Apr 5, 2021

Sulfur: for a healthy crop, tasty and high-yielding

{Sponsored} Sulfur’s one of the most widely used and well-known products in American agriculture. In use as a fertilizer and a pesticide for more than 100 years, is there still a role for it in an age of newer, more modern crop inputs?

 Don’t let anyone tell you sulfur’s had its day, says Mike Williams, CEO of crop nutrition specialists OMEX® Agrifluids USA. This vital, basic element needs to be seen in the same light as nitrogen, phosphorus and potassium; if you’re focused only on NPK then you’re holding back your crop.

Why is sulfur so important?

As the ‘fourth macronutrient’, sulfur’s role in crop biochemistry can’t be ignored. Of similar importance to nitrogen or phosphorus, it supports plant functions that can affect yield, quality and marketability.

All plants demand adequate sulfur levels for nitrogen uptake, chlorophyll production, root development, stress and pest resistance, carbohydrate generation, amino acid formation and vitamin synthesis. Decreased efficiency in any area becomes a limiting factor on crop yield and potential, while it also plays a significant role in how crops taste and smell, and how they perform in subsequent use.

For example, the all-important gluten in wheat — giving bread its chewy, soft texture — depends on sulfur-sulfur bonds. Good breadmaking wheat needs good sulfur. Sulfur also forms ‘volatile sulfur compounds’: essential for the juicy, fresh aromas we associate with perfectly ripe, flavorsome strawberries, apples, pears and other fruits.

What makes sulfur management tricky is that, across all crops, sulfur deficiencies rarely present with visible symptoms. Hidden deficiency is often more damaging than acute deficiency, as it’s usually only discovered when it’s too late to remedy.

But sulfur also has another role, as a fungicide. Indeed, sulfur-based fungicides were amongst the first available to farmers and they remain important today.

How to manage sulfur

It’s important to understand how plants absorb sulfur. Their preference is for sulfates: it is the only form in which plant roots can access the nutrient. There’s a limited role for leaves: not only can they absorb small quantities of sulfur dioxide direct from the atmosphere, they also help to regulate nutrient absorption while combating disease.

When applied as a foliar spray, the nutrients slowly enter the plant tissue as required. But when present on the leaf surface, sulfur’s disease-suppressing abilities act in synergy with later applications of fungicides or insecticides. This means a healthy plant can stave off infections itself, putting less strain on modern fungicides within the program and reducing the risk of resistance development.

In this respect, sulfur is a tremendously versatile workhorse to have within the fruit grower’s plant protection armory. It’s no coincidence that the incidence of diseases such as powdery mildew increases when there’s even moderate sulfur deficiency. Yet during the growing season, a crop’s sulfur requirements can often greatly exceed the soil’s inherent capacity to supply it, particularly as levels are now in decline.

While no-one would decry the Clean Air Act, the huge reduction in power plant emissions has brought about a massive decrease in atmospheric sulfur: EPA data shows sulfur emissions fell 94 percent between 1990 and 2019. That means farmers must now make up for the sulfur products they previously enjoyed ‘for free’.

Choosing the right product is important. At OMEX®, our focus is on products that are immediately bioavailable, either because they’re unaffected by soil microbial activity or because they take advantage of specific plant characteristics.

OMEX® SulphOMEX® Ultra® is our ‘take’ on sulfur. Its special co-formulation of sulphate and nitrate allows immediate use by the plant of the form of nitrogen most readily absorbed by plant roots, while delivering a solution of very fine sulfur particles that can reach the most difficult target sites of the plant. That’s in contrast to conventional formulations of micronized sulfur, which are notoriously difficult to apply.

This formulation also reduces sulfur’s propensity for phytotoxicity, even during sensitive flowering stages. And although it contains multiple sulfur sources, it’s not registered as a fungicide, but as a fertilizer — reflecting the importance of sulfur we’ve already described.

As for sulfur ‘philosophy’, i.e. application, it’s best to take the little and often approach. This way, you’ll not only reduce leaching — environmentally unsound but also representing an immediate loss to your bottom line — but maintain sulfur at sufficient levels both in the soil and on the leaf, such that it’s always available to the plant during periods of rapid growth. In this way, lack of sulfur is never going to become a limiting factor in your pursuit of optimizing yield potential!

Consult your agronomist or adviser for the rate of SulphOMEX® Ultra that’s right for your crop. Between 1 and 3 ½ pints per acre, integrated into early season insecticide and fungicide sprays, will not only build sulfur content within the plant, but also provide the crop with an additional mode of suppressive action that can build the foundation for a healthy, high-yielding and disease-free crop — and one that’s packed full of those flavorsome sulfur compounds that give fruit its appeal.

Learn more at www.OMEXusa.com.

The product names and brands referenced here are registered and trademarks of OMEX® Agrifluids, Inc.

© OMEX® Agrifluids, Inc. 2021.