Research Project: Enhancing Production and Ecosystem Services of Horticultural and Agricultural Systems in the Southeastern United States

Location: Soil Dynamics Research

2021 Annual Report

Objectives
1. Assess above- and belowground responses of pastures to elevated CO2 and their ability to help mitigate climate change via sequestration of CO2. 1a. Process and publish on biomass (above- and belowground) and soil physicochemical data, inclusive of soil C and N dynamics, from the 10-year CO2/N bahaigrass pasture study. 1b. Plant a Southeastern bermudagrass pasture to determine the effects of atmospheric CO2 level and N management on above- and belowground responses of the plant/soil system. 1c. Process and publish on soil flux of trace gases (CO2, N2O, CH4) from the 10-year CO2/N bahaigrass pasture study. 1d. Plant a Southeastern bermudagrass pasture to determine the effects of atmospheric CO2 level and N management on soil flux of trace gases (CO2, N2O, CH4). 1e. Determine the effects of elevated CO2 on efficacy of herbicidal control of weeds problematic in Southeastern agricultural systems. 1f. Work on effects of elevated CO2 on growth and efficacy of herbicidal control of herbicide resistant weed populations. 2. Manipulate fertilizers, soil amendments such as biochar, and irrigation in ornamental horticultural systems to reduce GHG emission and increase C sequestration. 2a. Identify best management practices (e.g., fertilizer placement, irrigation method) that reduce GHG emissions while optimizing growth for various horticulture crops. 2b. Determine the longevity of carbon in horticultural growth media (e.g., pine bark, clean chip residual, whole tree) following placement in the landscape. 2c. Investigate the effects of biochar in growth media (pine bark) on growth, nutrient retention, and GHG emissions in various ornamental horticultural crops. 3. Develop improved methods to utilize organic waste and soil amendments for soil and crop benefits while minimizing environmental degradation. 3a. Determine the rate of Flue Gas Desulfurization (FGD) gypsum needed to increase corn yield and reduce soluble P concentration in soil. 3b. Determine the rate of FGD gypsum needed to reduce P losses in runoff under no-till and conventional tillage. 3c. Determine the influence of poultry litter as a nutrient source for winter wheat and canola, and its residual effects on succeeding soybean and wheat crops. 3d. Evaluate the influence of poultry litter vs. inorganic fertilizer on crop production under different management practices. 3e. Develop a four-band implement for subsurface band application of pelletized poultry litter, poultry litter, and similar solid manures. The implement will use pneumatic conveying or a similar method to convey the product. 3f. Evaluate effectiveness of subsurface application of poultry litter for row crop production. 3g. Develop novel and economically viable uses for poultry litter, including innovative soil and manure analysis systems for precision manure management. 4. Develop management practices for economically and environmentally sustainable full life-cycle poultry production systems.

Approach
A long-term Southeastern bahaigrass pasture study will be terminated and a bermudagrass pasture study will be initiated. Both systems are exposed to current and projected levels of atmospheric CO2 and either managed (N added) or unmanaged (no N). Carbon flux to plants (biomass growth, allocation, and quality) and soil will be determined with supporting data on soil physicochemical properties. Emphasis will be given to measuring soil C and N dynamics and C storage, root growth, water quality, and GHG (CO2, N2O, and CH4) flux from soil. Using the same CO2 levels, container studies on weeds important to the southeastern U.S. (including those resistant to herbicides) will evaluate herbicide efficacy, regrowth, biomass, and tissue quality. In addition, research will evaluate production practices (in terms of such factors as fertilizer placement, growth media, and irrigation) to identify best management practices which ensure productivity, minimize GHG emissions, and maximize belowground C storage. Other work will examine how the application of organic waste to soil can improve soil conditions via C addition and provide nutrients needed for crop production. Poultry litter may be a viable fertilizer option for crop producers in the Southeastern U.S. given the large amounts of manure generated by the poultry industry. However, improper application of animal waste can contribute to environmental degradation such as increased hypoxia, eutrophication, human health problems, and greenhouse gas emissions. Due to these environmental and animal health concerns, studies will be established to develop improved methods to utilize waste products for animal and crop benefits. Research and development of technologies to recover phosphorous from manure, transform manure into secondary byproducts and find alternative, environmentally safe and economical usages of manure will be undertaken. Studies will be initiated to determine long term effects of poultry litter on plant yields, and soil physicochemical properties (including C storage) under various cropping systems. Further, different poultry litter application practices, such as subsurface banding, will be evaluated to determine their impact on nutrient loss and greenhouse gas emissions. Soil amendments (e.g., gypsum) will be evaluated both as a poultry house bedding material and as a soil amendment to determine the impact on animal production, plant responses, and the potential to reduce NH4 emissions and phosphorus (P) loss in runoff. Information acquired in the course of this project will be useful for developing improved poultry and crop production practices. Integrating data from these studies will be economically analyzed to aid understanding on how to adjust future poultry production and agronomic management practices to sustain productivity, while aiding mitigation of global change via increasing soil C sequestration and reducing greenhouse gas emissions.

