Sulfur (aka Sulphur or S) is known as “the fourth major plant nutrient”. While Nitrogen, Phosphorus, and Potassium are necessary for fertilized crops, Sulfur produces more nutritious foods and allows greater crop yields.
The fourth major plant nutrient works by conditioning the soil and reducing the soil’s sodium content. It’s often needed for soil that’s been regularly fertilized without adequate percolation.
Sulfur is also a component of some vitamins in plants. It helps plants form proteins, enzymes, vitamins, and chlorophyll. Sulfur also gives crops like onion, garlic, and mustard fuller flavors while helping legumes with nodule development and efficient nitrogen fixation.
Understanding the Fourth Major Plant Nutrient
With all the above being said, don’t just go ahead and add Sulfur to your soil and give it to your plants. Read through our list of the top 6 facts you need to know about Sulfur if you want to fully reap its benefits.
1. You Have to Determine the Crops You’re Growing and Your Yield Goal
Knowing what crops you're planning to grow and how much you plan to produce serves as the basis for other considerations down the line.
Needless to say:
Different crops require different amounts of nutrients to produce adequate yields. The amount of sulfur you'll need for a hectare of sunflower may be too much or not enough for a hectare of wheat. This is because certain crops, like alfalfa, are highly responsive to Sulfur and tend to take out more Sulfur from the soil.
2. You’ll Need a Soil and Plant Analysis
Another factor you have to consider is the amount of plant-available concentrations of plant nutrients (like Nitrogen, Phosphorus, Potassium, Sulfur, etc) in your soil. This can be determined through soil analysis.
Additionally:
You may also want to determine your soil's texture, organic matter content, and Sulfur contributions from other sources like manure and irrigation water. Soil with less than 2% organic matter will need more Sulfur, although sometimes even organic matter-rich soil can be Sulfur deficient.
Coarse textured soil (like sandy soil) will usually need more Sulfur than finer-textured soil (like clayey soil). However, even finer textured soils may be Sulfur deficient under certain circumstances. This is why a soil analysis is recommended.
Soil with more organic content will usually have higher Sulfur content.
On a similar note:
The irrigation water to be used may also deliver adequate amounts of Sulfur as your crops need. On the other hand, some places may have irrigation water that alkalizes your soil instead, which means you'll need to use more Sulfur.
Now:
Apart from soil analysis (and everything that comes with it), you'll also need a plant analysis. This process is a quantitative determination of elements in plant tissue.
3. Sulfur Lowers Soil pH
Despite Sulfur being an alkaline element to the human body, it actually makes the soil more acidic. This happens because of bacteria present in the soil. This soil bacteria converts Sulfur to sulfuric acid, thereby, decreasing soil pH.
It's this process that makes elemental sulfur one of the cheapest ways to make the soil more acidic. It should be noted, though, that since this is a biological process, rather than a chemical one, soil decreases pH more slowly and gradually.
Knowing this fact is crucial because:
4. Some Plants are Highly Sensitive to Changes in pH
Different species of plants prefer different soil pH levels. While changes in soil pH may not instantly kill them, they can significantly reduce your crop yield.
Here are some examples of plants and crops that prefer more acidic soil:
- Blueberry
- Blackberry
- Parsley
- Cranberry
- Raspberry
- Peanut
- Potato
- Sweet potato
- Azaleas
- Holly
- Dogwood
- Gardenia
- Magnolia
- Japanese iris
- Begonia
- Witch-alder
- Trillium
- Caladium
On the other hand, here are some plants and crops that prefer more alkaline soil:
- Asparagus
- Beet
- Brussels Sprouts
- Cauliflower
- Garlic
- Kale
- Sweet pea
- Deutzia 'Yuki Cherry Blossom'
- Caryopteris
- Clematis
- Forsythia
- Barberry
- Crocus
- Photinia
- Pole beans
- Lilac
- Silver Maple
- Buckeye
- Green Ash
- Hackberry
- Honey Locust
- Ironwood
- Austrian Pine
- Burr Oak
5. Buffered Soil May Be Too Costly Acidize
Plants usually prefer slightly acidic to neutral pH soil. A shift in soil pH also affects the microorganisms in that soil which in turn affects the soil nutrients.
If your soil is too acidic, you can "lime" it and make it more alkaline. "Liming" is the process of applying and working "lime" into your soil. This process is relatively straightforward.
The problem arises when your soil is too alkaline as is the case with calcareous soils which contain calcium carbonate (limestone) which is the same substance used to lime acidic soils.
If your soil contains solid lime deposits (buffered soil), it's basically impossible to permanently decrease your soil pH. We say “basically” because agronomists have found that it takes 68 tons of acid per acre to dissolve just 1% of CaCO3 in the upper 7 inches of soil.
So while you CAN technically acidize buffered soil, it would cost astronomical amounts of dollars to do so -- and that’s just for 1% of CaCO3 in the upper 7 inches of soil.
6. Sulfur Can Come From Many Sources
You can give your plants sulfur through manure and organic matter, pesticides, and fertilizers.
Sulfur through manure and organic matter won’t harm your plants. Any excess sulfur then gets absorbed by the soil as it becomes compost.
Seed oil crops usually get their sulfur from sulfur dusting and/or pesticides.
Sulfur contained in fertilizer can restore soil sulfur levels when used appropriately.
Pure Chem Co offers a product called Pure Sulfur Prills. This product comes at a 99.5% purity with no fillers or additives. Pure Sulfur Prills are tiny pellets of stabilized elemental sulfur made by melting sulfur into the water until it no longer fizzes.
Pure Sulfur Pellets can be used for your garden soil or hydroponic system. They are usually used in conjunction with a liquid plant nutrient solution, but a sulfur prill will still deliver nutrients without liquid fertilizer. You can start with 1 to 3 tbsp of sulfur prills depending on your plant's composition.
You can also use Pure Sulfur Prills to get rid of plant pests by mixing them with water and spraying the solution on your plants. This sulfur spray also acts as an effective fungicide and insecticidal spray.
Finally:
You can turn Pure Sulfur Prills into a fine dust by evaporating them in a sulfur burner should you wish to change the pH of leaf surfaces.
Note: If you're wondering where you can buy Sulfur Prills, you can visit our store and buy Pure Sulfur Prills with 99.5% purity, available in 2 lbs, 4 lbs, 8 lbs, 25 lbs, 50 lbs, and 100 lbs.