Research Project: Contributions of Climate, Soils, Species Diversity, and Management to Sustainable Crop, Grassland, and Livestock Production Systems

Location: Grassland Soil and Water Research Laboratory

2022 Annual Report

Objectives
Objective 1: Develop procedures and quantify soil health attributes and their impact on agronomic production. Subobjective 1A: Determine the seasonal changes in inherent soil carbon and nutrient cycling potentials (N and P) using the Soil Health Nutrient Tool under conventional and no-till with two different crop rotation systems incorporating legume-dominated cover crops. Subobjective 1B: Determine the effects of conventional and conservation tillage (strip till, no-till) on soil fertility, greenhouse gas emissions, soil microbial diversity, yield, grain, fiber quality, and fertilizer use efficiency (N and P) which contribute to soil health attributes. Objective 2: Quantify native and managed grassland response to biological and climate variability. Subobjective 2A: Document long-term effects of precipitation variation on trends in biomass yield and ecosystem services from grasslands of different species composition. Subobjective 2B: Assess the linkage between the weighted values of Leaf Dry Matter Content of grassland communities and temporal variability in aboveground productivity. Subobjective 2C: Manipulate grassland community composition and resource availability to test the contributions of plant species and functional traits to grassland productivity. Objective 3: Operate and maintain the Texas Gulf Coast LTAR network site using technologies and practices agreed upon by the LTAR leadership. Contribute to the LTAR working groups and common experiments as resources allow. Submit relevant data with appropriate metadata to the LTAR Information Ecosystem. Subobjective 3A: Implement the Texas Gulf Coast LTAR Common Experiment comparing the sustainability of traditional grazing systems and adaptively managed rotational grazing systems. Subobjective 3B: Develop and enhance infrastructure for data acquisition, storage, and transfer to meet LTAR and REE data acquisition and archiving standards.

Approach
Research will apply a Genetics x Environment x Management approach quantify nutrient losses from fertilizer, interannual variability in biomass production, and grazing impacts on traditionally managed agroecosystems common in the southern U.S. Great Plains and evaluate results from management actions designed to reduce negative impacts of fertilization, precipitation variability, and grazing.

Progress Report
Sub-objective 1A. This subobjective aimed at determining seasonal changes in soil carbon and nutrient cycling potentials using the Soil Health Nutrient Tool was discontinued because of retirement of the researcher leading the work. Sub-objective 1B. We continued to evaluate the effect of tillage on greenhouse gas emissions in a corn/corn/cotton rotation under conventional till, strip till and no-till. Soil samples have been analyzed for microbial diversity and activity using Phospholipid Fatty Acid analysis for crop years 2020 and 2021 from each field. Soil, and plant tissues of corn and cotton are being analyzed for nitrogen and phosphorous uptake and use efficiency. 2022 samples have been collected and will be analyzed when the Temple, Texas, modernization is complete and allows laboratory operations to continue. Sub-objective 2A. We continued building the long-term record of year-to-year variability in biomass production from 8 native grassland and 16 switchgrass stands. The stands are approximately 1 acre in area and were harvested with commercial haying equipment and hay bales were weighed and sampled for moisture, carbon and nitrogen contents. The 2022 harvest represents the 11th year of the study, and the project is a component of our Long-Term Agroecosystem Research effort. Switchgrass stands continue to out-yield adjacent high-diversity restored grassland. Harvest subsamples from the two soil types traversed by these stands were in 2022, returning to pre-pandemic practice. We advanced the task of measuring soil carbon and nitrogen pools from soil cores collected in 2016. The new technician recruited in the previous fiscal year has completed processing and analysis of cores and segments representing the top 15 cm of the soil profile. Progress was slowed by our laboratory renovation, which limited lab space and processing and analysis capacity. We are returning to our renovated lab space now and these limitations will be mitigated. Sub-objective 2B. We advanced our ability to predict stability in biomass production in the native grassland and switchgrass stands. We conducted a fourth year of multispectral remote sensing from unmanned aerial vehicle (UAV) platforms to expand our time series of normalized difference vegetation index (NDVI) and community scale leaf dry matter content (LDMC) measurements. The lengthened time series continued to show that year-to-year change in NDVI is inversely related to year-to-year change in community scale LDMC. The robustness of this finding increases confidence in the finding that stability was regulated by year-to-year variation in community LDMC in native grassland, while in switchgrass stability depended mainly on year-to-year variation in the biomass-LDMC relationship. Sub-objective 2C. We terminated the field experiment at the end of the 2021 field season. Preliminary analysis of aboveground biomass data suggests that exotic invasive grasses such as Johnsongrass (Sorghum halepense) increase growth more than the native perennial grass switchgrass (Panicum virgatum) when growth with added water and nitrogen fertilizer, intensifying competition between the two grasses in stands grown for biomass feedstock production. Analyses of the data are on-going. Objective 3. We made numerous contributions to Long-Term Agroecosystem Research (LTAR) working groups and datasets. Scientists on this project are contributing biomass yield and site weather data to an online data repository. Scientists at Temple, Texas, have contributed to multiple LTAR publication on phenocam, manureshed, eddy covariance and phosphorus budget projects. Sub-objective 3A. We expanded our remote sensing studies of agroecosystems by beginning analysis of Sentinel-2 MSI satellite data to determine the most sensitive vegetation index for the various crop management practices. We co-led work an effort of the (LTAR) Manureshed Working Group to produce a special issue in the Journal of Environmental Quality which will be released soon. Sub-objective 3B. LTAR monitoring continued at Riesel. Soil, air, and water quality analysis were completed throughout the year, as was productivity data. ARS researchers are collaborating with USDA Natural Resources Conservation Service to develop a Conservation Plan for the Riesel Watersheds.

