Location: Agroecosystems Management Research2018 Annual Report
Objective 1: Improve nutrient and water-use efficiency and decrease environmental impacts of corn-soybean systems in the Midwest. Sub-objectives: 1.1 Determine effects of cover crops, bio-char applications, and biomass removal for bio-energy feedstock production on soil nutrient dynamics and crop yield; 1.2 Determine winter cover crop and tillage effects on water quality and N balance in a corn-soybean rotation; 1.3 Determine winter cover crop effects on soil quality and plant health in a corn-soybean rotation; 1.4 Develop and populate a SQL structured database to link with crop simulation models to evaluate cropping system responses to changing climate and management practices. Objective 2: Evaluate nutrient cycling and environmental impacts of alternative cropping systems. Sub-objectives: 2.1 Determine effects of organic cropping systems on water quality and soil profile water storage; 2.2 Determine effects of organic cropping systems on soil C and N storage and soil quality; and 2.3 Develop and populate a SQL structured database to link with crop simulation models to evaluate alternative cropping system responses to changing climate and management practices. Objective 3: Intercompare crop and economic models and foster improvements in these models to increase their capability to utilize data from climate scenarios as part of AgMIP.
A combination of controlled experiments in the field and laboratory, tile drainage monitoring, and a variety of modeling techniques and statistical analyses will quantify the effects of corn stover removal on nutrient cycling and the ability of winter cover crops to reduce nitrate losses and improve soil quality in a conventional corn-soybean production system. In an organic production system with extended rotations and manure application, we will examine system effects on nitrate losses and soil quality. To assess cultural practices that can improve nutrient- and water-use efficiency and decrease environmental impacts of corn-soybean systems in the Midwest, we will determine effects of cover crops, bio-char application, and biomass removal for bio-energy feedstock production on soil nitrogen (N), phosphorus (P), potassium (K), and sulfur (S) dynamics and corn yield, determine winter cover crop effects on N balance and water quality, determine cover crop effects on soil quality and plant health, and develop and populate a Structured Query Language (SQL) database to link with crop simulation models to evaluate cropping system responses to changing climate and management practices. To evaluate nutrient cycling and environmental impacts of alternative cropping systems, we will determine effects of organic cropping systems on water quality, soil profile water storage, soil carbon (C) and N storage, and soil quality. With the data, we will develop and populate a database to link with crop simulation models in order to evaluate alternative cropping system responses to changing climate and management practices.
This is the final report for project 5030-21610-002-00D, terminating August 4, 2018. During the five years of the project, significant progress was made in developing cropping systems for enhanced sustainability and environmental quality in the upper Midwest. Research addressed corn grown for grain and as a feedstock for the emerging bio-energy and bio-based products industries under a variety of management systems, including continuous corn, corn rotated with soybean, corn rotated with alfalfa, and a corn/cereal rye-soybean/winter wheat-tillage radish rotation, all under standard fertility management (Objective 1). We found that after the fifth growing season, nitrogen was the most limiting nutrient for the growing crops. Although nitrogen fertilizer was applied at planting and again when the plants were at the V6 (six-leaf) growth stage, these results suggest that nitrogen fertilizer application rates, placement, and timing could be further adjusted to better meet the needs of the four management scenarios. Corn stover (plant residue) harvest did not decrease corn grain and soybean yields, and offers a residue management option for no-till production in central Iowa. To the contrary, corn grain yield was increased 10% when stover was harvested. Corn grain yields were similar between chisel plow and no-till when some amount of stover was removed. Delaying soybean planting to harvest rye vegetation produced 4.0 Mg ha-1 of rye and 2.9 Mg ha-1 of soybean. Including a cereal rye cover crop in a continuous corn production system did not reduce average grain yield, with or without corn stover harvest. Soil analyses indicated no consistent changes after five years of stover harvest. Application of biochar did not affect corn grain or stover yields in this study. At a tile drainage water monitoring site (Objective 1), new experimental treatments were established that include no-till with cereal rye cover crops, no-till with no cover crops, and a fall-tilled treatment with spring-applied anhydrous ammonia. Cereal rye cover crops were successfully established last fall and biomass samples taken both last fall and this spring. Tile drainage samples were collected when there was flow and analyzed for nitrate, ammonia, phosphorus, and potassium. Soybean was grown in 2017, with no nitrogen applied at or after planting. Corn was successfully planted this year, and nitrogen (N) fertilizer in the no-till plots was applied after planting at rates based on the late spring soil nitrate test. Data from the previous experiment is being analyzed and a publication is being developed. Research examined corn seedling root diseases following cereal rye cover crops (Objective 1); data were analyzed from controlled environment experiments, a research paper was submitted, and several other research reports and papers are being prepared. Experiments examined the effects of fungicide-treated and untreated corn seed on corn seedling diseases following cereal rye and other cover crop species. Fungicides generally reduced Pythium disease, but were not effective against Fusarium. At one field site, cereal rye, camelina, and hairy vetch were evaluated to determine their effect on both corn and soybean seedling disease. At a second field site, early banded and broadcast herbicide treatments to terminate rye and different starter fertilizer treatments for corn following a cereal rye cover crop were examined for their effect on corn seedling diseases and subsequent corn growth. The second year was completed last fall and a third year is in progress. Cover crop biomass, corn emergence, corn population, seedling root disease incidence, and plant height were measured. A field experiment comparing organic and conventional crop rotations and their effects on agronomic, soil, and environmental parameters (Objective 2) was continued into a sixth year. In addition to crop growth and yield, tile drainage water flow, drainage water nitrate, dissolved organic carbon and nitrogen concentrations, and soil biological, chemical and physical properties were measured. Preliminary results suggest that organic farming practices can improve water quality in Midwestern tile-drained landscapes.
