2011 Annual Report
1a.Objectives (from AD-416)
Objective 1: Evaluate land use systems over agricultural landscapes to determine the effects of management and landscape setting on N dynamics. Sub-objective 1-1. Compare N availability in grasslands and organic pasture to more intensively managed land use systems serving dairy and beef livestock production.
Sub-objective 1-2. Compare N availability in organic production to conventional production systems growing alfalfa, corn, soybean, and small grains. Sub-objective 1-3. Develop environmental and economic partial N budgets to compare grasslands, organic and conventional agronomic, and livestock production systems.
Objective 2: Develop and evaluate cropping systems for optimal biomass production that maintain or enhance soil productivity. Sub-objective 2-1. Quantify the effect of conventional and alternative biomass production strategies on soil productivity, measured by changes in soil carbon (C) and N, and total biomass and crop yield. Sub-objective 2-2. Develop energy budgets to compare energy use in biomass production systems and evaluate the use of biomass for bioenergy feedstock versus livestock production.
1b.Approach (from AD-416)
An evaluation of N dynamics including an assessment of availability, defined as mineral N forms available for plant uptake, across cropland, grassland and pasture systems will be conducted. We will evaluate alternatives to a strict C-S rotation, including perennial grasses, an annual grass hybrid, a living mulch and a cover crop, to compare the effectiveness of these strategies to mitigate potential negative impacts of harvest and to provide greater biomass and economic returns.
We investigated land-use impacts on soil nitrogen dynamics (Objective.
1)in cooperation with organic producers and other landowners. We established field experiments and assessed in situ nitrogen mineralization to compare organic and conventional cropping systems by evaluating N in similar soil types under the same crops (corn, barley, and wheat or soybean). We continued to evaluate N leaching through drainage tiles and N entering monitored or unmonitored waterways. Based on earlier results, we modified the on-farm experiment to assess perennial systems (pasture/CRP), and initiated a new study using diverse perennial mixtures to measure available N and evaluate the impact of harvesting/residue removal and fertilization on several crop and soil variables. We continued field activities initiated in fall of 2007 to develop alternative cropping systems for optimal biomass production (Objective 2). These conventional and alternative biomass production practices include five two- or six-year rotations: corn-soybean; corn/winter rye-soybean; corn/clover-soybean/clover; annual hybrid sorghum-Sudan grass–soybean; and perennial grass-grass-grass-soybean-corn-soybean. Perennial grass entries include a monoculture Switch grass and a mixed culture of Switch grass, Indian grass, and Big Blue stem. We continued to establish winter-rye cover crops following corn in the corn-soybean rotations; however due to operational difficulties and substantial yield decline of corn and soybean, we removed the red clover living mulch from the experiment. As a remedial measure, we incorporated the red clover living mulch experimental plots into the two perennial grass systems, thus providing a balanced 3yr x 3yr rotation for the experiment. Substantial snow cover during the winter season caused delayed emergence of rye, and extended water logging in early spring delayed planting. We initiated new field and laboratory studies on biomass pyrolysis of biochar residues and found no impact of earthworm populations two years after applying three different types of biochar. However, laboratory assessments suggested that negative short-term impacts may occur but depend on application rate and feedstock material. Data was compiled from on-farm studies integrating whole-farm and land-use system components and on-station evaluation of alternative production practices. Statistical analyses and simulation studies are underway to develop management strategies that improve soil productivity and enhance conservation as well as reduce economic risk.
Perennials in crop rotations improve environmental health. The current crop production system in the Chippewa River Watershed in West Central Minnesota resulted in negative environmental impact caused by soil erosion, nutrient loss, and lower water quality. Opportunities to improve this situation include reducing soil erosion, runoff, and nutrient leaching by including perennials in the crop rotation. This change in land use will improve environmental health through sustained carbon sequestration and reductions in soil erosion, runoff, and nutrient leaching. ARS researchers at Morris, Minnesota, simulated the impact of 100 years each of historical and projected weather variables, in combination with soil data and current and alternative crop rotations in 12 representative soil series located throughout the watershed. Different soil series, depending on their physical characteristics and position in the landscape, varied in their response to increasing the proportion of perennials in the crop rotation, and in their ability to reduce the negative impact of projected climate change. Farmers in the watershed can diversify current cropping systems and help mitigate the impact of future climate change by adjusting land-use to accommodate more perennials in future crop rotations. This will help develop production systems that can produce regular crops and a wide range of other ecosystem services.
Stability of crop yield in the Northern Corn Belt. Cropping systems in the Northern Corn Belt changed due to several factors such as environmental, economic, and social factors. The current system, based on the corn-soybean crop rotation, conventional tillage, and chemical inputs, may not be sustainable in the long run. ARS researchers at Morris, Minnesota, developed and verified crop rotations and management practices that reduce yield variation. We developed models and identified relationships between soil physical, chemical, and biological variables; crop rotations; management practices; and inputs in conventional and organic cropping systems. We developed a method to select management practices for a given cropping system or crop rotation in order to obtain large, stable crop yields. As a result, researchers, crop consultants and farmers will use inputs more efficiently, detect crop responses, determine trends, understand changes in yield, and assess sustainability.
Jaradat, A.A., Rinke, J.L. 2010. Nutrient homeostasis, C:N:S ratios, protein, and oil content in Cuphea seed. Seed Science and Biotechnology. 4(1)1-9.
Jaradat, A.A., Goldstein, W., Dashiell, K.E. 2010. Phenotypic structures and breeding value of open-pollinated corn varietal hybrids. International Journal of Plant Breeding. 4(1):37-46.
Jaradat, A.A. 2011. Polymorphism, population structure, and multivariate relationships among secondary traits in open-pollinated corn heterotic groups. Communications in Biometry and Crop Science. 6(1):4-20.
Jaradat, A.A., Weyers, S.L. 2011. Statistical modeling of yield and variance instability in conventional and organic cropping systems. Agronomy Journal. 103(3):673-684.
Liesch, A.M., Weyers, S.L., Gaskin, J.C., Das, K.C. 2010. Impact of Two Different Biochars on Earthworm Growth and Survival. Annals of Environmental Science. 4:1-9.