Understanding and Managing Sulfur (S) Deficiency

Sulfur—the unsung hero of crop nutrition. In this article, we delve into the impact of sulfur deficiency on crop yields. We’ll examine its effects on various crops, pinpoint common signs of deficiency, explore proactive measures to avert deficiencies, and detail remediation strategies.

What is a sulfur deficiency?

A sulfur deficiency refers to inadequate sulfur in the soil or insufficient absorption by plants. This deficiency can result in various physiological issues, such as poor growth, chlorosis (yellowing), and decreased yield. Additionally, sulfur deficiency may compromise the plant’s ability to resist pests and diseases, ultimately impacting overall crop quality.

Why is sulfur so important for crops?

Although it may not be one of the big three (nitrogen, phosphorus, or potassium), sulfur is a limiting factor in crop yield and quality! Sulfur is essential for crops, contributing to protein synthesis, enzyme activation, and chlorophyll formation. It is also crucial for plant growth and photosynthesis. Sulfur aids in stress response, disease resistance, and vitamin synthesis, ensuring healthy plant development and high-quality crop yields.

How does sulfur deficiency affect specific crops?

Sulfur affects different crops in different ways, but the takeaway is that deficiencies can impact quality, growth, and market value.

Crop-Specific Effects of Sulfur Deficiency:
• Potatoes: Sulfur deficiency in potatoes can lead to reduced dry matter accumulation. This diminishes tuber quality and marketability, affecting potato growers’ profitability.
• Soybeans: Soybeans are highly sensitive to sulfur deficiency due to the interaction of nitrogen and sulfur, and the importance of nitrogen fixation for a healthy and productive soybean crop. Additionally, reduced sulfur levels may lead to decreased seed quality and protein content, impacting soybean yields and profitability.
• Corn: Corn plants experiencing sulfur deficiency may exhibit symptoms such as foliar chlorosis and reduced kernel development. This can ultimately lead to lower grain quality and yield, affecting corn producers’ bottom line.
• Cotton: Sulfur deficiency can adversely affect cotton plants, such as increasing the risk of leaf curl and boll rot. This can lead to decreased fiber quality and yield, affecting cotton producers’ ability to meet market demands.
• Apples: Apple trees affected by sulfur deficiency may have reduced growth and foliar chlorosis These issues diminish fruit quality and shelf life, impacting apple growers’ profitability and marketability.
• Canola: Sulfur deficiency in canola can impair protein and oil production, leading to reduced yield, poorer seed quality, and increased susceptibility to pests and diseases. Proper sulfur fertilization is crucial for optimizing canola growth and maximizing crop productivity.

Doesn’t soil in the US have enough sulfur?

Historically, sulfur deficiency wasn’t a significant worry for growers because organic matter and sulfur emissions provided ample crop supply. However, over the last three decades, reduced sulfur emissions have significantly diminished the availability of atmospheric sulfur in North America. Additionally, increased crop productivity means greater uptake and removal of sulfur during harvest. As a result, both visible and hidden sulfur deficiencies are becoming more widespread in many regions.

What are the common signs and symptoms of sulfur deficiency?

Signs of sulfur deficiency can vary depending on the severity and the specific crop but may include common symptoms such as:

• Yellowing of leaves (chlorosis): Sulfur deficiency often causes the younger leaves to turn yellow, starting at the tips and edges and progressing inward. This symptom can appear similar to a nitrogen deficiency. It typically begins at the tips and edges of the leaves and can progress inward. In severe cases, the entire leaf may turn yellow.
• Stunted growth: Insufficient sulfur can lead to stunted plant growth, as sulfur is necessary for cell division and overall plant development. Stunted plants may appear smaller and less vigorous than healthy plants.
• Delayed maturity: Plants deficient in sulfur may take longer to mature and produce fruits or seeds than healthy plants.
• Reduced Nutrient Uptake: Sulphur deficiency can interfere with the plant’s ability to take up other essential nutrients like nitrogen, leading to imbalances in nutrient levels.

How does sulfur deficiency impact yield?

Sulfur deficiency lowers crop yields and quality by impairing the formation of crucial compounds like proteins and oils. It also makes crops easier targets for pests and diseases, weakening plants’ defense mechanisms. The bottom line? Keeping those sulfur levels in check is key to ensuring healthy crops and maximizing productivity.

How can growers avoid sulfur deficiency?

• Soil testing: Regular soil testing can help farmers monitor sulfur levels in the soil and adjust fertilizer applications accordingly.
• Sulfur fertilization: If soil tests indicate low sulfur levels, sulfur-based fertilizers can be applied to correct the deficiency. Applying multi-nutrient gradual-release sulfur, such as Polysulphate, instead of more rapid-releasing sulfur fertilizers like ammonium sulfate, potassium sulfate, or very slow-release elemental sulfur that is also dependent on microbial breakdown can help. Likewise, controlled-release fertilizers like Agrocote and water-soluble fertilizers like Nova SOP can mitigate deficiencies depending on the farming operation and application preference. These should be applied according to recommended rates and timing.
• Crop rotation: Some plants are more sensitive to sulfur deficiency than others. Rotating crops can help prevent sulfur depletion in the soil, as different crops have varying sulfur requirements and uptake rates.
• Organic matter addition: Incorporating organic matter such as compost or manure into the soil can gradually increase sulfur levels over time.
• pH management: Soil pH can affect sulfur availability. Maintaining optimal soil pH levels (typically around neutral to slightly acidic) is essential for ensuring adequate sulfur availability for plant uptake. Soil amendments or acidifying fertilizers, like Nova PeKacid or Agrolution pHLow, may be required to adjust pH levels and optimize sulfur availability in agricultural soils.

Why is Polysulphate (polyhalite) an excellent source of sulfur?

• Multiple Nutrients: Polysulphate contains sulfur and other essential nutrients, such as low-chloride potassium, magnesium, and calcium. This makes it a well-balanced fertilizer that can meet various crop nutrient needs with one granule.
• Plant-Available, Gradual Release: This provides plants with a sustained supply of sulfur. Sulfur is available during crucial growth stages like rapid vegetative growth and reproductive development. The gradual release pattern also helps prevent nutrient leaching and ensures crops can access sulfur and other nutrients when needed.
• Low Salt Index: Polysulphate has a low salt index compared to other fertilizers, making it safe and suitable for use on sensitive crops.
• Environmental Benefits: Polysulphate is a naturally occurring mineral fertilizer mined from underground deposits. Its production typically involves minimal processing, resulting in lower energy consumption, greenhouse gas emissions, and a low carbon footprint compared to synthetic fertilizers. Plus, it’s OMRI-approved.

Sulfur management is important to maximize crop yield and prevent imbalanced nutrition. It’s crucial to monitor soil nutrient levels and follow recommended guidelines for sulfur application. Remember, our agronomists and team of product experts are here to help!