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The Marine Corps uses the 7P model: Proper prior planning prevents poor performance. Of course, I’ve cleaned that up a bit. In business, we create budgets, marketing plans, logistics strategies, and investment goals. In farming, we do the same, but when it comes to fertility, we often fall back on, “This is what we’ve always done.”

It’s time to be more aggressive and intentional with our fertility strategies.

Challenge the Nitrogen Habit
A large grower and client of mine told me last year, “Your proposal sounds great, but don’t touch my nitrogen amounts!” He wanted to keep all applications from previous years the same. Our compromise was adopting a spoon-feeding approach, smaller shots at each fertigation.

As the season progressed, we may have saved significant money by backing off the N when leaf tissue results showed levels well into the “green.” But other nutrients remained at insufficient or barely sufficient levels, and more importantly, they weren’t balanced.

We need to pay more attention to how each nutrient, especially the macros, compares to nitrogen. Typically, July tissue samples in the 2.5% to 2.9% nitrogen range are ideal. Some labs call phosphorus (P) levels of 0.11% insufficient. I beg to differ.

Phosphorus starts high, like nitrogen, then tapers off. Even in good years, 0.25% P is considered a luxury level. But that’s only about 10% of ending N, not starting levels. Phosphorus is essential in ATP production in both the Krebs and Calvin cycles, 32 molecules of it, to be exact. That’s a lot of P on the cellular level.

I’d like to see P at about 7% of N to start. If N is 4, then P should be 0.28%. That’s a tough number to hit, especially since P is hard to get into plants in the cold, wet spring. That’s why a good post-harvest plan is critical.

If you made post-harvest P applications, be ready to follow with early spring foliar and soil-applied orthophosphate.

Sulfate Overload Can Limit Cations
Sulfur is another macro that can be problematic. It’s crucial for protein synthesis, and with high-pH ground, we often inject sulfuric acid to drop soil pH. We also apply calcium sulfate (gypsum), potassium sulfate (SOP), zinc sulfate, and more.

But sulfur attaches to oxygen, forming sulfate (SO₄²– ), which aggressively binds with calcium, potassium, zinc and iron—sometimes more aggressively than plant roots can. That creates tie-up and unavailability.

Check your soil tests. Many labs list a “sweet spot” for soil sulfate at 6–15 ppm. But how many of your soils are 30? 50? 200? Even 900 ppm? I’ve seen it all. You might be hurting your fertility program by overapplying the sulfate salt of a cation you’re chasing.

I’ve never seen a toxic sulfate response, and neither has our agronomist at Ultra Gro, Robert Smith, but we’ve seen many cation deficiencies in high-sulfate soils. Aim to keep sulfur levels at about 15% of N in your tissue tests, and reduce soil S where it’s excessive.

Manage Calcium With Timing and Form
Calcium doesn’t play well with others, especially phosphate. Apply them separately and use a dual-approach strategy: one in a spray (“upstairs”) and one through fertigation (“downstairs”). Switch up the next time through the orchard.

I typically want calcium to equal nitrogen early in the season, using plant-ready calcium. For those with gypsum machines, remember that soluble and suspended calcium are not the same. Finer particles dissolve better, but it still takes time. If you need calcium now, use a proper solution.

Calcium is immobile in plants. Once it finds a home in a cell wall, it stays there. That’s why tissue levels rise all season, and it’s not uncommon to see 4–5% calcium by the end of the season. Just remember: we’re testing leaves we can reach, not the new growth 25 feet up. Until we have a better way, keep the levels up.

Without a Plan, It’s Just Hope
Farming is hard. If we aren’t following a well-thought-out plan, we risk falling short of our potential. And let’s be honest, we farmers want it all.

We may shoot for yields triple the industry average, but our soils and water may only allow us to hit the average even when we do everything right. Without a plan, it’s darn near impossible to keep up.