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United States Department of Agriculture

Agricultural Research Service


Location: Soil Management Research

2009 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.

3. Progress Report
The 2009 fiscal year marks the first year of implementation in the five-year cycle of this project plan. In the investigation of land-use impacts on soil nitrogen dynamics (Objective 1), contacts were made with cooperating producers and organic and conventional cropland, grassland, and pasture land-use systems identified. Replicated field locations were surveyed by GPS and mapped. In fall of 2008, soil samples to measure soil properties were taken within pasture, grassland and conventional land use systems; the same locations were sampled monthly during the following growing season from planting through harvest, however conventional land use was in conversion to pasture and restored prairie. Substantial progress was made in evaluating soil nutrient dynamics and monitoring plant productivity. A standard laboratory protocol was established to simultaneously evaluate potentially mineralizable nitrogen (N) and carbon (C). Progress was also made in measuring N and P inputs and exports from the land-use systems under investigation as necessary for developing whole-field/farm nutrient balances. Field activities to develop beneficial cropping systems for optimal biomass production (Objective 2) were initiated in Fall of 2007 with soil sampling to measure baseline soil properties. The 2008 growing season was a successful first year for conventional and alternative biomass production practices, including 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. Switchgrass and a perennial grass mix of switchgrass/Indian grass/Big Blue stem were used in two separate grass rotations, and winter-rye cover crops and red clover living mulches used in corn-soybean rotations; all were successfully established. Basic soil properties, nutrients, particulate organic matter, and plant nutrients and biomass were evaluated on the total of 40 experimental plots. In addition to the 40 controlled on-station research plots, an on-farm perennial system planted for biomass production was incorporated into the project and evaluation of soil and plant dynamics conducted. This on-farm perennial biomass system study bridges both objectives in the project plan by combining on-farm land-use and bioenergy production aspects. The on-farm studies integrating whole-farm and land-use system components and on-station evaluation of alternative production practices that may mitigate loss of soil C contribute to the national action plan. The on-farm and on-station research will contribute to development of management strategies that improve soil productivity and enhance conservation as well as reduce economic risk. Additionally, these projects will contribute to development of bio-based energy production systems, and development of new technologies, in particular nutrient and energy models, to evaluate the success of diverse production strategies and on-farm implementation.

4. Accomplishments
1. Social and political factors influence agricultural systems. If agriculture is to be sustainable, it is critical to understand how it is affected by social and political factors. A panel of experts was surveyed to identify the most important social and political influences on U.S. agriculture. Although the panelists often had contrasting views about the importance of some factors, there was strong agreement on many of them. Globalization and low margins that require increased scale and efficiency were identified as the two most important factors affecting agriculture. This research provides agricultural scientists with a better understanding of social and political effects on agriculture resulting in the development of agricultural systems that will be accepted and used by farmers. This research also provides information needed by social scientists and policy makers in developing policies that lead to more sustainable agricultural systems.

2. Conservation practices improve the soil resource. Conservation practices are needed to counteract decreased soil organic matter, degraded soil structure, increased soil erosion, increased surface and groundwater contamination, and increased production costs of intensive short rotation cropping systems that have been assisted by the availability of synthetic pesticides and fertilizers since the mid-20th century. Conservation practices including multi-crop rotations (four year corn-soybean-wheat/alfalfa-alfalfa), reduced tillage and other reduced inputs (no pesticides in organic systems) were implemented and shown to improve soil fertility, including nitrogen availability and carbon content, improve corn mineral nutrient composition, and in many cases overall yields. Demonstration of these research findings has been provided through scientific publications, presentations and farmer outreach. Through increased awareness and demonstration of the benefits of conservation practices greater implementation of these practices by producers can be achieved. Greater use of these practices will improve the environment and economic sustainability of farming systems.

Review Publications
Riedell, W.E., Pikul Jr, J.L., Jaradat, A.A., Schumacher, T.E. 2009. Crop Rotation and Nitrogen Input Effects on Soil Fertility, Maize Mineral Nutrition, and Seed Composition. Agronomy Journal. 101:870-879.

Archer, D.W., Dawson, J., Kreuter, U.P., Hendrickson, M., Halloran, J.M. 2008. Social and Political Influences on Agricultural Systems. Renewable Agriculture and Food System. 23(4):272-284.

Last Modified: 10/19/2017
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