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Corn+Soybean Digest

Are You Throwing Away Fertilizer Dollars?

Some shocking soil pH levels are turning up in the hinterlands - and it's costing growers money.

There's more than one reason, of course. But the big one is absentee land ownership - people who know little about soil management.

"Believe it or not, we are seeing soil samples come into our diagnostic lab with soil pH levels in the low 5 range, and even some in the 4 range," scolds Ellsworth Christmas, extension agronomist at Purdue University. "It produces poor nodulation on legumes like soybeans, lower yields and wastes fertilizer efficiency. I think this liming factor is being overlooked too often."

The story is the same all over the Corn Belt, adds John Creswell, Iowa State University crop specialist. "Here in Iowa, for example, growers have really pushed the nitrogen, phosphorus and potassium, but they are letting soil pHs get into the mid-5 range, and that's hurting.

"Research shows that, when soil pH gets below 5.9 or 5.8, you're losing soybean yield, and you are losing money on your fertilizer dollars," declares Creswell. "You're simply not getting the full bang for your buck."

A few renters, especially those in share-crop leases, have convinced landlords that they will get more return by keeping the soil pH at an acceptable level.

In land rental agreements, liming, if needed, is usually the responsibility of the landowner because it's an investment that lasts several years. The fertilizer, unless all costs and profits are shared, is the renter's responsibility.

"I think one of the things that would help avoid this low soil pH situation is if a tenant could get a clause in his rental agreement that lists a minimum pH at which the soil needs to be maintained," explains Christmas.

"I know of landlords who do the opposite to the tenant. They insist the tenant must apply X number of pounds of phosphorus and potassium on an annual basis to maintain the soil fertility at a medium level. That's their protection against a tenant mining the soil to cut costs and boost profits, with no regard to the long-term productivity."

Christmas suggests that the flip side of that equation ought to be considered in written leases, where the landlord is responsible for holding the soil pH at a certain minimum level of, say, 6.2 or higher.

"Too many landlords don't want to make any investment, or make only minimal investment, and that is hurting yields and fertilizer-use efficiency," he says.

In Iowa, Creswell points out, the situation has been alleviated in some instances. The tenant picks up the cost of the lime, but the investment is protected by spreading it over several years in a multiyear lease. And, if the lease is terminated early, the landlord reimburses the tenant for the appropriate amount of that lime.

What about the cost of liming?

Lime can be fairly pricey, depending on fineness of grind and hauling distance. But a 2- to 4-ton rate would come to $20 to $40-plus per acre - still a long-term bargain, say scientists.

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