Accomplishments
1. Compound intensification of precipitation patterns diminish root mass and carbon fluxes. Climate change is altering precipitation regimes globally, with expectations of increased duration of dry periods interspersed with periods of heavy rainfall. The potential impacts of altered precipitation regimes remain challenging to predict. In a central U.S. grassland, ARS scientists from Temple, Texas, and university collaborators conducted an experiment that imposed an extreme 2-yr drought (66% reduction in growing season precipitation) on plots with a 16-year history of experiencing intensified precipitation and control plots experiencing the current precipitation pattern. The results revealed that an extreme multiyear drought following a long period of intensified precipitation may lead to unique but “hidden” (i.e., belowground) responses in grasslands. The history of intensified precipitation patterns amplified drought-induced reductions in root mass and length production by subdominant members of the plant community and also reduced soil carbon dioxide flux responses to precipitation events both during and after drought. These changes have potentially important consequences for ecosystem carbon cycling and storage.

2. Polyploidy confers variable climate sensitivity in the biofuel crop, Switchgrass. Polyploidy, the duplication of whole genomes in plants, is a unique form of heritable genetic variation with pronounced evolutionary and plant breeding implications. Polyploidy provides a means by which plants can adapt to new environments; however, little is known about how polyploid forms arise and how they may have adaptive advantage. Through a combination of genomic, quantitative genetic, landscape, and niche modeling approaches, ARS scientists in Temple, Texas, uncovered evidence for the genetic origins, niche differentiation, and differential environmental sensitivity of two polyploid forms (4X, 8X) of switchgrass (Panicum virgatum). These findings suggest that polyploid forms of switchgrass exist across broad portions of the species range because they represent two different adaptive strategies (8X: generalist, 4X: specialist). This unique combination of strategies in a single species has allowed the expansion of switchgrass’ ecological niche and may represent a valuable breeding resource.

3. Unmanned aerial vehicles provide a useful platform for evaluating effects of grazing on grasslands. Ecological processes on grazing lands depend on the extent to which the surface area of these ecosystems is covered by living (green) vegetation together with spatial uniformity in green coverage. However, green plant coverage is difficult to measure frequently and at the small spatial scales required to evaluate spatial patterns in living plant cover. ARS scientists in Temple, Texas, describe a technique for rapid measurements of vegetation at small spatial scale using unmanned aerial vehicles (UAVs). This technique was used to determine effects of grazing management on the extent of vegetation in pastures located in northeastern Colorado (shortgrass prairie) and central Texas (improved pasture). Variation in vegetation was well-explained by differences in sunlight reflectance from the surface of pastures at both sites. Measurements of reflectance across entire pastures using a UAV revealed that green plant coverage was similar on average among shortgrass pastures with heavy, moderate, and light grazing treatments but reduced in improved pasture by a grazing treatment in which cattle were moved monthly among pastures (rotational grazing) rather allowed to graze year-round in the same pastures (continuous grazing). Heavy grazing in the shortgrass and rotational grazing in improved pasture increased spatial uniformity in coverage of living vegetation such that adjacent areas were more similar in green plant cover under heavy grazing (shortgrass) and rotational grazing (improved pasture) than other grazing treatments. Our results indicate that UAV-enabled remote sensing provides for rapid measurement of living plant cover at sufficiently small spatial resolution to characterize spatial variation in green plant cover on grasslands. The measurements we describe provide a science-based approach to evaluate impacts of grazing treatments and other management activities on grazing lands.

