Phosphorus Application: Timing is Everything (Almost)

Website Editor • October 3, 2016

Wait!  How can this be?  Phosphorus is immobile.  We may lose a little phosphorus with our topsoil when we have extreme rain events but we won’t lose the applied phosphorus to volatilization and we won’t lose it to leaching.  If we are concerned about phosphorus availability can’t we just apply it in a band to prevent binding with cations in the soil and move on to more important things?  Traditionally, that is exactly what we have done:  Apply phosphorus prior to the crop season and move on – but there may be a better way! Let’s look at the way a crop uses phosphorus.  An article in Better Crops (2013) by Bender et, al. is very clear that a corn plant takes up phosphorus at a steady rate all the way until R6.  In fact they found that a corn plant takes up more than 75% of the phosphorus it uses after V10 (Figure 1).  If you are honest, you will have to admit the difference between when the crop is taking in phosphorus and when we are applying phosphorus simply don’t add up! Now let’s look at the likely-hood that traditionally applied phosphorus fertilizer is going to be utilized by the growing crop.  Research has shown that soil type and soil pH play a huge role in recovering phosphorus from fertilizer applications (Figure 2).  In soils with high clay content and high pH farmers may only be recovering 25% of the phosphorus fertilizer applied, meanwhile in very low pH soils aluminum may be binding even greater amounts of phosphorus! The good news is that evidence is beginning to support splitting phosphorus applications to gain greater efficiencies.  A recent NACHURS fertilizer study with Kansas State University yielded 32 more bushels (278 vs. 246) of corn by reducing preseason phosphorus application by 12 lbs of P205 and then applying the “saved” 12 lbs in season.   Likewise a recent Encirca field experiment in Texas yielded 24.5 bushels more corn by applying phosphorus with “Y drops” at V14 compared to nitrogen only applied at this time (112.7 bu vs 88.2).  These results really should not come as a surprise.  We have long seen the benefits from foliar applications of phosphorus.  These foliar applications are simply another way of moving phosphorus into crops in a more efficient manner.  We are witnessing a great number of advances in crop production fertility systems.  Old thought processes would have farmers believe that since phosphorus is relatively immobile it may be applied at any time during the year.  However, new discoveries may change that perception.  New chemistries and new practices will help reduce environmental impact and improve production and profitability.   Figure 1: Total maize P uptake and partitioning across four plant stover fractions and grain tissues.Figure 2:  Fixen, P.E., and A.D. Halvorson. 1992. Land tenure effects on phosphorus management. - Wayne Becker, US South Regional Sales Manager

Wait!  How can this be?  Phosphorus is immobile.  We may lose a little phosphorus with our topsoil when we have extreme rain events but we won’t lose the applied phosphorus to volatilization and we won’t lose it to leaching.  If we are concerned about phosphorus availability can’t we just apply it in a band to prevent binding with cations in the soil and move on to more important things?  Traditionally, that is exactly what we have done:  Apply phosphorus prior to the crop season and move on – but there may be a better way!

Let’s look at the way a crop uses phosphorus.  An article in Better Crops (2013) by Bender et, al. is very clear that a corn plant takes up phosphorus at a steady rate all the way until R6.  In fact they found that a corn plant takes up more than 75% of the phosphorus it uses after V10 (Figure 1).  If you are honest, you will have to admit the difference between when the crop is taking in phosphorus and when we are applying phosphorus simply don’t add up!

Now let’s look at the likely-hood that traditionally applied phosphorus fertilizer is going to be utilized by the growing crop.  Research has shown that soil type and soil pH play a huge role in recovering phosphorus from fertilizer applications (Figure 2).  In soils with high clay content and high pH farmers may only be recovering 25% of the phosphorus fertilizer applied, meanwhile in very low pH soils aluminum may be binding even greater amounts of phosphorus!

The good news is that evidence is beginning to support splitting phosphorus applications to gain greater efficiencies.  A recent NACHURS fertilizer study with Kansas State University yielded 32 more bushels (278 vs. 246) of corn by reducing preseason phosphorus application by 12 lbs of P205 and then applying the “saved” 12 lbs in season.   Likewise a recent Encirca field experiment in Texas yielded 24.5 bushels more corn by applying phosphorus with “Y drops” at V14 compared to nitrogen only applied at this time (112.7 bu vs 88.2).  These results really should not come as a surprise.  We have long seen the benefits from foliar applications of phosphorus.  These foliar applications are simply another way of moving phosphorus into crops in a more efficient manner. 

- Wayne Becker, US South Regional Sales Manager

March 17, 2025
Transform Your Harvest: Discover the Benefits of Finish Line®
March 13, 2025
The effect of foliar fertilization on wheat yield.
December 12, 2024
We are at the point in the year where things are slowing down around the farm and it is time to reflect on the season to remind ourselves what we learned. Over the last couple of weeks, the District Sales Managers and I have spent some time reflecting on what worked well in the field and the challenges we faced too. Here are the top 5 things we learned from 2024 growing season: #1 Split applying Nitrogen and Sulfur is a practice that should be embraced on a yearly basis when growing corn. Do you remember how the planting season started and what happened in the first 60 days after the planters started rolling? Our field conditions started out dry with some areas of the corn belt showing up on the drought map. Then mother nature blessed us with rain that never stopped in some areas making it difficult to finish planting. Growers that had split applied their Nitrogen and Sulfur were able to avoid nutrient loss from the rain but also apply the nutrients when the crop needed it most. In the end yield was better on split applied nitrogen fields compared to fields that had all the N applied in the fall or spring before planting. #2 For the past 2 seasons in the North region, we have seen the benefits of adding NACHURS Humi-Flex FA to the in-furrow starter fertilizer. NACHURS Humi-Flex FA is our fulvic acid and it is becoming a valuable component in our starter fertilizer for many reasons. We are using it to chelate the nutrients in the starter fertilizer especially phosphorus. Humi-Flex FA also buffers the soil pH to neutral in that nutrient band keeping nutrients available in fields that have less then optimal pH for crop growth. Finally, we use Humi-Flex FA to create a healthy soil microbiome that leads to more root mass and nutrient uptake. #3 Nutrient uptake charts for corn and soybeans have been a great tool for our team to help our customers visualize the crops nutrient needs based on timing during the growing season.
November 21, 2024
The importance of Phosphorus
August 27, 2024
Fungicide applications: the determining factors to be considered
August 20, 2024
Strategic Applied Fertilizer: Reallocation
July 30, 2024
The right nutrient source
More Posts