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Serving: IN

Great Time To Apply Phosphorus and Potassium

Great Time To Apply Phosphorus and Potassium
Take advantage of good weather after harvest to broadcast nutrients.

The late fall forecast still talks about rain and cooler temperatures. If you get crops harvested and have a dealer ready to spread fertilizer, or else have an employee who dos it with your equipment, now may be the time to apply it.

"P and K tend to stay put where you apply them, so there is typically not a lot of risk about loss from fall applications of these nutrients," says Brian Early, a DuPont Pioneer production agronomist in northeast and east-central Indiana. Before his career with Pioneer, Early operated his own business as a crops consultant, doing plenty of soil testing and making lots of fertilizer recommendations.

Time to apply: Once crops are harvested and if soils are still dry, it's a good time to make fall applications of P and K, Brian Early says.

Some ask him if it's OK to apply P and K in the fall even on sloping soils. His answer is typically that it is probably OK, as long as gullies aren't likely to form with big rains. A big rain coming soon after application could cause some loss of P and K even on soils with lesser slope, he notes.

Early observes that more and more customers are tending toward using their yield maps to calculate what the crop removed, and then applying P and K to meet crop removal amounts. Some are using variable-rate application to fine-tune how much they apply in various parts of the field.

He believes that applying based on crop removal is a good option, as long as your soils are in good shape on soil fertility anyway, at least as far as P and K goes. Most Indiana soils naturally tend to be relatively higher on P compared to K levels, but in the end, it depends largely on past fertilizer application practices.

He follows that recommendation with a strong push for routine soil testing to monitor nutrient levels. Often if you're on a soil testing program, each field will be sampled once every three or four years.

"That is a report card on how well you're program of applying to replace amounts removed by crops is working," he says.

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