Project : USDA ARS

ARS Home » Midwest Area » St. Paul, Minnesota » Soil and Water Management Research » Research » Research Project #431860

Research Project: Increasing the Productivity and Resilience to Climate Variability of Agricultural Production Systems in the Upper Midwest U.S. while Reducing Negative Impact on the Environment

Location: Soil and Water Management Research

2018 Annual Report

Objectives
1. Assess the environmental impacts of crop management practices that have the potential to improve soil health and decrease greenhouse gas emissions in the Upper Midwest. a. Develop a perennialized row crop system that reduces the environmental footprint of agriculture and improves its resilience, without adverse impacts on water usage and profitability. b. Develop new knowledge regarding soil nitrogen cycling and nitric and nitrous oxide production mechanisms. c. Develop new knowledge of chemical triggering compounds of microbial activity. 2. Increase nutrient use efficiency and reduce nutrient losses to leaching, runoff and atmospheric emissions in Upper Midwest cropping systems. a. Develop improved methods to quantify and to reduce losses of reactive N gases from fertilized cropping systems. b. Evaluate manure management practices for improvement of nutrient cycling and reduction of reactive nitrogen losses on large dairies.

Approach
All the objectives of this project have a common focus on quantifying the impacts of management practices, including crop rotation/cover crops, irrigation, and synthetic N fertilizer or manure amendments, on GHG emissions and nutrient availability for crop uptake or susceptibility to loss to the environment. The different objectives complement each other in several ways. In order to gain insights from multiple perspectives, the methods for each objective range across scales, including large field and larger plot studies (sub-objective 1a); replicated small-plots (2a); soil column mesocosms (2b); and laboratory microcosms (1b, 1c). The same set of soil types representing a range of Minnesota agricultural soils from across the state, including soil from both field experiments (1a and 2a), will be used in the microcosm and mesocosm experiments (1b, 1c and 2b). Thus, results from the three laboratory experiments each of which have different primary objectives, will inform and help to interpret results of the other lab studies; and results from the lab experiments under more controlled conditions will inform results of the field experiments that are subject to dynamic climate conditions. Both of the field experiments (1a and 2a) will measure greenhouse gas emissions and ammonia volatilization losses from cropping systems under similar soil types (the same soil series) but with different management regimes, which may also allow for cross-site comparison of results. This research also complements efforts within several national projects and initiatives, including the Greenhouse Gas Reduction through Agricultural Carbon Enhancement (GRACEnet), Resilient Economic Agricultural Practices (REAP), Dairy Agro-ecosystem Working Group (DAWG) and Long-Term Agricultural Research (LTAR) networks; and as such will involve collaboration with several colleagues from other ARS locations, universities and other organizations.

Progress Report
Sub-objective 1a: Data were analyzed from the first year of an experiment designed to determine the nitrogen (N) requirement for corn grown in a kura clover living mulch. Results showed that in the first year of planting corn into the clover stand, there was no need to add N fertilizer to optimize grain yield. In second-year corn, there was no benefit beyond adding 107 lb N ac-1, which is significantly less than the N recommendations provided by the Minnesota Extension Service. In addition, kura clover seed that had been harvested from an experimental field was cleaned, tested, and provided to potential seed producers, with the goal of increasing the amount of available seed. Finally, an experiment was initiated to determine the feasibility of using hydroseeding for establishment of a kura clover stand. Sub-objective 1b: The second round of microcosm experiments initiated last year were expanded to include five temperatures (5, 10, 15, 23 and 30o C). All of the experiments were completed. Data analysis is underway. Also extracted DNA from selected soil samples from the experiments and shipped the extracts to our collaborators at ARS, Beltsville and University of Maryland, who will investigate treatment effects on microbial DNA sequences. Additional laboratory incubation experiments were established to attempt to isolate biological and non-biological sources of nitrous oxide production in soil following amendment with organic materials using various means of soil sterilization, including mercuric chloride and gamma irradiation in collaboration with University of Minnesota researchers. These incubation experiments are continuing. Sub-objective 1c: A laboratory methodology was developed to identify headspace volatile organic compounds (VOCs) during soil and residue mineralization studies. The technique was used to observe VOC production during incubation of soil with and without addition of fresh corn residue. When soil and corn residue were incubated together, the most abundant volatile organic compounds were fatty acids, ketones and aldehydes. These results indicated that microbial decomposition of fresh corn residues leads to a different VOC signature than degradation of native soil organic matter by itself. The incubation methodology is being further developed using a pre-concentration step with solid phase micro-extraction fibers to improve compound identification and detection limits. It was also found that the addition of biochar to soil influences the distribution and absolute concentration of VOCs. The ability of VOCs to suppress microbial N2O and CO2 production is also being examined. Sub-objective 2a: Obtained extramural funds which allowed us to substantially expand the original project plan design from a single field site comparing three contrasting nitrogen management treatments, to three field sites (corn at Saint Paul, corn at Becker, and potato at Becker) each comparing seven treatments over two growing seasons. The additional funds also allowed us to include measurement of soil-water nitrate concentrations in below-root-zone samples and additional plant analysis to the matrix of measurements. The experiments were successfully established, the crops are being managed, and intensive soil, water, gas and plant sampling are underway. This experiment is being conducted with support from Eurochem Agro, and in collaboration with University of Minnesota researchers. Operation of the automated flux chamber system for semi-continuous measurement of greenhouse gas fluxes encountered some delays due to electrical problems which are currently being repaired, and expect the system to be operating at the Saint Paul site before the end of the current growing season. Sub-objective 2b: A column leaching experiment to evaluate losses of nitrogen (N) and phosphorus (P) from manure and non-manure sources on a range of soils has been completed. Sample analysis and data analysis are in process. Related experiments investigating effects of temperature on nutrient release from dairy manure to water, and effects of temperature and dairy manure placement within a snowpack on P and N release, were also completed. This research is being done in collaboration with faculty researchers from the University of Minnesota and an ARS researcher in Madison, Wisconsin.

Accomplishments
1. Nitrous oxide emissions are likely to increase in a warmer world. Emissions of nitrous oxide (N2O) from fertilized soil are an indicator of reduced nitrogen (N) use efficiency, which increases farmer production costs and has environmental impacts. Nitrous oxide is also a potent greenhouse gas (GHG) and important ozone-depleting gas. A key question is how N2O emissions will respond to expected changes in global climate. A unique 6-year data set of N2O concentrations measured at a tall radio tower was used in conjunction with modeling to estimate regional N2O emissions within the US Corn Belt. Annual N2O emissions were highly sensitive to climatic variations; in the warmest spring, 2012, more than 7% of the N applied was emitted as N2O, nearly double the expected rate. Factoring in expected trends in climate and N fertilizer use, it was estimated that regional N2O emissions will substantially exceed previous projections in the coming decades. This represents an additional challenge to the already difficult task of reducing N2O emissions and other N losses from agricultural production systems.

U.S. DEPARTMENT OF AGRICULTURE

Soil and Water Management Research: St. Paul, MN