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Evaluating the Potential of Winter Cover Crops for Carbon Sequestration in Degraded Soils Transitioning to Organic Production

Investigators
Grossman, Julie
Institutions
North Carolina State University
Start date
2010
End date
2011
Objective
Global concerns about the rapidly rising CO2 in the atmosphere, coupled with the promise of future payments for captured carbon, have prompted a renewed interest in soil C sequestration, especially in organic systems where application of complex organic materials is a common management practice. This project will strengthen organic production in the long-term by providing information about how to best manage cover crop residue in Southern climates during the transition process in order to retain and protect recently added carbon.

The primary long term goals of this project are: Goal (1) Evaluate common and novel cover crops for their potential to contribute to soil organic matter development in order to develop tools for conservation planners to quickly identify beneficial practices for transitioning organic farmers, and Goal (2) develop models for educating agricultural stakeholders, future extension leaders (students), and low-income urban populations about the benefits and challenges of cover crop use.

Our supporting objectives for our first goal include: Objective (1): Evaluate root and shoot contributed-C of both grass and legume cover crop species to determine C sequestration potential; and Objective (2): Select high-fixation rhizobia symbionts appropriate for use with legume cover crops with the highest potential for C contribution. The timeline and outputs for our first two research objectives include the following: Fall/Winter of 2011 and 2012 we will plant our field trials at two field sites in North Carolina, taking data in the Spring and Summer of 2012 and 2013. Rhizobia evaluation will be completed by the end of 2011. At least two manuscripts will be produced based on the findings of our research in 2013. To meet our second goal we will use a multi-tier outreach approach to disseminate the information produced by our proposed research. Specific outreach and educational objectives include:

Objective (3): Develop and pilot 5 teaching modules for urban educational farms using cover crops to develop soil fertility and organic matter in low-income neighborhoods where community gardens are located.

Objective (4): Develop a professional development extension training program for graduate students, the Young Extension Professionals (YEP) program, including two field days at the Center for Environmental Farming Systems designed and carried out in-part by graduate student trainees.

Objective (5): Develop a new course "Climate Change & Agriculture" for undergraduate and graduate students. The timeline and outputs for teaching and outreach objectives 3-5 include the following: The "Climate Change & Agriculture" course will be held twice in Spring semester of 2012 and 2013.

The YEP program offerings will be held each Fall and Spring semester over two years: Fall 2011, Spring 2012, Fall 2012, and Spring 2013. A fifth offering will be made available based on student interest. Two CEFS workshops will be offered in each summer of our project: Summer 2012 and 2013. Cover crop teaching modules will be designed by students each Fall semester of Fall 2011 and 2012, with 2-3 modules developed per class group.

More information
Non-Technical Summary: There is a critical need for information about how the effects of organic agriculture, specifically cover crop combinations, are quantified when assessments for carbon sequestration are employed to determine associated incentive payments. This project will strengthen organic production in the long-term by providing information about how to best manage cover crop residue in Southern climates during the transition process to retain and protect recently added carbon. As policy makers move in the direction of recognizing and subsidizing carbon as a key indicator of environmental services it is important to develop scientific datasets to support organic farms as leaders in this capacity. This project joins together Southeastern U.S leaders in organic agriculture research, including North Carolina State University (NCSU), the Center for Environmental Farming Systems (CEFS) and North Carolina Agricultural & Technical University (NCA&T) to respond to farmer concerns about soil carbon sequestration through a fully integrated research-, education- and extension-based project. The primary long term goals of this project are: (1) Evaluate common and novel cover crops for their potential to contribute to soil organic matter development to develop tools for conservation planners to quickly identify beneficial practices for transitioning organic farmers, and (2) develop models for educating agricultural stakeholders, future extension leaders (students), and low-income urban populations about the benefits and challenges of cover crop use. To meet our first goal we will study the contribution of cover crop plant biomass additions to soil carbon by investigating the microbial processes controlling both decomposition and stabilization of added carbon. To meet our second goal we will use a multi-tier outreach approach to disseminate the information produced by our proposed research. Specific outreach efforts include: 1) hosting 2 traditional face-to-face workshops and training opportunities for farmers, organic educators, and NRCS personnel, with particular emphasis placed on small and limited-resource farmers in the Southeast, 2) developing and piloting 5 cover crop teaching lessons for low-income urban populations using urban gardens to increase food security, and 3) designing two academic components including an upper-level oClimate Change & Agricultureo course and a unique extension training program for graduate students, the Young Extension Professionals (YEP) program. The goal of YEP is to train effective extension personnel and farmer communicators following completion of their academic program.

Approach: Objective (1): Evaluate root and shoot contributed-C of both grass and legume cover crop species to determine C sequestration potential. We will collect C- related data of cover crop treatments to help us understand how direct C contribution and indirect microbial activities leading to long-term protection and stability vary among cover crop species and management techniques commonly used in organic agriculture. We will use a split plot design on transitioning organic land at two field sites, including 4 levels of main-plot cover crop termination method (roll, mow/incorporation, mow/surface residue, burndown with herbicide). Sub-plots will be a completely randomized design including 6 levels of legume species and appropriate no-cover crop control. Direct measures of C contribution include cover crop shoot biomass, root C biomass, soil nutrients, and particulate organic matter (POM). Indirect measures of cover crop C contribution include indicators of C protection and stabilization such as bacterial:fungal biomass ratios using marker fatty acids, soil enzyme activity, dissolved organic matter (DOM), and mineralization and respiration one month after cover crop termination. Objective (2): Select high-fixation rhizobia appropriate for use with legume cover crops. We will use REP-PCR molecular characterization approaches, and traditional growth chamber assessment to assess a collection of over 800 strains of N-fixing rhizobia bacteria for hairy vetch. Objective (3): Develop and pilot 5 teaching modules for urban educational farms using cover crops to develop organic matter. The Grossman lab has established a successful partnership with an NGO focused on developing community gardens programming in two low-income neighborhoods. As part of the undergraduate Soil Agroecology/Ecological Soil Management course, students will develop 5-6 teaching modules related to cover crop management to be taught to neighborhood residents where gardens are located. Modules will be developed and tested by students in Grossman's Fall course in each of the 3 project years, and will become part of the NGO's educational curriculum. Objective (4): Develop a professional development extension training course. This project purposefully involves this project's graduate students and post-doc trainees (4), plus our SARE project's PhD student, in a unique and much needed training program to develop highly skilled extension personnel who are extremely knowledgeable about organic agriculture practices. This Young Extension Professional (YEP) program will involve extension enrichment professional development workshops over 3 years on topics necessary for successful agricultural extension. Objective (5): Develop a new course "Climate Change & Agriculture" for undergraduate and graduate students. We (Hu, Grossman) will develop a new upper-level undergraduate / graduate student course named "Climate Change & Agriculture". This course aims at developing a comprehensive understanding of the cause and effects of global climate change, its social, economic and ethical dimensions, and its impacts on the productivity and sustainability of agricultural lands.

Funding Source
Nat'l. Inst. of Food and Agriculture
Project source
View this project
Project number
NC09799
Accession number
223756
Categories
Food Defense and Integrity