Progress Report
Final report, project will be replaced by a bridging project pending completion of research review. World food stability depends on productive agricultural systems, but environmental concerns must be addressed for these systems to be sustainable. Increasing atmospheric CO2 and other greenhouse gases (GHG) are factors driving climate change. Understanding how environmental change impacts agriculture and how management affects soil C storage and GHG emissions are crucial for developing mitigation strategies. Research examined impacts of elevated CO2 on pasture and other cropping systems. Efforts included assessing horticultural management effects on GHG emissions. New methodology based on Inelastic Neutron Scattering (INS) was developed to rapidly quantify soil C in situ. Methods utilizing waste products (e.g., poultry litter, gypsum) that minimize environmental degradation while providing for nutrient, soil, and economic crop benefits were assessed in developing management strategies. Research addressed priority issues providing a scientific foundation for decision-making/policy development and knowledge to enhance predictive capabilities aiding growers to adapt sustainable management practices to a changing environment. A 10-year bahiagrass pasture study managed with or without N fertilization was conducted to assess forage production under ambient or elevated CO2. Added N significantly increased biomass regardless of CO2 level. High CO2 increased biomass only with added N highlighting the importance of future soil N management. Added N increased intra-aggregate porosity and pore space in large aggregates yielding an increase in water retention; these effects were enhanced by elevated CO2 and may have global implications (e.g., water balance, C storage, belowground functions) of importance to climate modelers since droughts are predicted to increase. Other work found that a low water use efficiency (WUE) soybean cultivar had higher photosynthesis under high CO2, but did not increase yield. A high WUE cultivar had lower seed mineral concentrations but higher total nutrients due to increased seed yield under high CO2. Findings showed that genetic variation needs to be considered in breeding programs. Work with an industrial sweet potato found that elevated CO2 increased tuber dry weight (41%) enhancing the capabilities of bioethanol producers. Management effects on GHG emissions in ornamental horticulture found that dibbling fertilizer (vs. incorporated or top-dressed) decreased CO2 and N2O losses. Research found that drip irrigation decreased N2O emissions regardless of fertilizer placement; if limited to overhead irrigation, dibbling fertilizer decreased N2O loss. Evaluations of growth substrates [80:20 peat:perlite, 80:20 peat:WholeTree (whole pine tree-based substrate), 60:40 peat:WholeTree] on GHG emissions found that containers with 40% WholeTree had higher CO2 loss with no differences in N2O or CH4. Using a high wood fiber substrate in similar proportions to that of perlite in an industry standard mix (20%) yielded similar plants with no negative impact on GHG loss. Research led to the development of a patented method for specific microbial inoculants to reduce N2O emissions from N fertilization. New tool could aid producers in generating an income stream in the C trading market to reduce GHG impacts. Allied work assessed U.S. NH3 emissions and global N2O emissions in croplands. Modeling efforts identified the Mid-South as one region displaying increases in NH3 emissions and that global cropland N2O emissions increased by 180% (1961-2014) with synthetic N fertilizer responsible for ~70% of total emissions (2000-2014). East Asia took the lead in N2O emissions after the 1990s from Europe and North America. New information will help policy makers in developing mitigation strategies for agricultural NH3 and N2O emissions under future climate change scenarios. Additional efforts refined an in situ, rapid, non-destructive technique of measuring soil C (and other elements) using the INS method. Research resulted in two patents and two pending patents. Findings indicated that INS can rapidly quantify and map C in agricultural soils that will identify best management practices for maintaining soil productivity and mitigating climate change. Method can also be used to rapidly assess C to N ratios of bulk compost materials (e.g., animal wastes). INS technology can greatly facilitate the timely construction of soil C maps and soil C storage measurements; licensed to company for worldwide use as a sound quantification tool for the C trading market. A CRADA agreement is in place with this company to further develop the commercial uses of the methodology. P loss from agricultural fields (especially those receiving manure) is a major cause of surface water eutrophication. One approach to reduce P runoff is to treat manure or soil receiving manure with chemical amendments such as gypsum. Showed that gypsum use with poultry litter (PL) was effective in reducing P loss which led to the USDA–NRCS creating a National Conservation Practice Standard (333, Amending soil properties with gypsum products) for the use of gypsum in agriculture. Other work regarding loss of soil macro- and micronutrients with gypsum use and research examining potential toxicity from excessive ingestion of gypsum by ruminants showed that, while these problems can exist under mismanagement, no concerns exist when gypsum is applied as outlined in the USDA-NRCS Standard 333. Further work showed that there was no heavy metal contamination from agriculture application of flue gas desulfurization (FGD) gypsum and these findings are being used by the U.S. EPA to conduct a risk assessment of using this industrial waste in agriculture. Current recommended practice for reducing P loss from fields receiving manure or PL is to apply gypsum on top of the manure source in a second operation, which increases producer costs. A more effective approach would be to mix gypsum directly with the manure source, but this adds a processing cost. If gypsum was used as the poultry bedding material, then the manure/gypsum mixture would be the PL when it is cleaned out of poultry houses. Findings showed that gypsum resulted in small decreases in bird body weight and adjusted feed efficiency, but lowered mortality, footpad lesions, and NH3 volatilization thereby increasing production efficiency. In addition, a new method was developed to quantify NH3 loss to evaluate efficacy of agricultural fertilizer application practices. Further, a first examination of the effects of different litter materials on gas emissions from broiler house bedding showed that FGD gypsum reduced NH3 but had little impact on other GHG emissions. Overall, gypsum is a promising alternative bedding material for poultry broiler production. Additional work showed that adding gypsum to horticulture potting media reduced P loss and indicated that this addition could greatly reduce the horticulture industry’s contribution to nutrient loading of surface waters. PL has historically been used as a fertilizer in cropping systems and we determined how PL nutrient composition is influenced by poultry house management (i.e., clean-out frequency, removal depth, bird size, number of flocks raised on bedding). Composted PL had slightly higher N, P and Ca and lower C than PL taken directly from houses. Nutrients tended to be higher in caked PL than PL from the entire six-inch depth and increased with flocks and decreased with frequency of clean-out. Overall, PL had a fertilizer grade of 3-3-2 for N-P-K. Since PL has typically been surface applied where it is susceptible to runoff loss in cropping systems, we examined subsurface PL banding to minimize P runoff losses. Placing bands 5 cm adjacent to corn rows resulted in germination rates and early growth similar to surface application; however, seeding directly into PL bands reduced emergence and inhibited growth. Further work in a double-cropping system showed that a combination of PL and inorganic N resulted in wheat yields comparable to those with inorganic N alone, while PL alone had lower yield. Double-cropping soybeans with winter wheat tended to improve soybean yield; however, soybean yield was not consistently enhanced by residual PL nutrients (from the wheat crop). Similarly, work with winter canola showed that PL with commercial fertilizer resulted in equivalent growth compared to commercial fertilizer, while PL alone was less effective. In addition, a comprehensive meta-analysis review of PL use in crop production indicated that PL was comparable to inorganic N with the greatest benefits occurring with long-term annual (3 or more) PL applications. This work also included engineering development of prototype field implements for shallow subsurface band application, inclusive of testing blower and conveyer belt delivery systems. Additional work found that cotton seedling emergence was not impacted by planter closing wheel type. Due to the importance of soil compaction limiting root growth, engineering efforts also included the development of a soil shear strain model that could be useful for the design and analysis of agricultural implements. Working with the U.S. Army Corps of Engineers, developed technology using pulverized wastepaper to rehabilitate degraded U.S. Army training lands and a means of using a waste stream generated from classified paper without landfilling. Paper waste had no adverse environmental effects and helped establish desirable native vegetation. The White House’s Climate 21 Project highlighted this project as how the Federal Government can respond to climate change. Other work utilizing paper industry waste byproducts in agroforestry systems of southern Brazil generated findings important to growers for identifying good fertility management practices which can be applicable to the southeastern U.S. given the similar climates.

