Location: Agroecosystems Management Research2017 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.
With research addressing 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 with a 30-inch row spacing, 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 fourth 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. Including a cereal rye cover crop in a continuous corn production system did not reduce average grain yield, with or without corn plant residue harvest. Soil analyses indicated no consistent changes after five years of plant residue harvest. Differences in tillage intensity and application of biochar did not affect corn grain or biomass yields during this fourth year of the 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 were taken both last fall and this spring. Tile drainage samples were collected when there was flow and analyzed for nitrate and ammonia. Soybean planting was successfully completed this spring, and no nitrogen was applied at or after planting. In corn years, N fertilizer in the no-till plots is applied after planting at rates based on the late spring soil nitrate test. Data from the previous experiment is being analyzed and written up. In other experiments examining corn seedling root diseases following cereal rye cover crops (Objective 1), data were analyzed from controlled environment experiments, a research paper was submitted and other research reports and papers are being prepared. Experimental treatments examined effects of fungicide treated and untreated corn seed after cereal rye and different cover crop species effects on corn seedling diseases. At one field site, cereal rye, camelina, and hairy vetch are being examined 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 being examined for their effect on corn seedling diseases and subsequent corn growth. The first year was completed last fall and the second year is in progress. Cover crop biomass, corn emergence, corn population, seedling root disease incidence, and plant height were measured. Data from previous field experiments are being analyzed and research papers are being prepared with one paper completed. A field experiment comparing organic and conventional crop rotations and their effects on agronomic, soil and environmental parameters (Objective 2) was continued into a fifth year. In addition to crop growth and yield, tile drainage water flow, drainage water nitrate, dissolved organic carbon (DOC), and dissolved organic nitrogen (DON) concentrations, growing-season CO2 flux, 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. Cereal rye cover crops preceding corn can increase incidence of corn seedling root diseases, but improved cover crop management should reduce this risk. Cereal rye cover crops in corn-soybean rotations have been shown to significantly reduce erosion, decrease losses of N and P, and increase soil organic matter; however, corn yields following cereal rye cover crops can be reduced during some years and some fields. One possible reason for the yield reductions is that cereal rye may be acting as a host for pathogens which can be transferred to corn seedlings after rye termination. ARS scientists in Ames, Iowa, and university collaborators showed that this does occur for Pythium and Fusarium, fungal pathogens of corn, in field and controlled environment studies. Additionally, they showed that less infection occurred when the interval between termination of a rye cover crop with herbicides and corn planting was increased to greater than 10 days. Understanding the role of cover crops in disease incidence of the following corn crop will enable the development of 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.
Hammac II, W.A., Stott, D.E., Karlen, D.L., Cambardella, C.A. 2016. Crop, tillage, and landscape effects on near-surface soil quality indices in Indiana. Soil Science Society of America Journal. 80:1638-1652. doi:10.2136/sssaj2016.09.0282.
Acharya, J., Bakker, M.G., Moorman, T.B., Kaspar, T.C., Lenssen, A.W., Robertson, A.E. 2017. Time interval between cover crop termination and planting influences corn seedling disease, plant growth, and yield. Plant Disease. 101(4):591-600. doi: 10.1094/PDIS-07-16-0975-RE.
Bakker, M.G., Moorman, T.B., Kaspar, T.C., Manter, D.K. 2017. Isolation of cultivation-resistant oomycetes, first detected as amplicon sequences, from roots of herbicide-terminated winter rye. Phytobiomes Journal. 1(1):24-35. doi: 10.1094/PBIOMES-10-16-0011-R.