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Sodic soil problems? Say "cheese!" (use of waste products from cheesemaking to make poor soil more productive)

To make poor soils more productive, waste products from cheesemaking may be the whey to go.

ARS soil scientist Charles Robbins found that acidic whey-the watery, nutrient-rich liquid that separates from curds in cottage cheese production-may restore the health of high-sodium soils.

Known as "sodic," these soils pose serious problems for farmers in arid, inigated regions like southern Idaho, according to Robbins, who is based at the Soil and Water Management Research Unit in Kimberly, Idaho.

The soils lack stable structure, or tilth. Water can't penetrate easily and simply flows off the surface, as if the soil were covered with plastic. Naturally, crops grown in these soils suffer from lack of water.

Over 1.8 million acres in the United States are classified as sodic, according to Dale A. Bucks, ARS' national program leader for water quality and management.

The unique composition of whey makes it an ideal supplement fox' sodic soils, Robbins found. Whey contains calcium, magnesium, phosphorus, and potassium, as well as sugars and proteins. The mixture helped restore soil tilth and boosted yields of barley in Robbins' initial greenhouse and small field plot tests.

To make cottage cheese, producers add concentrated phosphoric acid (or beneficial bacteria that produce the acid naturally) to a vat of milk. They then stir and heat it until the milk curdles. The remaining liquid is known as whey.

Robbins hit on the idea of using whey a few years ago while at a meeting about groundwater safety.

"I heard a talk about the problem of disposing of food-processing plant wastes," says Robbins. "When I saw the data on whey-how much the cheese factories produce, and what it's made of-it struck me that it might be a good treatment for our sodic soils."

Why whey? "The calcium, magnesium, and potassium present in whey actually replace the sodium in sodic soils. In addition, because whey is acidic (about the same pH as vinegar), calcium already in the soil is more soluble and will also replace sodium," explains Robbins.

Soil tilth improves, once the excess sodium is leached out. That in turn increases water infiltration in the soil, so thirsty plants can drink.

Other nutrients in whey, like nitrogen and phosphorus, also help nourish growing plants.

What's more, whey is abundant and inexpensive. For every pound of cottage cheese made, there are 9 pounds of whey produced.

According to Conly Hansen, a food engineer at Utah State University, cheese factories across the United States produce more than 2 million tons of whey each year.

Larger dairies dehydrate some of their whey and sell it to food companies. Dried whey protein is added to several food products like cake mixes, candies, and ice creams. And some whey ends up as livestock feed.

But a great deal-up to 50 percent-simply goes to waste, says Hansen. The factories actually pay to dispose of theh' excess whey through local sewage treatment plants, as is required by state environmental protection agencies or public health laws.

Robbins first tested the whey treatment in large plastic cylindrical columns in the greenhouse. The columns, known as weighing lysimeters, are a foot in diameter and about 3 feet tail, each holding about 300 pounds of soil. They enable researchers to precisely record weight changes from water (and whey, in this instance) added to the soil, to determine how much the plants use and how much is lost through evaporation. The lysimeters are equipped with sampling ports that allow him to collect subsurface water draining from the columns and analyze it for sodium and other compounds.

The control treatment (no whey) produced barley that didn't "fill," or produce grain. The best whey treatment yielded barley at a rate equivalent to ,$2 bushels per acre. With continued whey treatments, that could improve up to 80 bushels per acre, says Robbins.

Outdoor field trials have shown similarly positive results. For those tests, Robbins applied the whey to the field using plastic irrigation pipes. It can't be run through aluminum pipes, because its acidity would eventually dissolve the metal.

Whey applications were made during the spring and late fall and plowed into the soil immediately before planting. It's usually quite cool at those times of year, so there's no odor problem.

Robbins is also testing the use of whey on eroded and leveled nutrientpoor soils. Such areas may suffer productivity losses up to 50 percent.

He's comparing two different whey application levels with manure and conventional fertilizer, on exposed subsoils. Three different cropsalfalfa, forage sorghum, and dry pinto beans-will be grown in different rotations on the plots.

These long-term studies should help researchers determine the optimal amounts of whey to use for restoring soil physical conditions and crop productivity, according to Robbins.

"I'm very excited about the idea," says food engineer Hansen. "This is one solution to our whey disposal problem that seems to have great possibilities."-By Julie Corliss, ARS.

Charles Robbins is in the USDAARS Soil and Water Management Research Unit, 3793 N, 3600 E, Kimberly, ID 83341. Phone (208) 423-6530.
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Author:Corliss, Julie
Publication:Agricultural Research
Date:Mar 1, 1992
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