Pass The Potatoes!
October 1998

Some like them fried, some like them mashed, boiled or roasted. Others like them scalloped, baked or even double baked. Some like them white, brown, purple, red or gold. No matter how we slice or dice them, the humble potato is a diet mainstay of the world. Considered by many to be a native of the Peruvian-Bolivian Andes, the potato is one of approximately 150 tuber-bearing species of the genus Solanum. It differs from other crops in that the edible part of the plant is a tuber; i.e. the swollen end of an underground stem.

Easy on the butter, heavy on the boron

The unassuming spud or potato is dependent on a modest element known as boron. Boron is a naturally occurring element present in all soils and the ocean. One of boron's claims to fame is that it makes the potato and nearly every vegetable and fruit crop healthier - and more marketable. Boron is one of the seven essential micronutrients, and our knowledge of boron and potato plant health comes from 75 years of research and the experience of farmers and field advisors.

Recent studies indicate that boron has a beneficial effect, along with potassium and calcium, on the internal quality of potatoes. Boron, for instance, is essential for movement of calcium around the plant for correct calcium nutrition.

Says Mike Hunter, North America market manager for Phosyn, an international nutrient manufacturer company with an office in Ephrata, Washington, "We're doing a nutrient profile on potato tubers in the Columbia Basin (Washington State) and the world, and are trying to determine quantity and quality relative to the nutrients in tubers." His field experience shows that when boron is applied in the early stages of the cell division process (the first 14-30 days after tuber initiation) of the potato, there is better uniformity of type. "We find this applies in other crops too, such as apples and strawberries," says Mike.

"There is more to fertility management than the well-known NPK (nitrogen, phosphorus, potassium) mixture, Mike points out. He focuses on total plant nutrition and the needed secondary and trace elements for proper utilization of the primary nutrients. Following critical soil sampling and potato tissue analysis, he counsels field advisors as to what levels are low of these elements or micronutrients. The proper mix of fertilizers can then be recommended to the farmers. A complete analysis eliminates any guesswork.

Former president of the Potato Growers of Washington State, Greg Richardson of Richardson & Strong Farms in Quincy, Washington, makes sure his potato farming is accurate and not a guess. "First, I have soil analysis done," he says. He then has tissue samples taken from the midrib of the potato leaf and from the tubers (or potato body). Based on the results, Greg and a local distributor decide on the amounts of certain nutrients needed, including boron, and when it's best to apply them.

Boron deficiencies in the potato appear as internal brown spots, black spots, brown centers and hollow hearts. Not enough boron reduces the yield and quality. On the other hand, excess boron can reduce yield and quality, so it is important to get the application right. But boron has been found not only to make potatoes grow right, but to grow better.

A Cornell University study by Nell Mondy and Cyrus Munshi in 1993 found that the use of a boron foliar spray during the growth of potato plants significantly decreased enzymatic discoloration and phenolic concentration in the tubers. And one of the chief nutrients in the potato, vitamin C, important especially since the potato is known to supply up to 50 percent of the required daily allowance of this vitamin, was also significantly increased by boron supplementation. The increase in vitamin C concentration due to boron fertilization makes the tuber more nutritious. The study concluded by saying that overall tuber quality was improved by boron foliar spray.

In sandy or silt loam soils where potatoes grow best, boron is often lacking. It is in places like this, as in the soils of the Columbia Basin, field advisors strongly recommend boron.

"I use it (boron) and always have," says Arnie Greenwalt, a field advisor for Quincy Farm Chemicals in Washington. Quincy Farms buys the full range of 20 Mule TeamŪ borate miconutrients: SoluborŪ soluble borate, GranuborŪ granular borate, and FertiborŪ fertilizer borate. "I've made sure that I recommend boron for potatoes," says Arnie.

One of his clients is Paul Morris of Morris Farms, whose family-owned business produces more than 8,000 tonnes of potatoes per year. Morris potatoes are shipped fresh to the market or delivered for processing where they are cut for fries or dehydrated for flakes. Before Paul's planting begins, he has soil samples taken and nutrient recommendations made. Arnie determined that two pounds or a kilogram per acre of Granubor are needed for preplant this year for Paul's Russet Burbanks and Norkotahs. Granubor is applied as a mix with nitrogen, phosphate, potash and sulphur. As an option if needed, Solubor can then be used as a foliar spray, 40 to 60 days after planting. "I know boron plays an important part in root development of the potato," says Paul.

In addition to root, leaf and bud development, boron is involved with calcium in the cell wall structure. According to the Potash & Phosphate Institute, it has been seven decades since scientists first demonstrated the necessity of boron for plant growth. It is an essential nutrient needed by the plant to properly utilize sunlight, water, and air. Because of its role in the cell wall, boron is critical for all aspects of growth including top growth to ensure optimum utilization of sunlight; root growth, essential for uptake of water and nutrients; and ultimately tuber growth.

Paul Morris, like other growers, must make a return on his crop. He says that by the time he pays for fertilizer, seed, water and pest control his investment is $2,500 per acre. So, producing a quality potato and lots of them is critical and boron helps him to do this.

To help improve the return on investment in the San Luis Valley of Colorado, a field study this year is being sponsored by Colorado State University (CSU) and U.S. Borax to determine the effects of boron in potatoes in that region. The two-year study, directed by Jessica Davis of CSU and John Mortvedt, a Borax consultant, will be investigating the "hidden hunger" of the potato, where boron levels in the soil or leaf may read adequate, but plant parts will respond to supplemental boron sprays. The Colorado region research is aimed toward finding the best boron applications, and is one of many boron-application studies funded by Borax to support growers' efforts to produce high quality crops of all types.

So whether you grow them or just like to eat them, remember the humble potato has an essential and economical micronutrient called boron to credit for its higher yields and crop quality.

Hot potato regions

Washington and Idaho states have some of the best growing areas in the U.S. Washington with 150,000 acres has approximately 33 tonnes yield per acre, and Idaho with its 450,000 acres has 16-22 tonnes yield per acre. What makes for good potato-growing conditions are warm daytime temperatures and cool night temperatures. Other areas that fit these conditions are Oregon, regions along the Mississippi River in Missouri, North Dakota, and central Wisconsin. However, even the best potato growing areas can benefit from added Granubor or Solubor fertilizer borates, providing a sure return on the farmers' investment. Application rates vary depending on local conditions.