Accomplishments
1. Growth substrate effects on greenhouse gas emissions in horticulture were studied. Much of the work on reducing greenhouse gas (GHG) emissions and increasing carbon (C) sequestration has been conducted in row crop and forest systems; however, virtually no work has focused on contributions from sectors of the specialty crop industry such as ornamental horticulture. Ornamental horticulture impacts rural, suburban, and urban landscapes. Since little is known about the impact of the horticulture industry on these driving factors, ARS researchers in Auburn, Alabama, have an on-going joint effort with the Horticulture Department at Auburn University to determine baseline GHG emissions, develop strategies to reduce these emissions, and develop strategies to increase soil C storage. A study on GHG emissions from three annual species (coleus, vinca, and impatiens) grown in three substrates [80:20 peat:perlite, 80:20 peat:WholeTree (a whole pine tree-based substrate), 60:40 peat:WholeTree] was conducted. Coleus had the highest cumulative CO2 efflux due to its increased size. Containers with the highest proportion of WholeTree (40%) tended to have more cumulative CO2 efflux. There were no differences in N2O or CH4 efflux. Results suggest that using a more sustainable high wood fiber substrate in similar proportions to that of perlite in an industry standard mix (20%) could yield similarly sized plants with no negative impact on GHG emissions. This work continues to identify best management practices that can reduce GHG emissions from container produced ornamental crops.

