Dry Fertilizer

Focus dry fertilizer dollars only in areas below the critical levels that are likely to provide a positive return

STEP 2
  1. Dry fertilizer rarely increases yield... why?  LEARN MORE
  2. Probability and magnitude of yield response to dry fertilizer. LEARN MORE
  3. When does applying dry fertilizer lead to profit?  LEARN MORE

1) It rarely comes in contact with it!

Diagram comparing fertilizer application methods: broadcast spread vs. precision placed.
  •   Roots explore ~ 1-2% of total soil volume. 
  •   Broadcast nutrients are diluted across millions of cubic inches of soil
  •   Phosphorus is immobile.
  •   Potassium moves slowly.


If nutrients aren’t placed where the roots are growing, efficiency drops dramatically. 

2) A hidden salt load problem exists

Every pound of fertilizer added to the field adds DISSOLVED SALTS to the soil solution. Broadcasting salt across 43,560 square feet does not guarantee roots will find nutrients – but it does guarantee the entire field carries the osmotic load, reducing the plant’s ability to absorb water.

UNDERSTANDING THE SALT INDEX


The Salt Index (SI) isn’t a true physical unit like pounds or gallons. It’s a relative measurement of “osmotic effect”, how hard that fertilizer makes it for plants to pull in water. Originally developed by Rader et al. (1943), the Salt Index (SI) measures the relative increase in osmotic pressure caused by a fertilizer compared to sodium nitrate. 


Ex: If the SI = 50, it creates half of the osmotic effect of sodium nitrate. 

2) Varying by state, most soil test sent to labs are above the critical level with a low likelihood of a positive return to dry fertilizer.

Regional Soil Nutrient Deficiency Overview

KEY TAKEAWAY

This data is utilizing Bray P1 extraction for phosphorus and ammonium acetate for potassium. The critical levels vary

by state due to multiple factors including the crops grown in that state.



Michigan appears to have 66% of the samples below the critical level for K. However, they are basing that off of a

critical level of 150 ppm, not 120 ppm. We have included this information to simply be a point of reference. In making actual recommendations, we would like to look at your actual soil tests as they will vary from farmer to farmer.

What are the critical levels?

The critical level is defined as being deficient for optimal crop growth with yield losses likely to occur.

Probability and magnitude of yield response to dry fertilizer

Soil Phosphorus and Crop Response to Phosphorus Fertilizer in Ohio, Culman et al. (2023) 457 TRIALS – 45 YEARS – 40 OHIO COUNTIES – on farms and research stations.  RESEARCH WAS CONDUCTED ON CORN, SOYBEANS AND WHEAT.

DID YOU KNOW?

Soil testing is a wise investment! It helps identify where dry fertilizer is likely to pay. When is that likely to be profitable?

See the Data Above!

The Average removal rate of dry fertilizer requires roughly 11 bushels of corn and 4 bushels of soybeans just to pay for the fertilizer.


Refer to tables 1 & 2 above to determine the likelihood of paying back.

11 Bushels of Corn

4 Bushels of SOYBEANS

WHEN DOES APPLYING DRY FERTILIZER LEAD TO PROFIT? 

WHEN SOIL TEST LEVELS ARE BELOW CRITICAL LEVELS, DRY FERTILIZER ABSOLUTELY CAN INCREASE YIELDS. ABOVE CRITICAL LEVELS, ADDED BROADCAST NUTRIENTS OFTEN INCREASE SOIL SALT LOAD MORE THAN PLANT PERFORMANCE. 


It is not about how many pounds you apply. It’s about how many pounds the plant actually touches and takes up – without creating unnecessary salt stress in the process.