Location: Forage Seed and Cereal Research Unit
2015 Annual Report
Objectives
This research will identify crop rotation practices used in Pacific Northwest (PNW) grass seed production systems over the past decade and quantify the benefits of crop rotation diversity in promoting long stand life and high probability of successful establishment of new stands. It will also determine the value of biochar from syngas production in improving soil chemistry and quality. These data will be used to analyze farm management options that promote sustainable and profitable farming complying with environmental regulations, making wise-use of natural and crop production resources. This work will address the cumulative effects of crop management practices, field application of char, and both current and proposed conservation programs at the landscape scale, and as part of Conservation Effects Assessment Project (CEAP), determine whether the specific combinations of practices, placement, and timing will achieve desired environmental goals. These studies will be conducted in a region of highly diverse cropping systems, complex hydrology and landuse patterns, and numerous mandates to meet natural resource quality standards, including the Clean Water and Endangered Species Acts.
Objective 1. Quantify the impact of specific management practices in forage seed and cereal production systems that impact productivity and profitability.
Sub-objective 1.1. Assess the impact of diverse crop rotations on reducing input costs and breaking weed and disease cycles associated with crop diversity that increase crop and soil productivity.
Sub-objective 1.2. Quantify the impact of on-farm energy produced from crop residues and utilization of the biochar co-product as a soil amendment on energy-related input costs, soil quality, and soil carbon and nitrogen dynamics.
Objective 2. Utilize quantitative data produced in Objective 1 to develop alternative sets of management practices that optimize farm profitability and sustainability.
Sub-objective 2.1. Utilize field data to calibrate SWAT and other complex modeling tools and quantify multiple environmental effects of on-farm energy production, stand duration, tillage and nitrogen use in management of seed and cereal crops.
Sub-objective 2.2. Evaluate the effects of differing mixtures of forage seed and cereal management practices on farm-scale profitability across a diverse landscape and identify optimal sets of practices appropriate in contrasting production environments.
Approach
Meeting societal expectations for stable supplies of food and fiber while maintaining natural resource quality requires knowledge of trade-offs among multiple, often competing, objectives. Profitability along with long-term sustainability and ecosystem trade-offs are impacted by production decisions, regulations, policy, and purchasing preferences. This research project will develop information on crop management practices that promote long-duration seed crop stand life and successful establishment of new stands, the potential of char produced by gasification of crop residues as a soil amendment and value-added farm product, and will culminate in optimization analyses utilizing these data so producers and policy-makers can be given sets of management options that achieve productivity, sustainability, and profitability in different ecosystems and under alternative climate change scenarios to help bring about economic sustainability at the farm level and ecosystem services at the landscape level. The information and technologies developed within these Pacific Northwest (PNW) agroecosystems are integral parts of Conservation Effects Assessment Project (CEAP), Renewable Energy Assessment Project (REAP) and GRACEnet (Greenhouse Gas Reduction through Agricultural Carbon Enhancement network). This approach will be applied to analyze biofuel production in the Upper Mississippi River and Columbia River Basins, contrasting agroecosystems.
Progress Report
The milestones for Objectives 1, sub-objectives 1.1.1 and 1.1.2 were substantially met by showing that the vast majority of agricultural and other land-use practices in the complex landscape of western Oregon in a given year could be successfully classified using ground-truth data from years immediately preceding or following the year in question. The procedures we developed to accomplish this feat open up the possibility of a boot-strap approach to extend our knowledge of detailed land-use practices by several decades into the past. This expanded time period will allow validated modeling of water quality and other ecosystem services with the Soil and Water Assessment Tool (SWAT) over a period of growing urbanization, changing agricultural and forestry practices, and rising concerns over endangered species. Improved knowledge of past relationships between land-use practices and ecosystem services should strengthen the confidence of policymakers using tools such as SWAT to understand, predict, and mitigate the combined effects of market forces, governmental policy, and climate change on the agricultural industry and the ecosystem within which it is imbedded.
