Location: Agroecosystems Management Research2014 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.
Objective 1. Research addressing corn grown as a bio-energy feedstock under a variety of management systems, including continuous corn with a 30-inch row spacing, corn rotated with soybean, and corn rotated with alfalfa, all under standard fertility management, and a continuous twin-row, high-population treatment with increased nutrient additions, we found that after the first growing season, potassium was the most limiting nutrient for the growing crop. This suggests that fertilizer application rates, placement, and timing should be adjusted to meet the needs of the four management scenarios. Differences in plant populations and tillage intensity, application of biochar, and use of cover crops did not affect grain or biomass yields during this first year of the study. Oat and winter 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. Corn planting was successfully completed this spring, and all nitrogen was applied at or after planting. Management data and water, plant, and soil data are being stored in a shared directory. With three runs of controlled environment experiments conducted in the first 12 months, growth of corn following cereal rye sprayed with glyphosate was evaluated for fungal root infection and plant growth. Additional experiments examined corn growth and root infection following cereal rye, canola, and hairy vetch. A field site was established and cereal rye, canola, and hairy vetch cover crops were established after soybean harvest. Because of the unusually severe winter weather, only the cereal rye cover crop survived the winter. Corn emergence was documented, and corn plants have been sampled and assessed for root diseases and early growth. Objective 2. In an organic production system, tile water flow was continuously monitored and flow meters were manually checked every week. Collection of tile water samples for the 2013 growing season began March 13, 2013. Flow ceased in mid-July due to extremely dry conditions and no tile water samples were collected after July 17, 2013. Collection of tile water samples for the 2014 growing season began April 28, 2014. Tile water samples will be collected every week until November 2014, provided tile water flow continues. Soil was leveled, and compost was applied to organic corn and oat plots April 25, 2013. Organic oats and alfalfa were direct drilled in April 2013. Deep soil cores were collected to a depth of 120 cm on April 25, 2013. Corn and soybeans were planted in organic and conventional plots on May 15, 2013. Nitrogen fertilizer and herbicide were applied to conventional plots in June 2013. Weeds controlled in organic corn and soybean plots with rotary hoe and cultivation as needed through July 2013. Soil profile water measurements were initiated after the final cultivation for weed control in 2013. Surface soil samples were collected post-harvest of fall 2013 for soil quality analysis. Compost was applied to organic corn and oat plots in April 2014. Organic oats and alfalfa were direct drilled on April 10, 2014. Deep soil cores were collected to a depth of 120 cm on April 10, 2014. Alfalfa plots were moldboard plowed on April 11, 2014. Plots were disked and seedbed prepared for planting on May 8, 2104. Corn and soybeans were planted in organic and conventional plots on May 29, 2014. Soil and water samples are currently being analyzed. Objective 3. Progress has focused on the evaluation of the water balance component in crop growth models and data sets are being assembled across multiple sites and crops to evaluate the evapotranspiration rates in different corn and wheat models. Objective 4. In support for the Midwest Climate Hub, assembly of information on crop production across the Midwest has been completed to determine the response to different weather variables in order to assess the vulnerability to different climate variables. These data are being used to develop potential adaptation strategies for agriculture to address these vulnerabilities.
1. Improved understanding of the impact of changing climate on corn and soybean productivity. Plant interactions with the environment have been evaluated through the use of reflectance observations to quantify the growth response and couple these observations with the measurement of carbon dioxide and water vapor exchange. These studies have been conducted over corn and soybean canopies and encompass the complete growing season from planting to harvest. The reflectance data have been combined into various vegetative indices to estimate the light interception during the growing season and the changes in leaf area and biomass accumulation. The light interception data have been used to quantify light-use efficiency and relate to carbon dioxide exchange and water vapor exchanges for both corn and soybean. These data have shown that periods of water stress and temperature extremes during the growing season impact the rate of growth because of a reduction in carbon accumulation by the crop. An analysis of the carbon dioxide exchange revealed that as nighttime temperatures increased there was a decrease in the net carbon dioxide fluxes. Data sets on both corn and soybean have been used for inter-comparison of corn and soybean simulation models. These combined data sets allow for a quantification of the impact of changing climate on plant growth and productivity and the improved understanding of these effects on corn and soybean are being incorporated into improvements in crop simulation models. This research is providing improved management guidelines that maximize crop productivity, and will benefit commercial growers, as well as consultants and Cooperative Extension personnel.
Young, C.J., Liu, S., Schumacher, J.A., Schumacher, T.E., Kaspar, T.C., McCarty, G.W., Napton, D., Jaynes, D.B. 2014. Evaluation of a model framework to estimate soil and soil organic carbon redistribution by water and tillage using 137Cs in two U.S Midwest agricultural fields. Geoderma. 232:437-448. Available at: http://www.sciencedirect.com/science/journal/00167061/232.
Karlen, D.L., Kovar, J.L., Cambardella, C.A., Colvin, T.S. 2013. Thirty-year tillage effects on crop yield and soil fertility indicators. Soil & Tillage Research. 130:24-41.
Karlen, D.L., Cambardella, C.A., Kovar, J.L., Colvin, T.S. 2013. Tillage and crop rotation effects on soil quality in two Iowa fields. Soil & Tillage Research. 133:54-64.
Stott, D.E., Cambardella, C.A., Karlen, D.L. 2014. Assessment of near-surface soil carbon content across several U.S. cropland watersheds. In: Hardemink, A.E., McSweeney, K. (eds.) Soil Carbon. Cham, Zug:Springer International Publishing. p. 249-256.
Johnson, J.M., Acosta Martinez, V., Cambardella, C.A., Barbour, N.W. 2013. Crop and soil responses to using corn stover as a bioenergy feedstock: Observations from the Northern US Corn Belt. Agriculture. 3:72-89.
Stott, D.E., Karlen, D.L., Cambardella, C.A., Harmel, R.D. 2013. A soil quality and metabolic activity assessment after fifty-seven years of agricultural management. Soil Science Society of America Journal. 77(3):903-913.