4. Plant biomass production can be predicted from aggregate plant community traits. Plants that grow rapidly typically have low values of leaf dry matter content (LDMC; ratio of leaf dry mass to leaf saturated mass) and high leaf and plant nitrogen concentration ([N]). However, there is evidence that the strength of production-trait relationships and sensitivity of plant production to change in leaf traits depends on environmental conditions and the species composition of plant communities. Large environmental or compositional effects would limit the consistency of trait-based predictions of biomass production. ARS scientists in Temple, Texas, tested effects of interannual variation in precipitation and differences in plant community composition (simple monoculture vs. diverse species mixture) on relationships between aboveground biomass production of grassland and two traits, LDMC and plant [N]. Biomass production and traits were derived from remote measurements of surface reflectance of sunlight. We found that grassland production varied in space and time mainly because community LDMC varied. However, both the strength of production-trait relationships and sensitivity of plant production to trait variation depended on precipitation and plant community composition. Greater precipitation increased the production response to trait change. Precipitation effects on production-trait relationships differed between communities. We conclude that trait-based predictions of grassland biomass production can be improved by incorporating variation linked to precipitation and plant community composition.

5. Opportunities identified for improving manureshed management. The manureshed is a new concept aimed at confronting sustainability challenges facing livestock and crop production by promoting manure management practices that recycle manure resources between these systems. Because the U.S. swine industry is vertically integrated, it offers the potential to coordinate the sustainable recycling of animal manure in crop production systems. ARS scientists from Temple, Texas, along with collaborators found opportunities and challenges in achieving manureshed management within the swine industry. Manure management reflects regional differences in swine operations, resulting in a large range of land bases required to assimilate manure generated by these operations. Technology advancements are needed to promote export of concentrated nutrients, especially phosphorus, from existing “source” manuresheds to suitable croplands, which can serve as nutrient “sinks”. Industry expansion should focus on locating animals in nutrient “sink” areas.

