Planter Sulfur Applications

By Tim Duckert, Research Agronomist, North Central Research Station

Happily, crop yields have increased exponentially over the last 20 years. However, these high yield goals require a larger supply of nutrients, including sulfur. Due to the increased need for sulfur (S), the reduced supply of atmospheric sulfur, and losses to the environment, it’s necessary to include sulfur as a consideration in all crop nutrition plans.

Just a Reminder: S Is Important

As with many crop nutrients, sulfur plays a part in many plant functions. One of the primary reasons sulfur is critical to crop production is that it works hand-in-hand with nitrogen in the plant. Sulfur is required to allow the plant to use nitrogen efficiently. Poor nitrogen performance in crops is often associated with lower than optimum available sulfur. But sulfur is a vital crop nutrient itself. It is an integral part of amino acids, which are essential for plant protein production. It also contributes to chlorophyll formation which is a key component of photosynthesis in plants. Considering what we know of the need for sulfur, and taking into account cooler environmental conditions at planting which may limit any mineralization of sulfur from the soil, we can extrapolate that early sulfur applications may be beneficial to the development of the young seedling.

Especially at Planting

There are many different application methods and products available to meet the sulfur need of today’s crops. Applying sulfur with the planter is an excellent placement method to get the available form of the nutrient next to the root system and maximize the benefit to the new plant. This placement can also be more environmentally friendly because it is placed near the zone of uptake and will likely get used by the young plant before it has a chance to leach from the soil system.

What S Fertilizer Can Be Used In-Furrow?

One of the best products to apply with the planter is AgroLiquid’s eNhance™, which can be safely  applied in furrow with common rates of 1-2 qts/A for most crops. It has been an exceptional product for providing three to six pounds of equivalent sulfur at those rates. Very few—if any—other sulfur products can be used in-furrow. This gives eNhance an edge, when applied infurrow, of being the closest sulfur source to the new seedling’s root system.

Applying nitrogen while planting also provides an opportunity to add sulfur to the nutrient program. The addition of sulfur to applied nitrogen improves the plant’s response to that nitrogen. One AgroLiquid product that mixes well with liquid nitrogen fertilizers is accesS. Nitrogen fertilizer is often placed 2×2 or on one or both sides of the row, the latter of which is becoming more common. These placement areas near but not directly with the seed are still beneficial to the young root system. AccesS should only be applied away from the seed and the aforementioned systems work well for planter application of this product. A typical planter application may be 1-2 gallons per acre which would provide five to 10 pounds of equivalent sulfur.

But What Does the Data Show?

The chart below shows data from both eNhance and accesS in multi-year studies. At least seven years of data and 12 experiments were used to compare additional planter applied sulfur to a normal planter program without sulfur.