By Jim Connolly - Turfgrass fertilizer traditionally contains one or more of the common 16 elements that are considered essential for plant growth. These elements still represent the core of most fertilizer programs and many golf courses apply only the traditional “elemental” nutrients. But there are a growing number of professional turfgrass managers applying products that contain more than just elemental nutrients.

They are using products that contain a wide variety of compounds that include amino acids, marine-plant extract, vitamins, organic acids, penetration aids, metal-complexing agents, and other non-plant food ingredients.

States are responsible for fertilizer laws and most define fertilizer as a “substance containing one or more recognized plant nutrients” (WSDA, 2010). In Washington State, for example, all other ingredients are considered Non-Plant Food Ingredients (NPFI).

NPFI may not be in the same category as a fertilizer nutrient, but they may provide various plant responses and that is why they hold such interest with many turfgrass managers. Use of these products and research on the effects of NPFI is growing. Seaweed extract is one example of a NPFI showing positive effects to plants and turfgrass. But the exact mechanisms of plant response are not completely understood. In agriculture, “Ascophylum (seaweed) extracts consistently outperformed the controls (regular crop management program) and produced better quality fruit and higher yields” (Norrie and Keathley, 2006). Turfgrass exhibits improved stress resistance due to antioxidant production when treated with seaweed extract and humic acids (Zhang, et al., 1997).   Leafs indeed absorb a lot of various substances. According to Dr. Haibo Liu from Clemson University, his research shows, “Leaves can absorb nutrients better than roots under certain conditions.”

The phrase “snake oil” has been attributed to products sold by unscrupulous salesmen to apparently dull-witted golf course superintendents. In the 1998 Green Section Record, Snake Oils, golf course superintendents are warned, “Do not buy any new product sold by individuals whose claims cannot be substantiated by extensive university research.” (Moore, 1998) Following Moore’s advice would seriously limit product selection since universities can never come close to extensively testing even a small fraction of products on the marker. Some superintendents don’t agree with waiting for research findings before purchasing products to try. Kevin Hicks, superintendent at The Coeur d’ Alene Resort Golf Course in Idaho, believes that out-of-the-box thinking is critical to his success with regard to products containing non- traditional ingredients. “There is value in university results, but their research data is spun into more sales-pitches than the products that don’t have university trials. My career and reputation is on the line every day and I must find products, tested or not, that I can use as tools to better manage my golf course” Says Hicks.

Mike Richardson and his team at the University of Arkansas are researching turfgrass response to foliar applied nitrogen. “We (turfgrass industry) are just recently getting our heads out of turf books with regard to foliar application of nutrients.  We realize horticultural and agriculture may be years ahead of us and there is a lot we don’t know.” says Richardson.   Science provides answers but practical experience and trying new concepts often leads to innovative products. Einstein said, “If we knew what we were doing we would not call it research!” Snake Oil is a phrase associated with bogus products and foolish buyers.   As it goes with many things, The Times They are a Changin’, and we now know that some snake oils contain omega 3 fatty acids that are shown to have very good health benefits. Today’s snake oil may be tomorrow’s medicine.

Another area of current debate concerns nutrient efficiency. Which part of the plant is better at absorbing nutrients, the root or the leaf?   Jim Baird of the USGA doubts that most superintendents are foliar feeding at all. He writes, “…let's not forget that foliar uptake of nutrients is minor compared to the effectiveness of the root system.” And, that in his opinion, most superintendents apply too much water per 1000 square feet and really are not foliar feeding (Baird, 2007).

According to Dr. Haibo Liu, from Clemson University, leaves can absorb a variety of substances, and quite efficiently.   “Leaves can absorb nutrients better than roots under certain conditions.” says Dr. Liu.   Conditions that affect foliar absorption include the form of nutrient, size of the molecule, time of leaf wetness, nutrient concentration, and water application rate. The form, size, and chemical properties of nutrients can be manipulated by science. Fertilizer companies often formulate nutrients with very small molecular nutrient structures and specific electrical charges that improve foliar absorption by leaves. Research shows, that under some conditions, 95% of a single nutrient can be utilized by a foliar feeding versus only 10% of the same nutrient applied to the soil and that essential and non-essential nutrients can be foliar absorbed with high efficiency (Tukey, 1958., Bukovac and Wittner,1957).

