World Fertilizer - 6

NEW ORLEANS (DTN) -- When most people think of fertilizers, the big three -- nitrogen, phosphorus and potash -- usually are the nutrients that jump to mind. If you are even more familiar with fertilizers, maybe micronutrients like sulfur, zinc or even boron pop into your mind.

What about silicon (Si) as a nutrient?

If you don't know anything about silicon as a fertilizer, you are not alone. In a presentation at the 2017 Fertilizer Outlook and Technology Conference held in New Orleans in mid-November, Tania Raugewitz, director of fertilizer marketing and sales for Harsco Metals and Minerals, laid out the groundwork for understanding this element as a plant nutrient.

CORRECT FORM NEEDED

Silicon is the second most abundant element in the soil after oxygen and makes up approximately 28% of the earth's crust. It is ubiquitous since it is everywhere, she said.

Most is widely distributed as silica or alumino-silicates -- better known as rocks and sand. The problem is silicas and silicates are they not available to the plant as a nutrient in this form.

Raugewitz said plants can only absorb silicon as a monosilicic acid. In addition, plants use specific silicon transporters only found in the roots and not in plant leaves.

Silicon has many positive benefits, according to Raugewitz.

For the plant, the nutrient can enhance growth, increase yields and improve quality, she said. Silicon can promote mechanical strength, as well as photosynthesis in plants, and help with resistance to insufficient sunshine or shading. Research has also shown it helps with resistance to drought stress, as well as biotic stress (disease, pest), and promotes nutrient efficiency. She added there is also alleviation of stress from mineral toxicity.

In the soil, silicon also works to improve several different issues, Raugewitz said. The nutrient can enhance soil stability, improve soil structure and phosphorous availability and lessen resistance to metal toxicity.

"Under less-than-ideal growing conditions, certain silicon products can restore soil tilth and fertility," Raugewitz said.

Soils that are in tropical regions of the world, or are generally wet, can see significant yield and general agronomic advantages from applying silicon. Adding silicon can help all types of crops, including field crops, horticultural crops and turf, she said.

Research from across the world shows there are effects on both plant yield and quality of applying silicon. Yields can be increased anywhere from 4% to 50% in these studies with various field crops and vegetables, she said.

Several different silicon fertilizers are on the market, she said. Among the most common products are calcium silicate, calcium magnesium silicate, potassium silicate and sodium silicate.

CHALLENGES FOR SI

The obvious question with utilizing silicon as a fertilizer is why, with all of these positive effects, isn't it applied more as a nutrient? Raugewitz said the biggest hurdle regarding silicon remains educating people on the nutrient and the situations it is most useful.

Among the issues with silicon is the fact there are no current soil tests for gauging the amount of silicon for many agronomic or horticultural crops, she said. Also, there is a lack of analytical laboratories to test plant tissue for the nutrient.

In addition, Raugewitz said there is a lack of economic studies to show the benefits of applying silicon.

"Applying silicon and seeing an economic or agronomic benefit doesn't always happen at all times," Raugewitz said. "You might only see a change in times of extreme stress."

Despite these major challenges, silicon is gaining some footing as a nutrient in recent years.

Raugewitz said there has been a lot of research done in the last 30 years. Since 1999, when the first conference was held about silicon in agriculture, there have been at least five books, over 60 book chapters and numerous reviews and hundreds of refereed articles written about the subject.

Adaptation of using silicon as a nutrient has been highest in tropical regions, as well as rice-growing regions of the world, she said. The countries include India, China and Japan.

In the U.S., Florida and California lead the way in terms of applying the most silicon as a fertilizer, Raugewitz said. These states have many specialty crops on which the nutrient is applied, but commercial crops such as corn, soybeans, wheat and barley also all see a response when it is applied on them.

Russ Quinn can be reached at russ.quinn@dtn.com

Follow Russ Quinn on Twitter @RussQuinnDTN

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