2. Response of soybean genotypes to elevated CO2. The rise in atmospheric CO2 will likely increase photosynthesis and seed yield in soybean. Breeding for high water use efficiency (WUE) could change carbon uptake by leaves and seed nutrient levels under increasing atmospheric CO2 due to lower stomatal conductance. ARS researchers in Auburn, Alabama, examined two cultivars with differing WUE under ambient and elevated CO2 conditions. The low WUE cultivar had higher photosynthesis under high CO2 due to higher stomatal conductance, while the high WUE cultivar compensated by producing more leaf area. However, this improved photosynthesis did not translate into more biomass or seed yield under high CO2 compared to the high WUE cultivar that had better assimilate partitioning. The high WUE cultivar generally had lower seed mineral concentrations but higher total nutrient amounts due to increased seed yield under high CO2 compared to the low WUE cultivar. Findings showed important genetic variation in soybean response to elevated atmospheric CO2 that needs to be considered in breeding for future atmospheric CO2 scenarios.

3. Modeling of ammonia emissions across the U.S. Over the last century, the global N cycle has been heavily perturbed by additions of reactive N from human activities leading to increased atmospheric ammonia (NH3). Synthetic N fertilizer application and livestock manure management are two dominant atmospheric NH3 sources that account for ~80% of total NH3 emission in the U.S. ARS researchers in Auburn, Alabama, applied this salellite based modeling effort on 14-year monthly NH3 dataset to explore change in NH3 patterns and relationships with N fertilizer application, livestock manure production, and climate factors across the US. In addition to the U.S. Midwest, the Mid-South and Western regions also experienced a striking increase in NH3 concentrations. Monthly atmospheric NH3 concentrations were positively correlated with monthly surface temperature in five U.S. regions, with the highest found in the Mid-South. The influence of temperature on NH3 concentrations was related to N fertilizer use in the Northern Great Plains and NH3 released from livestock manure during warmer winters contributed to increased NH3 in the Western U.S. This new information will help policy-makers in developing mitigation strategies for agricultural NH3 emissions under future climate change scenarios.

