Your Soil Day Guide: Four Things to Know About Ammonium Sulfate

Did you know that over 95 percent of our food comes from soil?  World Soil Day, held every December 5, reminds us of the vital role soil stewardship plays in feeding our communities worldwide. 

Healthy soils provide the essential nutrients plants need to grow, yet we deplete these nutrients with each harvest, so it is important to monitor their levels and supplement them as necessary.  All crops depend on adequate nitrogen and sulfur to build protein levels, to stay green and to grow. Sulf-N® ammonium sulfate (AMS) provides these essential nutrients in a form that plants can use right away, making it a dependable fertilizer choice for growers of any scale.  

To help mark World Soil Day, our in-house agronomist, Mercedes Gearhart, answers four common questions about ammonium sulfate.

What is the best time to apply sulfur? 

It depends on the crop. Small grains mostly benefit from sulfur fertilization early in the season to promote tiller formation, while canola is particularly sensitive at the time of flowering and seed set. With corn, nutrient uptake accelerates around the ten-leaf stage, so the soil needs to have enough available sulfur by then. For soybeans, having enough sulfur by the four-leaf stage is especially important because it supports good nodulation, which is how the plant produces its own nitrogen. 

How do different sulfur sources compare?    

In terms of the source, granulated elemental sulfur has a high sulfur concentration but breaks down very slowly, sometimes taking up to three seasons to become usable by plants. On the other hand, sulfate sources like Sulf-N® AMS are immediately available for plant uptake. On the heavier soils, a single application pre-plant or early in the season may be enough, whereas on sandy soils, split applications may be more efficient by reducing potential leaching losses in the event of heavy rainfall.     

Can I use ammonium sulfate in my vegetable garden? 

Certainly! Like grain and forage crops, vegetables also need nitrogen and sulfur for photosynthesis and protein formation. As a matter of fact, many industrial vegetable growers include ammonium sulfate as part of their basal fertilization blend. 

Does ammonium sulfate added to an herbicide mix improve weed control? 

Several herbicides recommend ammonium sulfate to enhance herbicide performance. Ammonium sulfate can be quite useful in situations of chemical antagonism, such as when using hard water or mixing herbicides that are antagonistic among themselves.  This use, however, may be specific to the herbicides you choose and may be subject to regulatory requirements, so it will be important to contact the herbicide manufacturer for clearance prior to use.   

Ammonium sulfate as an adjuvant can also be useful under stressful growing conditions, such as cold or droughty weather. Always refer to the corresponding herbicide label for specific rate recommendations. 

If you’re interested in learning more about how Sulf-N® AMS fertilizer can help your plants grow, take a look around our Plant Nutrients pages, starting here.

You can also submit your own question to Mercedes on our Ask the Agronomist page. 

Sources: 

1. https://www.fao.org/world-soil-day/en