Progress with Objective 1, Sub-objective 1.2.2. reinforced our previous observations regarding the benefits that Kentucky bluegrass-sourced biochar confer to crops and soils. Progress in FY2015 included continued demonstration that Kentucky bluegrass-sourced biochar amendments increase crop yield by increasing soil pH, increasing water holding capacity, increasing water infiltration rates, and decreasing soil compaction. The results obtained from year two of this three-year on-farm field study indicated that although the effect of the biochar amendments on crop yield remained significant, the ability of the biochar to increase yield diminished over time. We were unable to determine if this observation was due to mechanical or hydraulic dilution of the biochar in field plots or if the efficacy of the biochar decreased due to weathering or to microbial degradation. ARS scientists in Corvallis, Oregon, also sampled bulk soil to quantify potential shifts in the microbiomes of biochar, lime, and non-amended soils. Our preliminary tests indicated that the bacterial and fungal populations in biochar-amended soils were significantly different than the microbial communities in the control plots. On-going experiments will focus on microbial communities in the rhizosphere to better inform the impact of biochars on the root microbiome. The established field plots were maintained and data is currently being collected to determine if the trends regarding the effect of the lime and biochar amendments are durable in third year trials. Likewise, new plots will be established in such a way to prevent mechanical dilution and mixing of biochar during normal grower-initiated maintenance of the field plots.
Kentucky-bluegrass-sourced biochar was used to amend mine tailings collected from either the Formosa or the Almeda mine to conduct proof-of-function experiments in greenhouse trials. We compared the ability of two gasified biochars from two separate source materials to increase plant germination, establishment, and growth on these very weathered and depleted soils. The results of these studies indicated that biochar amendments did confer a profound advantage in the establishment and growth of plants. Likewise, the addition of biochar prevented the accumulation of metals in plant tissues, most likely because the addition of biochar increased pH, and because the gasified biochars sorbed metals and increased soil fertility. ARS Scientists in Corvallis, Oregon also established field plots at the Formosa Mine in Riddle, Oregon. Although plants were able to establish and grow in the plots amended with Kentucky bluegrass-sourced biochar, excess run-off eroded the majority of the biochar down slope. ARS scientists are collaborating with U.S. Environmental Protection Agency (EPA) scientists in Corvallis, Oregon, to establish more substantial plots in FY15.
Progress with Objective 1, Sub-objective 1.3.1 and 1.3.2. represented significant progress towards understanding the biochemical and genetic underpinnings that lead to the production of 4-formylaminooxyvinylglycine (FVG), a compound that specifically inhibits the germination of grasses. In FY15, we made significant progress towards understanding a gene cluster that contains at least thirteen putative genes that may be involved in GAF production. Each of these genes has now been systematically deleted and reintroduced to identify those important for the regulation, transport, and biosynthesis of FVG. The most intriguing discovery is the importance of two small peptides that are encoded by small open reading frames (sORF). Although the role of these sORFs has not yet been interrogated, the discovery of their importance in FVG production represents a significant addition to the literature regarding the occurrence and relevance of sORFs in bacteria. ARS scientists in Corvallis, Oregon, in collaboration with scientists at the University of Regina, determined that FVG is also produced by Pantoea ananatis BRT175, a very ecologically and taxonomically distinct bacterium from Pseudomonas fluorescens WH6. This observation is the basis for an ongoing study exploring the geographic and ecological distribution of the FVG gene cluster in prokaryotic organisms.
Advances in identification of land-use transitions and crop rotations from Objective 1 contributed to setting up and initial calibration of a SWAT model of the Willamette Basin with rotations, substantially meeting milestone 2.1.
Economic analysis of agricultural production in large basins such as the Mississippi and Columbia is difficult because of the large number of farms and difficulty obtaining farm level data. In substantially meeting milestone 2.2, we compared profit maximization for individual farms within a small basin (Calapooia River Basin, Oregon) based on Census of Agriculture data with the results from treating the basin as if it were a single farm. The results showed that aggregating farm-level data and estimating profit gave almost the same result for the basin as maximizing profit for each farm individually. This result supports the use of aggregated economic data for analysis of a basin. Aggregated data is readily available, and has no confidentiality restrictions, unlike individual farm data.