4. Modeling of global nitrous oxide emissions in croplands. ARS researchers in Auburn, Alabama, have made substantial efforts to quantify global and regional N2O emissions from cropland soils in the last three decades using a wide variety of approaches and estimates remain largely uncertain. Moreover, how annual and decadal climate changes and variability affect N2O emissions from cropland is unknown. A Dynamic Land Ecosystem Model (DLEM) was used to characterize global nitrous oxide (N2O) emissions from cropland driven by multiple environmental factors and management strategies. Estimates suggest that global cropland N2O emissions increased by 180% during 1961-2014 (1.1 to 3.3 Tg N yr-1). Synthetic N fertilizer was responsible for ~70% of total emissions during 2000-2014. At regional scales, Europe and North America were leading regions for N2O emissions in the 1960s, but East Asia took the lead after the 1990s. This study considered various N input sources and environmental factors to provide time series estimates of N2O emissions. Such information could help develop future N2O mitigation strategies by countries with higher emission rates.

5. Gypsum additions to horticulture potting media reduces phosphorus losses to the environment. In response to agriculture’s contribution to surface water quality, ARS researcher in Auburn, Alabama, have made considerable to develop best management practices to reduce nutrient loss. To evaluate the efficacy of gypsum as a horticultural media amendment for controlling dissolved reactive phosphorus (DRP) leaching, flue gas desulfurization (FGD) gypsum was added at different rates to a standard horticultural growth medium by either mixing or placing at the bottom of the containers. Gypsum additions greatly reduced P leaching, with the greatest P leaching occurring with the fertilizer-only treatments (no gypsum). Increasing rates of FGD gypsum addition resulted in decreasing DRP leaching concentration losses and loading. The FGD gypsum decreased leachate DRP concentration loss by a maximum of 75%, with an average decrease of 46%. FGD gypsum remained effective in reducing DRP loss throughout the experiment. Mixing the FGD gypsum with the medium (an easier/less expensive means of using the gypsum in the pots) was most effective with the fast-release fertilizer. These results indicate that less gypsum may be needed to reduce P loss from fast-released fertilizer as opposed to control-release fertilizer. These results indicate that the addition of FGD gypsum to standard potting media could greatly reduce the horticulture industries’s contribution to nutrient loading to surface waters.

