Submitted to: International Humic Substances Society Conference
Publication Type: Book / Chapter
Publication Acceptance Date: 9/1/1998
Publication Date: N/A
Citation: N/A Interpretive Summary: Natural humic substances, as components of soil organic matter, have played a vital role in soil fertility and environmental quality. The multiple parts played by these materials can greatly benefit plant growth. Examples are their contributions in plant growth enhancement, increasing fertilizer efficiency, or reducing soil compaction. Creeping bentgrass, a turfgrass, was used as a test plant for the evaluation of responses to humic substances. Results of experiments at St. Paul, Minnesota have indicated that the humic substances extracted from Minnesota peats exhibit positive effects on turfgrass growth. Dry weights of both plant shoots and roots increased in a 'growth pouch' laboratory screening method. Similar results were also found through a 'microplate' experiment with commercially- produced humic substances and Minnesota peats. Decreasing plant growth was also observed by some treatments compared with a fertilizer nutrient control. Promoting root growth rather than shoot growth, in some cases, ha been characterized as a good sign for stimulation of turfgrasses. This enhancement can help plants to resist unfavorable natural environments such as a drought or infertile soil. Our results can provide some new techniques to assist turfgrass growers and researchers in evaluating or interpreting use of humic substances on golf courses, sports turf and lawns.
Technical Abstract: Positive effects of humic substances (HS) on plant growth have previously been reported. The vital roles played by the HS include hormone-like plant growth enhancement, increasing chemical fertilizer efficiency, and reducing soil bulk density. Creeping bentgrass, a turfgrass, was used as a test plant for the evaluation of responses to HS materials. Results from 'growth hpouch' and 'microplate' experiments indicated that HS treatments have show positive effects on plant growth. The HS extracted from Minnesota peats exhibited positive effects on ryegrass in growth pouches, where both plant shoots and roots increased in dry weight. Similar results were also found in microplate experiments with commercially-produced and laboratory-grade HS. The HS extracted from Minnesota peats seemed to exhibit a significant enhancement effect on growth of both shoots and roots. Decreasing plant growth was observed by some treatments. Compared to fertilizer controls, HS Sevidently affect nutrient flow through a preferential influence on root growth. The promotion of root growth rather than shoot growth, in some cases, was characterized as a beneficial effect. Earlier root establishment would allow plants to resist stressful environments such as drought or infertile soils. Root length measurements clearly indicated that all HS treatments had higher root density than those of the controls. Greenhouse or field experiments are recommended for further confirmation of these effects.