Is Phosphorus depleted in our food?

I recently read a book on Nutrition & Public Health written in the 1940s. 
A major concern then was the stripping of phosphorus from the soil and the effect the continued depletion would have on human health.

To illustrate this point in 1937 Franklin D Roosevelt famously said:
“The Nation that destroys its soil destroys itself.”

Reflecting a wider fear at the time that:
1) Continuous cropping was stripping soils of essential minerals like phosphorus
2) Food quality (and therefore public health) would decline
3) The U.S. could face long-term agricultural collapse

Fast forward to 2026 and phosphorus is one mineral we don’t have to worry about as depleted in our soils. 
So what has changed?

Back in the 1930s–40s, concern about phosphorus depletion was not misplaced. Phosphorus is essential for plant growth (and therefore for human nutrition), but unlike nitrogen, it doesn’t have a natural cycle.

Once it’s removed from soil through crops, it has to be replaced or it has gone. Back then there was no mechanism to replace it.

Why the turn around from scarcity to plenty?
1. Industrial fertilizer revolution
The biggest factor was the large-scale mining and use of phosphate rock.
a) Huge phosphate deposits were developed in the late 19th century in places like Florida, Morocco, and China

b) These are processed into phosphate fertilizers and spread back onto fields
This essentially “short-circuited” the natural depletion problem by importing phosphorus onto farmland.

2. The Green Revolution
From the mid-20th century onward, the Green Revolution dramatically increased yields through:
a) Synthetic fertilizers (including phosphorus)
b) High-yield crop varieties
c) Irrigation and mechanization

This made it possible to maintain (or even increase) soil phosphorus levels.

3. Recycling improvements
Some phosphorus is now recycled through:
* Animal manure
* Sewage sludge (biosolids)
* Food waste (to a lesser extent)
However, this recycling is still inefficient, much phosphorus is lost to waterways - making phosphorus a different kind of problem.

4. Shift in the problem (depletion to pollution)
Ironically, the concern didn’t disappear it has flipped
Today, the bigger issue is excess phosphorus in many regions.
Runoff into rivers and lakes causes eutrophication (algal blooms, dead zones) Famous cases include problems in lakes like Lake Erie.

So instead of “not enough phosphorus,” now we often have “too much in the wrong place.”

But is phosphorus really no longer a concern?
Not quite. The anxiety has shifted from soil depletion to long-term supply risk:
a) Phosphate rock is a finite resource
b) Reserves are geopolitically concentrated (especially in Morocco)

Have we have reached “peak phosphorus”?

So the 1940s concern hasn’t vanished—it’s just been postponed and transformed by industrial agriculture.

Anyway - at least we don’t need to worry about whether we are getting sufficient phosphorus in our diet - for the moment.

References

The American Presidency Project (University of California, Santa Barbara).

 

MAHB (Stanford): Discussion of the quote and soil management urgency.

 

American Society of Agronomy: “The history of the United States phosphate fertilizer industry.”

 

Alliance of Bioversity International & CIAT: Overview of synthetic fertilizers' role.