1. Nitrate-nitrogen (N) contamination of surface water is a major water quality concern in the upper Midwest USA. Environmental impacts associated with conventional agricultural production have encouraged producers to investigate alternative management practices, including organic farming methods. In 2011, ARS scientists in Ames, Iowa, initiated a long-term study that compares tile drainage water nitrate-N losses for a conventional corn-soybean and an organic corn-soybean-oat/alfalfa-alfalfa organic grain cropping system. ARS scientists demonstrated that between 2012 and 2014, average annual nitrate-N concentrations were lower in tile drainage water collected from the organically-managed rotation compared to the conventionally-managed rotation. Total nitrogen loss from 2012 to 2014 for the conventional rotation (79.2 kg N/ha) was nearly twice as much as from the organic rotation (39.9 kg N/ha). These results suggest that organic farming practices can improve water quality in Midwestern tile-drained landscapes.
2. Database development for crop simulation models. The Agricultural Model Intercomparison and Improvement Project (AgMIP) is an international effort to build databases and crop models that support efforts to understand and predict climate change effects on crop production at a global scale. Data representing three tillage systems (conventional tillage, strip tillage, and no-till) for a corn-soybean system have been assembled to include weather, soils, and crop growth and yield data needed to evaluate corn and soybean simulation models as part of the AgMIP. These data have been assembled for the 2010 through 2014 growing seasons, and the corn data were used to evaluate data harmonization tools capable of being able to search databases using standard nomenclature for the variables. This same development of databases has been assembled for canola trials conducted in 2013 and 2014 for evaluation of multiple canola simulation models. Canola (rapeseed) has become a major crop for production of edible oil around the world, and plays an essential role for international food security. The corn data are being made available through the National Agriculture Library.
3. Bio-energy cropping systems utilizing corn stover require additional nutrient applications. Growing crops as a bio-energy feedstock has attracted the attention of many producers; especially in the Corn Belt states. The long-term effects of both increasing grain yields and removing stover on soil nutrient cycling, physical properties, and biological activity must be understood to ensure that corn yields meet both current and future demands. After six years of a field study conducted by ARS scientists in Ames, Iowa, comparing tailored nitrogen, phosphorus, and potassium fertilizer management for several corn biomass management systems with standard fertilizer management, we were able to show that concentrations of all nutrients in the growing crop could be maintained at optimum levels within each of the crop management systems. During five of the six years the study has been conducted, differences in plant populations and tillage intensity, application of biochar, and use of cover crops did not affect corn grain or stover yields, suggesting that long-term research is needed to determine the effects of these management practices. The results of this research are providing nutrient management guidelines that maximize crop utilization and biomass yields, and will benefit commercial growers, as well as the fertilizer and emerging cellulosic ethanol industries.
4. Cereal rye cover crops preceding corn can increase incidence of corn seedling root diseases, but improved cover crop management should reduce this risk. In the upper Midwest, corn yields following cereal rye cover crops have been reduced in some years and some fields. One of the possible reasons for the yield reductions is that cereal rye and corn share some of the same root pathogens. Thus, cereal rye may be acting as a host for these pathogens and when cereal rye cover crop is terminated immediately before corn planting these pathogens may be transferred to the corn seedlings. Results from field and controlled-environment studies conducted by ARS scientists in Ames, Iowa, and Iowa State University collaborators, showed that this does occur for Pythium and Fusarium pathogens of corn. The effect of the rye cover crop on these pathogens differed among species, fields, and time after cover crop termination. Understanding the role of cover crops in disease incidence of the following corn crop will allow us to devise management strategies to overcome this risk factor. The impact of this research will be that farmers, extension personnel, crop advisors, and Natural Resources Conservation Service (NRCS) conservationists will be able to use and manage cover crops more effectively, which will lead to more cover crop adoption, less risk to corn yield, and more environmental benefits.
Acharya, J., Bakker, M.G., Moorman, T.B., Kaspar, T.C., Lenssen, A.W., Robertson, A.E. 2016. Time interval between cover crop termination and planting influences corn seedling disease, plant growth, and yield. Plant Disease. 101(4):591-600. https://doi.org/10.1094/PDIS-07-16-0975-RE.
Schenck, L.A., Bakker, M.G., Moorman, T.B., Kaspar, T.C. 2017. Effects of cover crop presence, cover crop species selection, and fungicide seed treatment on corn seedling growth. Renewable Agriculture and Food Systems. https://doi.org/10.1017/S1742170517000345.
Korucu, T., Shipitalo, M.J., Kaspar, T.C. 2018. Rye cover crop increases earthworm populations and reduces losses of broadcast, fall-applied, fertilizers in surface runoff. Soil & Tillage Research. 180:99-106. https://doi.org/10.1016/j.still.2018.03.004.
Bakker, M.G., Looft, T., Alt, D.P., Delate, K., Cambardella, C.A. 2018. Bulk soil bacterial community structure and function respond to long-term organic and conventional agricultural management. Canadian Journal of Microbiology. 64(12):901-914. https://doi.org/10.1139/cjm-2018-0134.
Dold, C., Hatfield, J.L., Sauer, T.J., Cambardella, C.A., Wacha, K.M. 2018. Hydraulic deep-core sampling impacts bulk density and carbon stock measurements. Agricultural and Environmental Letters. 3:180007. Available: https://dl.sciencesocieties.org/publications/ael/pdfs/3/1/180007.