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
 Soil and Water Management Research: St. Paul, MN
 close



    Research

                    Research Projects
                                    Publications
                                    Collaborations
                                    News
                                    Software
                People

                    Staff Listing
                                    CareersSearch small
                    Search
            
            ARS Home
                                About ARS
                                Contact Us




ARS Home Midwest Area St. Paul, Minnesota Soil and Water Management 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

Title:   Author  item
                                            Clapp, Charlesitem
                                            CHEN, YONA - HEBREW UNIV. OF JERUSALEMitem
                                            HAYES, MHB - LIMERICK UNIV.item
                                            CLINE, VW - TORO COMPANYitem
                                            PALAZZO, AJ - USACOEitem
                                            MOLINA, JAE - UNIV. OF MINNESOTAitem
                                            WHITE, DB - UNIV. OF MINNESOTAitem
                                            Baker, John
  Submitted to: International Humic Substances Society Conference
                                    Publication Type: Proceedings
                                    Publication Acceptance Date: 7/21/2002
                                    Publication  Date: 7/21/2002
                                    Citation: Clapp, C.E., Chen, Y., Hayes, M., Cline, V., Palazzo, A., Molina, J., White, D., Baker, J.M. 2002. Humic substances for enhancing plant growth. International Humic Substances Society Conference. p. 328-329.Interpretive Summary: Natural humic substances, as components of soil organic matter, have played a vital role in soil fertility and environmental quality.  The multiple roles played by these materials can greatly benefit plant growth.  Examples are their contributions in plant growth enhancement, increasing fertilizer efficiency, or reducing soil compaction.  Our work indicates that plant stimulation provided by increased micro-elements iron and zinc availability, in the presence of humic substances, is the most important factor.  The results of these experiments have been shared with turfgrass scientists, horticultural specialists, and agricultural extension agents.  The impact will be to provide a simpler and less costly method for supplying required trace metals like iron and zinc to agricultural and horticultural crops, while decreasing risk of possible pollution by over-application of nutrients.
                                Technical Abstract: Studies on the effects of humic substances (HS) on plants, under conditions of adequate mineral nutrition, consistently show stimulation of plant growth. Enhancement of root growth was usually more apparent than stimulation of shoot growth. Both increase in root length and development of secondary roots have been observed for HS in nutrient solutions.  Typical response curves showed enhanced growth with increasing HS concentration, followed by a decrease in growth at high concentrations. Shoots generally showed similar trends in growth response to HS.  Agricultural and horticultural plants have continued to show stimulation effects from HS applied in the pouch experiments. Corn and soybean cultivars particularly have responded to humic acid (HA) and fulvic acid (FA) additions to nutrient solutions. Root growth and chlorophyll enhancement were especially noticed.  Favorable effects of HS have been widely reported.  Plant parameters affected are: root and shoot weight, root initiation, seedling emergence and growth, rhizosphere microbial population, nutrient uptake and flowering.  These effects were found for both HAs and FAs as well as for compost-derived HS.  In most experiments the activity of HAs was found to be similar to that of FAs, although some of our results gave higher activity for low molecular weight products.  It is concluded that growth enhancement of plants in nutrient solutions and soil by HS should mostly be attributed to the maintenance of Fe and Zn in solution at sufficient levels.  This effect is pH dependent and decreases with pH.


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