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
 Crops Pathology and Genetics Research: Davis, CA
 close



    Research

                    Research Projects
                                    Publications
                                    Collaborations
                                    News
                People

                    Staff Listing
                                    Careers


        


                    Outreach Events
                        UC Davis Picnic Day
                                    Kinders go to College
                                    STEM Girls
                                    Future Scientist Program
                                    Agriculture Future of America
                                    Wallace-Carver Fellowship
                                    Young Scholars Program
                                    Annual Awards Banquet
                    About Us
                        About Us
                                    Our Mission
                                    Principal InvestigatorsSearch small
                    Search
            
            ARS Home
                                About ARS
                                Contact Us




ARS Home Pacific West Area Davis, California Crops Pathology and Genetics Research 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
- Etiology and Biology of Tree Crop Diseases
- Rice Genetics
- Sustainable Floriculture
- Sustainable Viticulture

Title:   Author  item
                                            Steenwerth, Kerriitem
                                            JACKSON, LOUISE - UCD LAND,AIR,WATR RSitem
                                            Calderon, Franciscoitem
                                            SCOW, KATE - UCD LAND,AIR,WATR RSitem
                                            ROLSTON, DENNIS - UCD LAND,AIR,WATR RS
  Submitted to: Soil Biology and Biochemistry
                                    Publication Type: Peer Reviewed Journal
                                    Publication Acceptance Date: 2/10/2005
                                    Publication  Date: 4/1/2005
                                    Citation: Steenwerth, K.L., Jackson, L.E., Calderon, F.J., Scow, K.M., Rolston, D.E. 2005. Response of microbial community composition and activity in agricultural and grassland soils after simulated rainfall. Soil Biology and Biochemistry. 37: 2249-2262.Interpretive Summary: Periodic wet-dry cycles in Mediterranean climates affect soil microbial processes, but the dynamics will vary depending on the intensity of the land use. Land use intensification (LUI) is associated with decreases in soil quality and shifts in C and N dynamics with increased tillage frequency and external chemical inputs. We previously determined LUI results in distinct microbial communities compared to less intensively managed sites. Here, our objectives were to understand how LUI affected ecosystem functions (EF) provided by the soil microbial community, and to investigate links between soil microbial community composition and EF. The California ecosystems consisted of annual vegetable crops and annual grassland in Salinas Valley, and perennial grass agriculture and native perennial grassland in Carmel Valley. In the agricultural systems, reductions in both the measures of microbial diversity and resistance of the microbial community composition to change after a perturbation were associated with lower EF, i.e., lower microbial responses to increased moisture availability. This suggests that characteristics associated with grassland soils should be considered during management of agricultural soils.
                                Technical Abstract: We explored the hypothesis that land use intensification decreases the resistance of microbial community composition (MCC) and activity to perturbation.  Soil carbon (C) and nitrogen (N) dynamics and microbial responses to a simulated rainfall were measured in grassland (GE) and agricultural ecosystems (AE). The California ecosystems consisted of annual vegetable crops and annual grassland in Salinas Valley, and perennial grass agriculture and native perennial grassland in Carmel Valley. Intact cores (30 cm deep) were collected in March 1999. After equilibration, dry soil cores (approx. -1 to -2 MPa) were exposed to a simulated rainfall of 2.4 cm, and then were measured at zero, six, 24, and 120 h after rewetting. Microbial biomass C and inorganic N did not respond to rewetting. N2O and CO2 efflux and respiration increased after rewetting in all soils, with larger responses in the grassland than in the agricultural soils. Phospholipid fatty acid (PLFA) profiles indicated that changes in MCC after rewetting were most pronounced in intensive vegetable production, followed by the relict perennial grassland. Consistent changes in specific PLFA markers did not occur across all sites. There were more similarities among microbial groups associated with PLFA markers in AE than GE. Differences in responses of microbial communities may be related to the different plant species composition of the grasslands. Agricultural intensification appeared to decrease microbial diversity, as estimated from numbers of individual PLFA identified for each ecosystem, and reduce resistance to change in MCC after rewetting. In AE, reductions in both the measures of microbial diversity and the resistance of MCC to change after a perturbation were associated with lower ecosystem function, i.e., lower microbial responses to increased moisture availability.


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