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July 7, 2022

Can Elemental Sulphur Applications Benefit Subsequent Crops in a Rotation?

Combine Tractor in a field harvesting
Elemental Sulfur in Crop Rotation

With today’s high fertilizer prices, it’s natural for farmers to seek solutions that go farther in the field – and provide the required nutrients at the greatest possible value.

Applications of degradable elemental sulphur are shown not just to benefit the incoming crop, but also those that follow in the rotation. This is due to the slow and steady conversion of elemental sulphur into plant-available sulphate, estimated at 30-40% per year.

Results in an oilseed-cereal-legume rotation

A heavily cited study[1] involving researchers from the University of Saskatchewan and Tottori University (Japan) explored the effectiveness of elemental sulphur fertilizer in an oilseed-cereal-legume rotation.

The research team observed that many in the industry have looked at elemental sulphur from a limited perspective.

“Because of slow oxidation of elemental S (SO), research on SO fertilizers has emphasized improving the short-term availability, while the long-term effects of SO have been overlooked.”

Their three-year study compared three sulphur fertilizer applications: 00-00-00-95S dispersible elemental sulphur granule fertilizer; gypsum (CaSO4) and ammonium sulphate [(NH4)SO4]. The fertilizers were applied to the canola at 20, 40, and 80 kg S ha-1. Treatments were supplemented by corresponding rates of nitrogen. A control treatment was set up, with nitrogen only (no sulphur). Barley and peas followed in the rotation

They found in the first year, the canola yield was only slightly higher in the elemental sulphur fertilizer than the control. However, the following barley and pea crops saw superior yield results as the elemental sulphur oxidized.

Over the three-year rotation, the total crop S uptake was 21%, 4.0%, and 15% higher with the elemental sulphur than with the control treatment, gypsum, and AMS fertilizers, respectively.

Small sulphur particles critical

The research team in this study evaluated an elemental sulphur product that delivered an extremely fine particle size, less than 40 microns in diameter.

Particle size is key to agronomic performance. The finer the particle, the more surface area is available to the microbes responsible for oxidizing the sulphur into sulphate.

A top-performing degradable elemental sulphur fertilizer made with premium quality bentonite clay will maximize the breakdown of the pastilles. The better the clay, the greater the swelling and absorption of moisture to yield very small S particles, and higher agronomic performance.

Annual application improves early availability

This study showed that a one-time elemental sulfur application can have a residual effect on following crops in the rotation. Results can be further amplified by regularly applying elemental sulphur as part of an annual fertility management plan.

Additional research has shown that after 5 years of application, elemental sulphur levels can become self-sustaining. When soil sulphur levels and microbe population reach a critical point, the system can meet the crop’s immediate early-season sulphur needs.

Right crop. Right source.

Plants with a high sulphur demand, such as canola and peas – or crops grown in sulphur-deficient soils – will be most responsive to improving elemental sulphur levels in the soil.

If either situation applies to you, elemental sulphur is a long-term investment in your soil health. One that provides exceptional value for your nutrient dollar.

[1] “Effectiveness of an elemental sulfur fertilizer in an oilseed-cereal-legume rotation on the Canadian Prairies.” Wen, Schoneau, Mooleki et al. Journal of Plant Nutrition and Soil Science, Volume 166, 2003, p. 54-6

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