U.S. flagAn official website of the United States government
                    Here's how you know **Official websites use .gov**
                            
                            A **.gov** website belongs to an official government organization in the United States.
 **Secure .gov websites use HTTPS**
                            
                            A **lock** (                            
                              A locked padlock                                                      
                            
                            ) or **https://** means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.


Menu Agricultural Research Service
						
                    U.S. DEPARTMENT OF AGRICULTURE
 close



Research
                Research Home
                            National Programs
                            Research Projects
                            Scientific Manuscripts
                            International Engagement
                            Scientific Software/Models
                            Databases and Datasets
                            Office of Scientific Quality Review
            Media
                News & Features
                            Multimedia
                            Briefing Room
                            Down on the Farm
                            Press Room
                            Science in Your Shopping Cart
                            Scientific Discoveries
                            Tellus
                            Under the Microscope
            About ARS
                About ARS Home
                            Staff Directory
                            Labs and Research Centers (Map)
                            Headquarter Offices
                            Organizational Chart
                            Employee Services (REE Employees Only)
                            Office of Outreach, Diversity, and Equal Opportunity
            Work With Us
                Work With Us Home
                            ARS Vacancies at USAJOBS
                            Careers at ARS Information
                            Scientific Collaborations
                            Extramural Agreements
                            1890 Faculty Research Sabbatical ProgramSearch small
                    Search
            
            ARS Home
                                About ARS
                                Contact Us




ARS Home Research Publications at this Location





- ARS National Programs
- Search for a scientific manuscript
- Search for a research project
- ARS Software
- Programs and Projects
- Collaborations
- Subjects of Investigation
- Publications

Title:   Author  item
                                            McCarty, Gregoryitem
                                            Shelton, Danielitem
                                            Teasdale, John
  Submitted to: Plant and Soil
                                    Publication Type: Peer Reviewed Journal
                                    Publication Acceptance Date: 8/1/2000
                                    Publication  Date: 12/1/2000
                                    Citation: N/AInterpretive Summary: The use of winter annual cover crops has increased in recent years due to their ability to significantly reduce NO3- leaching during winter/spring recharge and/or provide for the nitrogen (N) demands for subsequent crop growth.  Unfortunately, no single cover crop has shown to consistently achieve both objectives.  Grasses, for  example, can significantly reduce N leaching, but generally provide little N for crop growth.  Legumes, such as hairy vetch, can supply substantial amounts of N, but their ability to reduce N leaching during winter/spring recharge is minimal. The use of grass/legume mixtures has the potential to fulfill both objectives. We found that denitrification was observed in vetch cores five days after kill as a consequence of available nitrate and high respiration rates.  Substantially lower denitrification was observed on  subsequent dates or with other treatments due to either limited nitrate availability or lower respiration rates.  Results suggest greater potential N losses from vetch than rye or rye-vetch cover crops due to rapid N-mineralization in conjunction with denitrification and leaching, prior to significant crop N- assimilation. This study supports the conclusion that a rye-vetch cover crop mixture may be superior to monoculture vetch or rye cover crops because of intermediate net N-mineralization rates resulting in decreased N leaching and denitrification losses, and better correspondence between N availability and crop N demands.
                                Technical Abstract: N mineralization, N immobilization and denitrification were deter- mined for vetch, rye, and rye-vetch cover crops using large packed soil cores.  Plants were grown to maturity from seed in cores.  Cores were periodically leached, allowing for quantification of nitrate and ammonium production, and denitrification incubations conducted before  and after cover crop kill.  Gas permeable tubing was buried at two depths in cores allowing for quantification of nitrous oxide in the soil profile.  Cover crops assimilated most soil N prior to kill. After kill, relative rates of N mineralization were vetch > vetch-rye mixture > fallow > rye.  After correcting for N mineralization from fallow cores, net N mineralization was observed in vetch and rye- vetch cores while net N immobilization was observed in rye cores. Denitrification incubations were conducted 5, 15 and 55 days after  kill and with adjustment of cores to 75% water filled pore space (WFPS).  The highest denitrification was observed in vetch cores five days after kill as a consequence of available nitrate and high respiration rates.  Substantially lower denitrification was observed on subsequent dates.  Results suggest greater potential N losses from vetch than rye or rye-vetch cover crops due to rapid N-mineralization in conjunction with denitrification and leaching, prior to signif- icant crop N-assimilation. Results were compared with denitrification incubations conducted with intact soil cores obtained from vetch, rye, and fallow field plots 7, 14, and 49 days after cover crop kill. Results were generally similar, although not directly comparable because of lower WFPS (62-66%) and fertilization.


Return to top


Connect with ARS Sign up


ARS Home
                            USDA.gov
                            Plain Writing
                            Policies & Links
                            Civil Rights Statements
                            FOIA
                            Accessibility Statement
                            Privacy Policy
                            Non-Discrimination Statement
                            Quality of Information
                            USA.gov
                            WhiteHouse.gov