Accomplishments
1. Cost of areal reduction of gulf hypoxia reduction through agricultural practice. A major share of the area of hypoxic growth in the Northern Gulf of Mexico has been attributed to nutrient run-off from agricultural fields, but no previous estimate is available for the cost of reducing Gulf hypoxic area using agricultural conservation practices. ARS scientists at Corvallis, Oregon, applied the Soil and Water Assessment Tool (SWAT) to simulate the reduction in nitrogen loading in the Upper Mississippi River Basin (UMRB) that would result from enrolling all row crop acreage in the Conservation Reserve Program (CRP). Nitrogen loadings at the outlet of the UMRB are used to predict Gulf hypoxic area, and net cash farm rent is used as the price for participation in the CRP. Over the course of the 42 year simulation, direct CRP costs total more than $388 billion, and the Inter-Governmental Task Force goal of hypoxic area less than 5,000 square kilometers is met in only two years. In addition, removing such a large area from grain production would result in worldwide price increases for all food commodities.
Review Publications
Trippe, K.M., Griffith, S.M., Banowetz, G.M., Whittaker, G.W. 2015. Changes in soil chemistry following wood and grass biochar amendments to an acidic agricultural production soil. Agronomy Journal. 107(4):1440-1446.
Whittaker, G.W., Barnhart, B.L., Srinivasan, R., Arnold, J.G. 2014. Cost of areal reduction of gulf hypoxia through agricultural practice. Science of the Total Environment. 505(1):149-153.
Ficklin, D.L., Barnhart, B.L., Knouft, J.H., Stewart, I.T., Maurer, E.P., Letsinger, S.L., Whittaker, G.W. 2014. Climate change and stream temperature projections in the Columbia River Basin: biological implications of spatial variation in hydrologic drivers. Hydrology and Earth System Sciences. 18:4897-4912.
Whittaker, G.W., Barnhart, B.L., Fare, R., Grosskopf, S. 2015. Application of index number theory to the construction of a water quality index: aggregated nutrient loadings related to the areal extent of hypoxia in the northern Gulf of Mexico. Ecological Indicators. 49:162-168.
Trippe, K.M., Okrent, R.A., Halgren, A.B., Azevedo, M.D., Chang, J.H., Mills, D.I., Maselko, M.B., Armstrong, D.J., Banowetz, G.M. 2014. Negative regulation of Germination-Arrest Factor (GAF) production in Pseudomonas fluorescens WH6 by a putative extracytoplasmic function sigma factor. Microbiology. 160(11):2432-2442.
Mueller Warrant, G.W., Whittaker, G.W., Banowetz, G.M., Griffith, S.M., Barnhart, B.L. 2015. Methods for improving accuracy and extending results beyond periods covered by traditional ground-truth in remote sensing classification of a complex landscape. International Journal of Applied Earth Observation and Geoinformation. 38:115-128.
Hoppe, B.O., White, D., Harding, A.K., Mueller Warrant, G.W., Hope, B.K., Main, E.C. 2014. High resolution modeling of agricultural nitrogen to identify private wells susceptible to nitrate contamination. Journal of Water and Health. 12(4):702-714.
Trippe, K.M., Griffith, S.M., Banowetz, G.M., Whittaker, G.W. 2015. Biochars derived from gasified feedstocks increase the growth and improve the nutrient acquisition of Triticum aestivum (L.) grown in agricultural alfisols. Agriculture. 5:668-681. doi: 10.3390/agriculture5030668.
Trippe, K.M., Wolpert, T.J., Hyman, M.R., Ciuffetti, L.M. 2014. RNAi silencing of a cytochrome P450 monooxygenase disrupts the ability of a filamentous fungus, Graphium sp. to grow on short-chain gaseous alkanes and ethers. Biodegradation. 25(1):137-151. doi: 10.1007/s10532-013-9646-1.
