2010 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.
The 2010 fiscal year marks the second year of implementation in the 5-yr cycle of this project plan. The investigation of land-use impacts on soil nitrogen dynamics (Objective.
1)is being achieved with the cooperation of organic producers and other land owners. In situ and potential nitrogen mineralization assessments were continued across organic and conventional cropland, grassland, and pasture land-use systems. Field activities to develop beneficial cropping systems for optimal biomass production (Objective.
2)initiated in Fall 2007 have been continued. 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 grasses being grown are a monoculture Switchgrass and a mixed culture of switchgrass, Indian grass, and Big Blue stem. Winter-rye cover crops and red clover living mulches are being tested with corn-soybean rotations. Although perennial grasses have been established, weed pressures have reduced their biomass. Red clover has had a robust establishment and hasn’t needed reseeding since the first year; however, red clover continued to negatively affect crop yields; management options are being implemented to reduce red clover competition. It was found that residue removal of corn stover had a positive effect on the establishment of the winter rye clover. Research progressed with an on-farm perennial system experiment planted for biomass production assessments; four nitrogen application treatments were applied in the second establishment year.
Biophysical constraints and ecological compatibilities of diverse agro-ecosystems. Climate change will disrupt many agro-ecosystem functions, alter their capacity to provide goods and services and render them more susceptible to degradation. Strategies are needed to help agro-ecosystems to become sustainable and be able to respond or adapt to climate change. ARS researchers at Morris, MN, and Brookings, SD, determined that stability and resilience are necessary qualities of agricultural production systems that can adapt to climate variability. Diversifying, incorporating crop genetics and properly managing natural resources can improve production systems. Farmers, crop consultants and agronomists will benefit from using potential adaptation and mitigation strategies to intensify sustainable agricultural production, and optimize and diversify conventional and organic agro-ecosystems.
Land application of biochar produced from pyrolysis should be approached with caution. Biochar created by pyrolysis, a chemical breakdown of material with heat, pressure and low oxygen, might be able to improve soil fertility and sequester carbon if put on the land. However, some biochars may contain potentially toxic compounds carried over from the feedstock, for example, poultry litter. With the use of laboratory incubations, ARS researchers at Morris, MN, discovered poultry litter in high concentrations killed earthworms; however, biochar made from pine chips did not harm earthworms. This research was the first indication that a biochar could cause harm to a soil organism. Recommendations for proper use of biochar as a soil amendment are needed. This research generates information researchers and policymakers need to determine recommendations and regulate use of biochar made by pyrolysis for land application.