Experts Answer Top Questions on Smarter Phosphorus Management

Despite the importance of phosphorus in many vital plant processes, the behind-the-scenes contributions of phosphorus tend to be overlooked. To provide insights on the complexities of phosphorus management, three Koch Agronomic Services experts — Tim Laatsch, director of agronomy, North America, TJ Bingham, technical agronomist and Ryan Bond, vice president of innovation and business development — share their expertise on:

• The differences between organic and inorganic phosphorus
• The value of phosphorus throughout the season
• How growers can unlock phosphorus already present in the soil

Why is phosphorus availability a challenge for growers?

Laatsch: The biggest challenge growers face isn’t necessarily a lack of phosphorus in the soil — it’s making sure phosphorus is available when crops need it. A lot of applied phosphorus quickly becomes tied up due to soil conditions, leaving plants unable to access the nutrients they require. It’s a widespread problem across different soil types and regions.

Bingham: The reality is that most soils have plenty of phosphorus — it’s just not in a plant-available form. Traditional fertilizers often fail to solve this problem because the phosphorus they provide can also quickly become chemically bound. That’s why phosphorus efficiency is such a critical issue for growers.

What’s the difference between inorganic and organic phosphorus in the soil?

Bingham: Growers are used to thinking about phosphorus in terms of fertilizer, but there are actually two different pools — organic and inorganic. Most people focus on the inorganic side, but the organic phosphorus pool has been largely untapped. Each source requires different tools to make phosphorus available to crops.

Bond: It’s important to distinguish between the two pools — the inorganic phosphorus pool consists of plant-available forms like orthophosphate, but this pool is small and can be depleted quickly. Meanwhile, the organic phosphorus pool is much larger but locked up in plant residues and microbial biomass. Until now, we haven’t had a good way to consistently tap into that pool and make it available to crops.

If growers see phosphorus deficiency symptoms in their crops, is it too late to correct the issue?

Laatsch:  Once you see purpling of leaves or stunted growth, the crop is already experiencing a significant phosphorus deficiency. At that point, yield potential has likely been compromised. But even before visible symptoms appear, low phosphorus levels can silently impact productivity through what we call ‘hidden hunger.’ This occurs when nutrient levels are below sufficiency for optimal yield, even though the plant may not show clear deficiency symptoms yet.

Bingham: Phosphorus management has to be proactive, not reactive. Unlike nitrogen, where you can sometimes apply a rescue treatment mid-season, phosphorus deficiencies are much harder to correct after the fact. That’s why it’s so important to improve phosphorus availability in the soil from the start.

Why doesn’t phosphorus get as much attention as nitrogen in nutrient management?

Laatsch: Nitrogen tends to get most of the credit for driving plant growth because its effects are more immediate and visible. When you apply nitrogen, you see a quick response in plant color and vigor. Phosphorus, on the other hand, is just as critical, but its impact is more subtle. It’s working behind the scenes to support root growth, energy transfer and grain development. If phosphorus is deficient, you may not notice right away, but it can limit crop performance.

Bond: Nitrogen is the star of the show when it comes to fertility discussions. Phosphorus is needed for energy production (ATP synthesis) and nutrient transport, meaning that even if you have plenty of nitrogen, the plant still requires phosphorus to use it efficiently.

Planning ahead: What should growers consider when applying phosphorus? 

Bingham: Phosphorus doesn’t move easily through the soil, so placement is key. Banding phosphorus near the root zone improves uptake, and split applications can help ensure availability during peak demand periods. But even with the right placement and timing, phosphorus availability is still influenced by soil chemistry, microbial activity and environmental conditions.

Bond: Another consideration is the longevity of phosphorus availability. Many early-season phosphorus applications are quickly tied up in the soil, meaning they may not be available for mid- and late-season growth. Growers need to think about how they can extend phosphorus availability beyond those first few weeks. One way to approach this is by following the 4Rs of nutrient stewardship — applying the right source of phosphorus at the right rate, the right time and in the right place to improve efficiency and minimize loss.

How can growers improve phosphorus availability throughout the season?

Laatsch: Traditionally, growers have had two options: apply more phosphorus fertilizer or hope that enough gets released from the soil at the right time. But neither of these approaches is particularly efficient. The challenge is finding a way to make phosphorus consistently available throughout the season without over-applying fertilizer.

Bingham: We know that phosphorus tie-up happens quickly, so relying on a single fertilizer application often isn’t enough. New technologies are helping bridge this gap by improving phosphorus efficiency and making more of the phosphorus already in the soil available to crops.

Phosphorus beyond early-season: Why ongoing availability matters.

Laatsch: Phosphorus is often thought of as an early-season only nutrient, but it plays a key role throughout the growing season, including mid-season reproductive stages. In crops like corn, by the time the plant reaches VT, it’s shifting from vegetative to reproduction, and phosphorus supports this transition. A shortage at this stage can impact pollination and seed development, ultimately reducing yield. 

Bingham: Mid-season is when many crops are rapidly taking up nutrients, and phosphorus availability at this stage helps sustain plant energy levels and support reproductive success. If phosphorus is limited, it can lead to poor seed set, lower grain fill and diminished quality — issues that can’t be reversed later in the season.

Bond: Many crops require a steady phosphorus supply well beyond early growth stages. Growers often apply phosphorus with starter fertilizers and think the job is done. But the plant’s demand doesn’t stop after early growth. Phosphorus availability through mid-season ensures that crops have the energy they need for steady growth and to develop strong yields.

What role does enzyme technology play in phosphorus management?

Bond: Enzyme technology is changing the way we think about phosphorus availability. Instead of just adding more phosphorus, we’re now able to unlock what’s already there in the soil. By targeting the organic phosphorus pool, enzymes provide a more efficient, sustainable way to improve phosphorus uptake.

Bingham: What makes enzyme technology unique is that it’s not dependent on a living organism to function. Unlike microbial products that require the right soil conditions to work effectively, enzymes start working immediately and provide a more predictable and consistent response.

How does PHOSFORCE™ fit into a smarter phosphorus management strategy?

Laatsch: PHOSFORCE™ is designed to work with a grower’s existing fertility program by targeting the organic phosphorus pool. It accelerates phosphorus mineralization, making it available to plants up to 8 weeks rather than just a short window after application.

Bond: It is really about taking a more strategic approach to phosphorus management. PHOSFORCE helps bridge the gap between early-season phosphorus applications and the later growth stages when crops still need phosphorus for energy production, seed development and grain fill.

Taking phosphorus management to the next level. 

Managing phosphorus effectively requires more than just applying fertilizer. By understanding phosphorus dynamics in the soil and leveraging enzyme technology, growers can optimize phosphorus availability, improve plant and soil health and maximize yield potential.

To learn more about PHOSFORCE and how it fits into a smarter phosphorus management strategy, visit https://kochagronomicservices.com/phosforce.