Foliar feeding is used by thousands of golf course superintendents to provide a high percentage of yearly nutrient applications, especially on putting greens.   Bruce Williams, a leading figure in the golf industry, with over 40 years of experience, has seen a lot of ways to feed turf. William’s program is similar to many superintendents’ feeding programs. “My program at Los Angeles Country Club was about 75% foliar and 25% granular. Granules were applied during aeration for the purpose of adjusting soil chemistry or adding other necessary soil amendments.”

Another question being asked relates to cost difference between using elemental nutrients, such as urea, and specialty products that may contain essential nutrients and a variety of non-plant food ingredients.   A recent report supported by the USGA, University of Maryland, and the Chicago District Golf Association, evaluated a number of biostimulant products compared to urea alone. (Settle and Doernoden, 2009)   The report states, “…that to achieve healthy looking greens with good color, plant density, and vigor, urea just might be the right thing to do.” This is a strong research summary statement! Especially for a 2 year study- where one of the years the plots were infected with dollar spot.   The results of this study are frequently used by experts to summon superintendents stop wasting money and “Get Back to the Basics”.

Contrary to the Settle report, other research reports show statistical improvements to turfgrass quality from applications of biostimulants (Mueller and Kussow, 2005).   Root development has been reported to improve from the use of some biostimulants and used with the planet growth regulator Trinexapac-ethyl. Other research shows improved color and reduced leaf senesce from the application of biostimulants (Huang and Xu, 2009).

In the end, we find that we know very little about plant physiology and the miraculous way plants work. We have a limited understanding in many areas of turfgrass growth, physiology, and biochemistry that makes definitive recommendations about the use of Non Plant Food Ingredients very difficult. Still, the use of biostimulants on turfgrass holds great potential (Karnok, 2000 ).

Research and practical experience by turfgrass managers reveals non-food plant ingredients that are sold for use on turfgrass may contain benefits beyond the use of traditional fertilizers. In the end, it is the professional turfgrass manager who will have to evaluate the available information, perform their own testing, and make decisions that are best for their future.

References Cited:

Baird, James H. 2007. Soil Fertility and Turfgrass Nutrition 101. USGA Green Section Record. September/October. 45(5): p. 1-8.

Bukovac, M.J., and Wittwer, S.H. 1957. Absorption and Mobility of Foliar Applied Nutrients. Michigan State Agricultural Experiment Station. Journal Article No. 2059.  

Huang, B., and Xu, Y. 2010.   Promoting Better Summer Performance of Creeping Bentgrass through Application of Trinexapac-ethyl and Seaweed Extract-based Biostimulants. USGA Turfgrass and Environmental Research Online. Volume 9, Number 7.

Karnock, K.J., 2000. Turfgrass Biostimulants – Are they a Viable Management Tool?

Found Online at: http://archive.lib.msu.edu/tic/mitgc/article/200052.pdf

Moore, J.F. 1998. Snake Oils. USGA Green Section Record. May/June Issue. Page 13

Mueller, S.R., and Kussow, W.R. 2005. Biostimulant influences on turfgrass microbial communities and creeping bentgrass putting green quality. Hort Science. Vol: 40.

Norrie, J. and Keathley, J.P. 2006. Benefits of Ascophylulum Nodosodum Marine-Planet-Extract Applications to Thompson Seedless Grape Production. Acta Hort. (ISHS) 727:243-248

Settle, D., and Dernoeden, P.H. 2009. Evaluation of cytokinen plant extract biostimulants, iron, and nitrogen products for their effects on creeping bentgrass summer quality. USGA Turfgrass and Environmental Research Online 8(1): 1-16

Tukey, H.B. 1958. New Ideas through Atomic Energy. Foliar Feeding of Plants. Found at: http://www.uas-cropmaster.com/pdfs/SummaryOfProject.pdf

WSDA, 2010.   Fertilizer Registration Guidance Document. PUB 90.

Zhang, Xunzhong; Ervin, E. H.; Schmidt, R. E. 2003. Journal of The American Society for Horticultural Science. July. 128(4): p. 492-496.