Learn how agriculture and forestry can reduce greenhouse gases

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Learn how farms can help reduce nitrous oxide (N2O – a potent GHG) in cropping systems– with a focus coordinating organic and synthetic N use on fields with Dr. Armen Kemanian and Dr. Quirine Ketterings March 8 from 9 to 11 a.m.

Kemanian will present “Organic Nitrogen Management for Greenhouse Gas Reduction in Agroecosystems: Between a Gentle Seesaw and a Catapult” at 9 a.m. followed by Ketterings’s presentation of “Documenting and Managing Field Nitrogen Use for Greenhouse Gas Reduction.” Register here.

Kemanian, professor, Production Systems and Modeling, Department of Plant Sciences at Penn State University, will talk about nutrient inputs to agricultural soils as animal manure or green cover crops can add large quantities of co-located labile carbon (C) and nitrogen (N).

Animal manure is often applied in cropland around CAFOs, and animal and cover crops are often used as fertility inputs in organic agriculture. These organic amendments are often considered slow-release fertilizers for N (when low in ammonium) when compared with synthetic fertilizers, because organic N needs to be mineralized by soil microbes for that N to become available to plants.

Ideally, when N mineralization and crop N uptake are well balanced, mineral N does not accumulate in the soil. One can visualize the process as a conceptual seesaw that goes down on one end due to N mineralization that adds mineral N, but that is gently returned to the horizontal position through N uptake that removes the mineralized N; however, it is challenging to manage annual crop production on such bucolic rhythm. When considering nitrous oxide (N2O), a powerful greenhouse gas, the gentle seesaw may well be a catapult. Why? Mainly for two reasons. First, easily decomposable residues can trigger high microbial activity that consumes oxygen (O2) and creates hypoxic pockets (or layers) in the soil while organic N is being mineralized. Second, the composition of the organic amendments is hard to control, in part because the composition of cover crops varies and in part because the composition of manure varies.

A rational response by farm operators is to overshoot the application rate to avoid N shortages. These two conditions have the potential to favor large N2O emissions in bursts resembling catapult releases, because without fast mineral N by N uptake (or even with it) N mineralization is not lowering a seesaw but tensing and loading the denitrification catapult.

In this seminar, Kemanian presents field data obtained by their group in Central Pennsylvania and in Sardinia, Italy, that indicates that large N2O emissions do happen in cover-cropped and manured soils, particularly with inversion tillage that buries and packs manure or cover crop residues in a thin soil layer.

Research suggests that controlling the rate and timing of organic input additions, as well as preventing the co-location of legume cover crops and manure, could mitigate N2O emissions.

At 10 a.m., Ketterings, professor of Nutrient Management in Agricultural Ecosystems at Cornell University, will present “Documenting and Managing Field Nitrogen Use for Greenhouse Gas Reduction.”

“Adaptive Management” is an iterative strategy where farmers identify opportunities for improvement in production and environmental footprints, evaluate a management change on their own farm, through on-farm research and/or annual performance assessments. Whole farm nutrient mass balance (NMB) assessments is such an annual performance tool at the whole farm level while field nutrient balances are evaluation approaches at the field or within-field scale.

The adaptive management strategy for field crop management introduced in New York in 2013 affords farm autonomy and decision-making for site-specific problem-solving and tracks issues and successes. When farms share results of the on-farm evaluations, successful strategies can be expanded to more fields and farms.

Combined, anonymized data from participating farms can help identify practices and policies that incentivize improvements over time. While these whole farm and field-level tools were developed for nitrogen and phosphorus management with focus on water quality impact, reduction of N use will also reduce nitrous oxide emissions – a potent greenhouse gas.

About the presenters

Kemanian’s research program seeks to develop and promote productive and environmentally friendly agroecosystems. His research program combines model development and application with foundational research on the carbon and nitrogen cycle, biomass crops and polycultures deployment and agroecosystem and landscape design. Understanding, modeling and developing technologies to control soil carbon storage and nitrous oxide emissions have been a major component of Kemanian’s research portfolio.

Ketterings established and leads the Cornell Nutrient Management Spear Program (nmsp.cals.cornell.edu), the college’s applied research, teaching and extension program for field crop fertilizer and manure management, that aims to improve farmers’ awareness of soil fertility management and aid in the development and implementation of agronomic and environmentally sound nutrient management practices at dairy and other livestock farms, as well as cash grain operations. The NMSP leads the release of tools to integrate and apply accumulated knowledge about crop nutrient guidelines to optimize crop yield while minimizing risk to the environment.

Recordings from these events will be posted about seven days after the event and may be accessed at blogs.cornell.edu/workinglands/events-resources/#Webinar_Recordings.

By martha

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