Review Publications
Frigo, C., Magri, E., Barbosa, J., Sarteretto, L., Araujo, E., de Melo, V., Prior, S.A., Motta, A. 2020. Influence of roadways on heavy metal content in soils and yerba mate tissue in southern Brazil. Management of Environmental Quality. 31(6):1477-1495. https://doi.org/10.1108/MEQ-10-2019-0219.
Robbins, D.H., Johnson, C.E., Schafer, R.L., Way, T.R. 2021. Modeling soil-metal sliding resistance. Transactions of the ASABE. 64(2):435-446. https://doi.org/10.13031/trans.13978.
Chakraborty, D., Prasad, R., Bhatta, A., Torbert Iii, H.A. 2021. Understanding the environmental impacts of phosphorus in acidic soils receiving repeated poultry litter applications. Science of the Total Environment. 779(2021):146267. https://doi.org/10.1016/j.scitotenv.2021.146267.
Xu, R., Tian, H., Pan, S., Prior, S.A., Feng, Y., Dangal, S. 2020. Global N2O emissions from cropland driven by environmental factors and nitrogen addition: comparison and uncertainty analysis. Global Biogeochemical Cycles. 34:e2020GB006698. https://doi.org/10.1029/2020GB006698.
Adam, W.M., Dos Santos Rodrigues, V., Magri, E., Motta, A., Prior, S.A., Zambon, L.M., Lima, R.D. 2021. Mid-rotation fertilization and liming of Pinus taeda L.: litter, fine root mass, and elemental composition. iForest. 14(2):195-202. https://doi.org/10.3832/ifor3626-014.
Consalter, R., Barbosa, J., Prior, S.A., Vezzani, F., Bassaco, M., Pedreira, G., Motta, A. 2020. Mid-rotation fertilization and liming effects on nutrient dynamics of Pinus taeda L. in subtropical Brazil. European Journal of Forest Research. 140:19-35. https://doi.org/10.1007/s10342-020-01305-4.
Magri, E., Gugelmin, E., Grabarski, F., Barbosa, J., Auler, A., Wendling, I., Prior, S.A., Valduga, A., Motta, A. 2020. Manganese hyperaccumulation capacity of Ilex paraguariensis A. St. Hil. and occurrence of interveinal chlorosis induced by transient toxicity. Ecotoxicology and Environmental Safety. 203:111010. http://doi.org/10.1016/j.ecoenv.2020.111010.
Sass, A., Bassico, M.V., Motta, A.C., Maeda, S., Barbosa, J.Z., Bognola, I.A., Bosco, J.V., Goularte, G.D., Prior, S.A. 2020. Cellulosic industrial waste to enhance Pinus taeda nutrition and growth: a study in subtropical Brazil. Scientia Forestalis. 48(126):e3165. https://doi.org/10.18671/scifor.v48n126.13.
Soba, D., Shu, T., Runion, G.B., Prior, S.A., Fritschi, F., Aranjuelo, I., Sanz-Saez, A. 2020. Effects of elevated [CO2] on photosynthesis and seed yield parameters in two soybean genotypes with contrasting water use efficiency. Environmental and Experimental Botany. 178:104154. https://doi.org/10.1016/j.envexpbot.2020.104154.
Consalter, R., Motta, A.C., Barbosa, J.Z., Vezzani, F.M., Rubilar, R.A., Prior, S.A., Nisgoski, S., Bassaco, M.V. 2021. Fertilization of P. taeda L. on an acidic oxisol in southern Brazil: growth, litter accumulation, and root exploration. European Journal of Forest Research. 140:1095-1112. https://doi.org/10.1007/s10342-021-01390-z.
He, Y., Xu, R., Prior, S.A., Yang, D., Yang, A., Chen, J. 2021. Satellite-detected ammonia changes in the United States: natural or anthropogenic impacts. Science of the Total Environment. 789:147899. https://doi.org/10.1016/j.scitotenv.2021.147899.
Murphy, A., Runion, G.B., Prior, S.A., Torbert III, H.A., Sibley, J.L., Fain, G.B., Pickens, J. 2021. Effects of growth substrate on greenhouse gas emissions from three annual species. Journal of Environmental Horticulture. 39(2):53-61. https://doi.org/10.24266/0738-2898-39.2.53.
Ulbrich, N.C., Prado, L.L., Barbosa, J.Z., Araujo, E.M., Poggere, G.C., Motta, A.C., Prior, S.A., Magri, E., Young, S.D., Broadley, M.R. 2022. Multi-elemental analysis and health risk assessment of commercial yerba mate from Brazil. Biological Trace Element Research. 200:1455-1463. https://doi.org/10.1007/s12011-021-02736-9.
Prior, E.M., O'Donnell, F., Brodbeck, C., Runion, G.B., Shepherd, S.L. 2020. Investigating UAS multispectral imagery for total suspended solids and turbidity monitoring in small streams. International Journal of Remote Sensing. 42(1):39-64. https://doi.org/10.1080/01431161.2020.1798546.
Prior, E.M., O'Donnell, F.C., Brodbeck, C., Donald, W.N., Runion, G.B., Shepherd, S.L. 2020. Measuring high levels of total suspended solids and turbidity using small unoccupied aerial systems (sUAS) multispectral imagery. Drones. 4(3):54. https://doi.org/10.3390/drones4030054.
Bhatta, A., Chakraborty, D., Prasad, R., Shaw, J., Lamba, J., Brantley, E., Torbert Iii, H.A. 2021. Suitability of mehlich 3 as a universal soil test extractant for phosphorous loss risk assessment for diverse soil regions. Agrosystems, Geosciences & Environment. 4(3):e20187. https://doi.org/10.1002/agg2.20187.