Location: Agroecosystems Management Research2016 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), it was determined that after the third 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. Differences in tillage intensity, application of biochar, and use of cover crops did not affect corn grain or biomass yields during this third year of the study. At the Kelly tile water monitoring site (Objective 1) oat and winter 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 and ammonia. Corn planting was successfully completed this spring, and all nitrogen was applied at or after planting. In experiments examining corn seedling root diseases following cereal rye cover crops (Objective 1), data were analyzed from controlled environment experiments and research reports and papers are being prepared. Experimental treatments examined effects of fungicide treated and untreated corn seed, different intervals between cereal rye termination and corn planting, and different methods of cereal rye termination. At one field site, fungicide treatments and different intervals between cereal rye cover crop termination and corn planting were examined and the second year of field studies completed. Corn emergence, corn population, seedling root disease incidence, and plant height were measured. Data are being analyzed and research reports and papers are being prepared. New experiments were established at two field sites after harvest last fall. At one site, the effect of winter camelina, winter rye, and hairy vetch cover crops on corn and soybean growth, yield, and seedling disease was examined. At the second, corn response to different timing of N fertilizer applications after a winter rye cover crop was examined. In both experiments spring cover crop biomass and corn population and growth were measured. Environmental impacts associated with conventional agricultural production have encouraged producers to investigate alternative management practices, including organic farming methods. In 2011, a long-term study was initiated (Objective 2) 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. Scientists demonstrated that between 2013 and 2015, tile drainage water nitrate-N concentrations exceeded the 10 ppm drinking water standard 76% of the time in conventional C-S and 26% of the time in the organic C-S-O/A-A rotation. In 2015, tile nitrate-N concentrations in the four-year organic rotation were less than 5 ppm for the entire year. Total nitrogen loss from 2013 to 2015 for the conventional rotation (91.0 kg N/ha) was more than twice as much as from the organic rotation (43.1 kg N/ha). These results suggest that organic farming practices can improve water quality in Midwestern tile-drained landscapes. Water use by corn and soybean systems has been evaluated (Objective 3), using energy balance techniques coupled with eddy correlation equipment. These results were evaluated for 10 years of data in central Iowa to determine the seasonal patterns of water use in relationship to weather and crop growth. These results were coupled with net primary productivity of corn and soybean to determine the effect of water availability. Net primary productivity was increased when soil water was below saturation in the early spring. These results were also observed in an analysis of yield gaps for corn and soybean across the Midwest where yield gaps were observed in years with excessive precipitation in the spring and in years with below normal rainfall in July and August. Management of soil water is critical to maintaining attainable yield. These data were also used for an intercomparison of crop simulation models for their ability to accurately predict evapotranspiration across multiple years. These intercomparisons have revealed a large variation among models compared to the observed results and efforts are being directed toward improvement of the evapotranspiration component of crop simulation models.
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 have been reduced in some years and some fields. One possible reason for the yield reductions is that cereal rye may be acting as a host for these pathogens which can be transferred to corn seedlings after rye termination. ARS scientists in Ames, Iowa, showed that this does occur for Pythium and Fusarium, fungal pathogens of corn, in field and controlled environment studies. 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.
Kaspar, T.C., Bakker, M.G. 2015. Biomass production of 12 winter cereal cover crop cultivars and their effect on subsequent no-till corn yield. Journal of Soil and Water Conservation. 70(6):142A-154A. doi: 10.2489/jswc.70.6.142A.
Basche, A.D., Archontoulis, S., Kaspar, T.C., Jaynes, D.B., Parkin, T.B., Miguez, F. 2016. Simulating long-term impacts of cover crops and climate change on crop production and environmental outcomes in the midwestern United States. Agriculture, Ecosystems and Environment. 218:95-106. doi: 10.1016/j.agee.2015.11.011.
Sherrard, M.E., Joers, L.C., Carr, C.M., Cambardella, C.A. 2015. Soil type and species diversity influence selection on physiology in Panicum virgatum. Evolutionary Ecology. 29(5):679-702. doi: 10.1007/s10682-015-9770-y.
Martinez-Feria, R., Kaspar, T.C., Wiedenhoeft, M.H. 2016. Seeding date affects fall growth of winter canola (Brassica napus L. ‘Baldur’) and its performance as a winter cover crop in central Iowa. Crop, Forage & Turfgrass Management. 2(1). doi: 10.2134/cftm2015.0181.
Basche, A.D., Kaspar, T.C., Archontoulis, S., Jaynes, D.B., Sauer, T.J., Parkin, T.B., Miguez, F. 2016. Soil water improvements with the long-term use of a winter rye cover crop. Agricultural Water Management. 172:40-50. doi: 10.1016/j.agwat.2016.04.006.
Bakker, M.G., Acharya, J., Moorman, T.B., Robertson, A., Kaspar, T.C. 2016. The potential for cereal rye cover crops to host corn seedling pathogens. Phytopathology. 106:591-601.
Hongthanat, N., Kovar, J.L., Thompson, M.L., Russell, J.R., Isenhart, T.M. 2016. Phosphorus source – sink relationships of stream sediments in the Rathbun Lake watershed of southern Iowa, USA. Environmental Monitoring and Assessment. 188(8):453. doi: 10.1007/s10661-016-5437-6.
Wight, J.P., Waldron, G.J., Gatson, L.A., Blazier, M.A., Kovar, J.L. 2015. Mobility of poultry litter phosphorus in a Coastal Plain forest soil. Soil Science. 180(3):124-133.
Felicien, W.L., Wight, J.P., Gaston, L.A., Blazier, M.A., Kovar, J.L. 2016. Phosphorus runoff from Coastal Plain forest soil in Louisiana. Communications in Soil Science and Plant Analysis. 47(10):1283-1295.
Reeve, J., Hoagland, L., Villalba, J., Carr, P., Atucha, A., Cambardella, C.A., Davis, D.R., Delate, K. 2016. Organic farming, soil health, and food quality: considering possible links. Advances in Agronomy. 137:319-367. doi: 10.1016/bs.agron.2015.12.003.