Starter Fertilizer For Corn: 5 Things To Know

Is Starter Fertilizer Right for Your Cropping System? Five Tips for Maximizing Its Benefits

While many farmers are reducing their use of starter fertilizer, the practice still garners attention due to its potential to boost early crop growth. However, whether it delivers an economic benefit is not always certain. Before deciding whether starter fertilizer is right for your operation, consider these five key tips to help determine if the practice will truly enhance your yield.

1. Understand the Role of Starter Fertilizer

Research does not universally support the widespread use of starter fertilizers across all regions. While starter fertilizers can promote early growth, the yield benefit does not always follow. According to experts, the most noticeable effect of starter fertilizers is the boost to early plant development. However, this early growth can often be cosmetic—improving the appearance of crops without translating into higher yields. The primary advantage of in-furrow application lies in its ability to enhance nutrient uptake, particularly nitrogen and phosphorus, during the early season when these nutrients may be limited.

For growers using reduced tillage systems, starter fertilizer may have a greater benefit, as the cooler, wetter soils can hinder nutrient availability. In these cases, in-furrow starter fertilizer can help crops access key nutrients during this critical early growth phase.

2. Consider Placement Options for Nutrient Efficiency

The effectiveness of starter fertilizer depends largely on where and how it is applied. The placement strategy should align with the nutrient being applied. Immobile nutrients such as phosphorus, potassium, and micronutrients like zinc are most effective when placed close to the plant’s root zone. However, nitrogen and sulfur, which are more mobile in the soil, can be detrimental to seedling germination if placed too near the seed.

For continuous corn systems, research has shown that banding nitrogen and sulfur on the soil surface, to the side of the seed row, can improve yield. This method can also benefit crops following soybeans, especially in poorly drained soils. However, it's important to note that excessive starter fertilizer can cause stand damage. To mitigate this risk, growers should ensure at least one inch of soil separates the seed from the starter fertilizer band.

3. Select the Right Fertilizer Source for Your Needs

The type of liquid fertilizer you choose as a starter is crucial for achieving desired results. Corn yield, for example, is often limited by the nutrient that is in the shortest supply. Selecting a starter fertilizer that targets these nutrient deficiencies is essential. For growers looking to promote early growth, a starter with high phosphorus pentoxide content is recommended. These starters can economically apply around 10 pounds of phosphorus pentoxide per acre in-furrow, which is beneficial for early growth, hastens crop dry down, and may potentially increase yields.

In high-residue systems, a combination of nitrogen and sulfur, such as 28% or 32% UAN (urea-ammonium nitrate) with ammonium thiosulfate, may be more appropriate. These nutrient combinations are particularly effective when banded on the soil surface to improve nutrient availability.

4. Ortho- vs Poly-Phosphate: What’s the Best Choice?
The debate between using 100% ortho-phosphate starter fertilizer and poly-phosphate alternatives often comes down to cost. While it’s true that plants do not directly take up polyphosphate, products like 10-34-0 contain both ortho- and polyphosphate. Although polyphosphate must convert to ortho-phosphate before being available to plants, this conversion happens quickly in most soils.

The benefit of higher-cost ortho-phosphate products may be more evident if potassium is also required, but for most growers, 10-34-0 remains a viable and cost-effective option. When comparing products, farmers should calculate the cost per unit of nutrient applied to ensure they are getting the best value. 10-34-0 often offers the best concentration of phosphorus pentoxide at a lower cost than alternatives.

5. Determine the Right Application Rate
Determining the correct application rate for starter fertilizer depends on the placement method and the specific nutrients being applied. Fertilizer calculators can assist in selecting the appropriate rate, but it’s essential to keep in-furrow starter fertilizer rates as low as necessary to achieve the desired effect. Soil moisture levels can influence fertilizer uptake, so adjustments may be needed based on field conditions.

When applying starter fertilizer as a sub-surface band or to the side of the row, growers may have more flexibility with higher rates, as the fertilizer is further from the seed. Additionally, applications should be considered supplementary to other fertilizer sources, such as manure or dry fertilizers.

Test the Practice to See if It Pays Off
Ultimately, the decision to use starter fertilizer should be based on whether it improves yield or reduces other production costs. While starter fertilizer can potentially enhance early growth and reduce drying costs, it is not guaranteed to provide an economic return. One way to assess its effectiveness is by skipping starter fertilizer for a few passes and comparing the results. If starter fertilizer improves performance, then it may be worth reintroducing; otherwise, growers should focus on alternative methods to ensure they are maximizing profitability.