The Inverse Relationship Between Soil Fertility and Your Credit Line

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About this time every year, the people in our farm office start giving me a hard time.

They know what’s coming.

The soil fertility conversations start. I start looking at phosphorus and potassium levels, fertilizer prices, field histories, budgets and what we are planning to plant next year.

And somewhere along the way somebody usually suggests it’s about time for me to start taking Xanax (again).

They’re joking.

Sort of.

Because this is a part of farming that really does drive me crazy.

I’m the one in our office who keeps up with our soil fertility records and then takes recommendations from our crop consultants and tries to turn all of that into an actual plan.

And I want it to work like an accounting problem. And you should see my spreadsheet!  

If I spend another dollar here, tell me exactly what I’m going to get back.

Unfortunately, soil fertility doesn’t work that way.

At least it has never worked that way for me.

I’m not an agronomist although I know some agronomy. I know enough about fertility to keep the records, understand what our consultants are telling us, and I probably ask too many questions. When I get to the point where I’m uncomfortable, I call for help. There are a few people who have my number blocked, but it’s ok. I understand. I don’t want to talk to “me” either. 

And I ask things like:

How low is too low?

How much is enough?

Are we maintaining fertility or trying to build it?

If a field is testing well, can we back off a little this year?

If another field is deficient, how fast do we need to correct it?

If fertilizer prices are high, where should the next dollar go first?

And, of course, the question I really want to have answered:

What is this going to return?

That’s where it gets frustrating.

You can calculate exactly what a ton of fertilizer costs. You can calculate what a particular application costs per acre. You can calculate what the whole fertility program is going to cost the farm.

What you usually cannot calculate with the same precision is exactly what that dollar is going to return next year.

Some of what we apply is feeding next year’s crop, while some of it is just maintaining what we’ve spent years building. In another field, we may be trying to correct a real deficiency. And if we’re being truthful, sometimes we probably put out more than we really needed.

That uncertainty is what makes the budgeting side of this so difficult. And the price of fertilizer doesn’t help.

People will tell you there isn’t necessarily a right or wrong answer.

I think that fits soil fertility pretty well.

Sort of.

Because I do think there can be a wrong answer.

The wrong answer is to identify a real deficiency or need and simply ignore it.

After that, things get a lot less certain.

How quickly do you correct it?

Do you build fertility or just maintain it?

Do you do everything this fall or spread the expense over a couple of years?

Which fields get priority?

How much can the farm afford without creating another problem somewhere else?

There may be several perfectly reasonable answers.

The trick is to find the right answer for your farm.

And that is where I think the farm office meets the field.

The agronomist can tell us what the soil needs, and we’ve got the soil tests to work from. Then we have to look at fertilizer prices and figure out what the farm can actually afford to do.

Somebody still has to put all of that together.

Around our place, that somebody is usually me.



Which is probably why, about this time every fall, everyone starts asking whether I’ve filled my prescription yet!