during the fourth and fifth year of a continuous corn study. The same depth of rainfall was applied at either a constant rate of 57 mm/hr versus a variable rate that simulated typical within-event variability common to the location (peak rate up to 150 mm/hr). Using the constant rate simulation that is the standard for estimating erosion potential, runoff and sediment loss rates were 5.5- and 11-fold greater for tilled versus no-till soil management. However, simulations mimicking typical within-event rainfall intensity variations resulted in substantially higher runoff from no-till soil management systems such that, although runoff from the tilled system was 1.3-fold higher than from the no-till system, the difference was not significant. Similarly, although sediment loss increased from both tillage systems, the increase was much larger from no-till, so that net loss from conventional tillage (CT) was only 2.2-fold higher than from no-till (NT). Nitrate and ammonium losses were higher from no-till than conventional tillage under both simulations, but dissolved reactive and total phosphorus losses were higher only under the variable rate simulation. Results highlight the need to account for the variable nature of natural rainfall among seasons when constructing water quality model input conditions for conservation practice planning and impact assessments.
2. Effect of poultry litter on soil pH is dependent on soil type and cropping system. Soil acidity is a constraint to global food security and access to limestone to correct this problem is limited in many parts of the world. Research suggests that animal manures have a liming effect on acidified soils but the effect may be moderated by tillage management. However, researchers from ARS Tifton, Georgia, and Texas A&M Univeristy found that cropping system (6 years in cotton with winter wheat cover crop; 5 years in corn with winter rye; and 4 years in millet with winter rye) affected soil pH and lime buffer capacity more than tillage (conventional versus no-till) or fertilizer treatment (inorganic versus poultry litter) in a Georgia piedmont Cecil sandy loam. Although conventional tillage with poultry litter treatment resulted in a 0.6-unit pH increase in the top 15 cm of soil, lime buffer capacity remained unchanged at all but at the 75-90 cm depth where all treatments exhibited a decrease over time. Results suggest that previously reported liming effect of animal manures should be examined in the context of soil type and cropping system to better understand the true mechanism(s) of soil acidity amelioration.
3. Promoting “Manuresheds” for sustainable intensification of US agriculture. Animal manure is a valuable byproduct of the livestock industry and application to cropland and hayland is a common practice for both enhancing soil fertility and environmentally friendly waste disposal. However, managing manures is one of the most difficult challenges of modern agriculture, affecting not only resource management, but also crop production and human and environmental health. ARS scientists at Tifton, Georgia, collaborated across ten sites of the USDA’s Long Term Agroecosystem Research (LTAR) network, classified the 3109 counties of the contiguous U.S. in terms of their capacity to supply manure phosphorus from livestock production (“sources”) or assimilate and remove excess phosphorus via application to croplands and hay lands (“sinks”). Results showed that there is potential to redistribute manure from source to sink counties across much of the country while meeting regional production, economic, and environmental goals. The resulting four “Manuresheds” represent various regional combinations of beef, dairy, poultry, and swine industries and thus differ in the transport distances needed to assimilate excess manure phosphorus (from 147 ± 51 km for a beef and dairy dominated manureshed to 368 ± 140 km for a poultry dominated manureshed). The analysis and outcomes highlight the need for collaborative strategies that promote manure nutrient recycling across local, county, regional, and national scales to meet multiple goals.
Review Publications
Endale, D.M., Schomberg, H.H., Truman, C., Franklin, D., Tazisong, I., Jenkins, M., Fisher, D. 2019. Runoff and nutrient losses from conventional and conservation tillage systems during fixed and variable rate rainfall. Journal of Soil and Water Conservation Society. 74(6):594-612. doi:10.2489/jswc.74.6.594.
Mower, J., Endale, D.M., Schomberg, H.H., Norris, S.E., Woodroof, R.H. 2019. Liming potential of poultry litter in a long-term tillage comparison. Soil & Tillage Research. https://doi.org/10.1016/j.still.2019.104446.
Spiegal, S.A., Kleinman, P.J., Endale, D.M., Bryant, R.B., Dell, C.J., Goslee, S.C., Meinen, R.J., Flynn, K.C., Baker, J.M., Browning, D.M., McCarty, G.W., Bittman, S., Carter, J.D., Cavigelli, M.A., Duncan, E.W., Gowda, P.H., Li, X., Ponce, G., Raj, C., Silveira, M., Smith, D.R., Arthur, D.K., Yang, Q. 2020. Manuresheds: Advancing nutrient recycling in US agriculture. Agricultural Systems. 182:102813. https://doi.org/10.1016/j.agsy.2020.102813.