Review Publications
Adhikari, K., Braden, I.S., Owens, P.R., Ashworth, A.J., West, C. 2021. Relating topography and soil phosphorus distribution in litter-amended pastures in Arkansas. Agrosystems, Geosciences & Environment. 4. Article e20207. https://doi.org/10.1002/agg2.20207.
Polley, H.W., Kolodziejczyk, C.A., Jones, K.A., Derner, J.D., Augustine, D.J., Smith, D.R. 2022. UAV-enabled quantification of grazing-induced changes in uniformity of green cover on semi-arid and mesic grasslands. Rangeland Ecology and Management. 80:68-77. https://doi.org/10.1016/j.rama.2021.10.001.
Menefee, D.S., Collins, H.P., Smith, D.R., Haney, R.L., Fay, P.A., Polley, H.W. 2022. Cropping management in a livestock-pasture-crop integration modifies microbial communities, activity and soil health score. Journal of Environmental Quality. 1-14. https://doi.org/10.1002/jeq2.20315.
Adhikari, K., Smith, D.R., Collins, H.P., Hajda, C.B., Acharya, B.S., Owens, P.R. 2022. Mapping within-field soil health variations using apparent electrical conductivity, topography, and machine learning. Agronomy. 12. Article 1019. https://doi.org/10.3390/agronomy12051019.
Admas, S., Tesfaye, K., Haileselassie, T., Shiferaw, E., Flynn, K.C. 2021. Genetic variability and population structure of Ethiopian chickpea (Cicer arietinum L.) germplasm. PLoS ONE. 16(11). Article e0260651. https://doi.org/10.1371/journal.pone.0260651.
Admas, S., Haileselassie, T., Tesfaye, K., Shiferaw, E., Flynn, K.C. 2021. Evaluation of chickpea (Cicer arietinum L.) genotypes for tolerance to frost in controlled environment. Sinet, Ethiopian Journal of Science. 44(2):151-160. https://doi.org/10.4314/sinet.v44i2.2.
Polley, H.W., Collins, H.P., Fay, P.A. 2022. Community leaf dry matter content predicts plant production in simple and diverse grassland. Ecosphere. 13(5). Article e4076. https://doi.org/10.1002/ecs2.4076.
Slette, I.J., Blair, J.M., Fay, P.A., Smith, M.D., Knapp, A.K. 2021. Effects of compounded precipitation pattern intensification and drought occur belowground in a mesic grassland. Ecosystems. https://doi.org/10.1007/s10021-021-00714-9. https://doi.org/10.1007/s10021-021-00714-9.
Keller, A.B., Borer, E.T., Collins, S.L., DeLancey, L.C., Fay, P.A., Hofmockel, K.S., Leakey, A.D., Mayes, M.A., Seabloom, E.W., Walter, C.A., Wang, Y., Zhao, Q., Hobbie, S.E. 2021. Soil carbon stocks in temperate grasslands differ strongly across sites but are insensitive to decade-long fertilization. Global Change Biology. 28:1659-1677. https://doi.org/10.1111/gcb.15988.
Duan, J., Yuan, M., Jian, S., Gamage, L., Parajuli, M., Dzantor, K.E., Hui, D., Fay, P.A., Li, J. 2021. Soil extracellular oxidases mediated nitrogen fertilization effects on soil organic carbon sequestration in bioenergy croplands. Global Change Biology Bioenergy. 13(8):1303-1318. https://doi.org/10.1111/gcbb.12860.
Zhou, Y., Flynn, K.C., Gowda, P.H., Wagle, P., Ma, S., Kakani, V.G., Steiner, J.L. 2021. The potential of active and passive remote sensing to detect frequent harvesting of alfalfa. International Journal of Applied Earth Observation and Geoinformation. 104. Article 102539. https://doi.org/10.1016/j.jag.2021.102539.
Polley, H.W., Kolodziejczyk, C.A., Jones, K.A., Smith, D.R. 2022. Grazing treatment influences recovery of mesic grassland from seasonal drought: An assessment using unmanned aerial vehicle-enabled remote sensing. Rangeland Ecology and Management. 82:12-19. https://doi.org/10.1016/j.rama.2022.01.008.
Dell, C.J., Baker, J.M., Spiegal, S.A., Porter, S.A., Leytem, A.B., Flynn, K.C., Rotz, C.A., Bjorneberg, D.L., Bryant, R.B., Hagevoort, R., Williamson, J., Slaughter, A.L., Kleinman, P.J. 2022. Challenges and opportunities for manureshed management across U.S. dairy systems: Case studies from four regions. Journal of Environmental Quality. 54(4):521-539. https://doi.org/10.1002/jeq2.20341.
