What’s the big deal about soil testing?

CORTLAND, Ohio — With fertilizer prices on the rise, farmers are scrambling to keep their profit in their wallets instead of putting it on their fields.

While skipping the fertilizer altogether isn’t a very good idea, two researchers from Ohio State University say there’s at least one simple thing producers can do to save money: Get a soil test.

When fertilizer was cheap, it didn’t hurt a farmer financially if he applied too much, said Robert Mullens, an OSU extension state agronomy specialist. But with prices climbing higher and higher, buying fertilizer can be a dangerous game for those who don’t do their homework.

For instance, potassium and phosphorus prices are rising dramatically, according to OSU extension economist Barry Ward. On average, the price of phosphorous fertilizers is expected increase about 65 percent from 2007 to 2008. Potassium prices are forecasted to rise 40 percent over last year’s costs.

Ed Lentz, an OSU crop specialist, said soil sampling isn’t an exact science and the test results won’t necessarily show you a right or wrong answer. But using those results can be a useful guide in making fertilizer decisions.

Mullens and Lentz spoke Jan. 30 at the Soil Fertility and Nutrient Management Workshop in Trumbull County. The workshop covered soybean production, starter and foliar fertilizers, soil tests, soil pH and lime, and phosphorus, potassium and nitrogen recommendations.

According to a USDA Economic Research Service report, less than 40 percent of U.S. corn acreage was soil tested in 2000. Mullens said it’s likely that number has increased, but there are still farmers missing out on the chance to save some cash.

At the workshop, the OSU experts offered a few basic soil testing tips:

1. Know how to sample.

The information revealed by a soil analysis is only as good as the soil sample, Lentz said.

You should try to collect 15-20 random samples from throughout your field. Be consistent with your sampling depth, which should be around 8 inches.

Don’t sample in extremely dry or extremely wet conditions, but do sample at the same time every year.

If you aren’t comfortable doing this yourself, there are plenty of experts out there willing to help.

2. Learn to interpret results.

According to Lentz, a soil analysis report has three sections — real numbers from the soil sample; a chart that determines if those numbers are low, medium or high; and fertilizer recommendations.

Many people look at the low/medium/high chart or simply go by the recommendations, but that’s not how to get the most bang for your buck.
While the chart is a nice visual feature, it’s mainly a marketing tool. And those low/medium/high rankings are subjective.

“You’ve got to understand the real numbers to know if it’s low/medium/high,” Lentz said.

And you need to know if those written recommendations actually reflect what the real numbers show.

“Always be sure the written part matches back to the real numbers,” Lentz said.
The crop specialist added that although every lab issues its own type of analysis report, there are four things a producer should always look for: soil pH, buffer pH, phosphorus and potassium.

3. Decide what’s right for you.

“There is no cookie-cutter approach for fertility management because everyone has different soils and different cropping systems,” Mullens said Jan. 31 in a university press release.

But having your soil analyzed can give you a better idea of whether you need to buy up, back off or sit tight.

“Sometimes the decision is ‘do nothing,’” Lentz said.

It just depends on the individual situation.

Producers also have to consider conditions specific to their farm. For instance, if the field is in a rotation, what crop is going in next year?

And although there is some cost associated with a soil test, Lentz said that’s not an excuse to forgo the process.

“If you can’t pay for a soil test today, you’ll never be able to pay for it,” he said. “This is a prime opportunity.”