Meinen, R.J., Spiegal, S.A., Kleinman, P.J., Flynn, K.C., Goslee, S.C., Mikesell, R.E., Church, C., Bryant, R.B., Boggess, M.V. 2022. Opportunities to implement manureshed management in the Iowa, North Carolina, and Pennsylvania swine industry. Journal of Environmental Quality. 51(4):510-520. https://doi.org/10.1002/jeq2.20340.
Bryant, R.B., Endale, D.M., Spiegal, S.A., Flynn, K.C., Meinen, R.J., Cavigelli, M.A., Kleinman, P.J. 2021. Poultry manureshed management: Opportunities and challenges for a vertically integrated industry. Journal of Environmental Quality. 1-12. https://doi.org/10.1002/jeq2.20273.
Georgiou, K., Jackson, R.B., Vindušková, O., Abramoff, R.Z., Ahlström, A., Feng, W., Harden, J., Pellegrini, A., Polley, H.W., Soong, J., Riley, W.J., Torn, M.S. 2022. Global stocks and capacity of mineral-associated soil organic carbon. Nature Communications. 13(1). Article 3797. https://doi.org/10.1038/s41467-022-31540-9.
Vázquez, E., Schleuss, P., Borer, E.T., Bugalho, M.N., Caldeira, M.C., Eisenhauer, N., Eskelinen, A., Fay, P.A., Haider, S., Jentsch, A., Kirkman, K.P., McCulley, R.L., Peri, P.L., Price, J., Richards, A.E., Risch, A.C., Roscher, C., Schütz, M., Seabloom, E.W., Standish, R.J., Stevens, C.J., Tedder, M.J., Virtanen, R., Spohn, M. 2022. Nitrogen but not phosphorus addition affects symbiotic N2 fixation by legumes in natural and semi-natural grasslands located on four continents. Plant and Soil. https://doi.org/10.1007/s11104-022-05498-y.
Napier, J.D., Grabowski, P., Lovell, J.T., Bonnette, J., Mamidi, S., Gomez-Hughes, M.J., VanWallendael, A., Weng, X., Handley, L.H., Kim, M.K., Boe, A.R., Fay, P.A., Fritschi, F.B., Jastrow, J.D., Lloyd-Reilley, J., Lowrey, D.B., Matamala, R., Mitchell, R., Rouquette, F.M., Wu, Y., Webber, J., Jones, T., Barry, K., Grimwood, J., Schmutz, J., Juenger, T.E. 2022. A generalist-specialist trade-off between switchgrass cytotypes impacts climate adaptation and geographic range. Proceedings of the National Academy of Sciences(PNAS). 119(15). Article e2118879119. https://doi.org/10.1073/pnas.2118879119.
Radujkovic, D., Verbruggen, E., Seabloom, E.W., Bahn, M., Biederman, L.A., Borer, E.T., Boughton, E., Catford, J.A., Campioli, M., Donohue, I., Ebeling, A., Eskelinen, A., Fay, P.A., Hansart, A., Knops, J.M., MacDougall, A.S., Ohlert, T., Olde Venterink, H., Raynaud, X., Risch, A.C., Roscher, C., Schütz, M., Silveira, M.L., Stevens, C.J., Van Sundert, K., Virtanen, R., Wardle, G., Wragg, P.D., Vicca, S. 2021. Soil properties as key predictors of global grassland production: Have we overlooked micronutrients? Ecology Letters. 24(12):2713-2725. https://doi.org/10.1111/ele.13894.
Carroll, O., Batzer, E., Bharath, S., Borer, E.T., Campana, S., Esch, E., Hautier, Y., Ohlert, T., Seabloom, E.W., Adler, P.B., Bakker, J.D., Biederman, L., Bugalho, M.N., Caldeira, M., Chen, Q., Davies, K., Fay, P.A., Knops, J.M., Komatsu, K., Martina, J., McCann, K.S., Moore, J.L., Morgan, J.W., Muraina, T.O., Osborne, B., Risch, A.C., Stevens, C., Wilfhart, P.A., Yahdjian, L., MacDougall, A.S. 2022. Nutrient identity modifies the destabilizing effects of eutrophication in grasslands. Ecology Letters. 25(4):754-765. https://doi.org/10.1111/ele.13946.
Witt, T.W., Flynn, K.C., Villavicencio, C., Northup, B.K. 2022. Flood tolerance and flood loss predictions for tepary bean (Phaseolus acutifolius A. Gray) across the United States Southern Great Plains. Agronomy Journal. 1-11. https://doi.org/10.1002/agj2.21084.
Spiegal, S.A., Williamson, J., Flynn, K.C., Buda, A.R., Rotz, C.A., Kleinman, P.J. 2021. Land use change and collaborative manureshed management in New Mexico. Journal of Environmental Quality. 51(4):602-613. https://doi.org/10.1002/jeq2.20280.
Zhang, L., MacQueen, A., Weng, X., Behrman, K.D., Bonnette, J., Reilley, J.L., Rouguette, F.M., Fay, P.A., Wu, Y., Fritsci, F.B., Mitchell, R., Lowry, D.B., Boe, A.R., Juenger, T.E. 2022. The genetic basis for panicle trait variation in switchgrass (Panicum virgatum). Theoretical and Applied Genetics. 135:2577-2592. https://doi.org/10.1007/s00122-022-04096-x.