The worst drought in more than a half century is turning corn fields in many parts of the central portion of the nation into dried-up disasters.

But things are much different here.

In the Tracy area and throughout San Joaquin County, what could be the largest corn crop in the county’s history is flourishing under sunny skies and with what many growers in the Midwest and Great Plains, who depend on rain for moisture, would love to have — irrigation water.

The irrigated stalks of corn — for animal feed, corn products for human use and silage for dairy cows — are growing tall, as high as the proverbial elephant’s eye, if that eye were at least 10 feet high.

South of Tracy, near the corner of Schulte and Chrisman roads, grower Philip Martin was checking over a 60-acre corn field earlier this week.

“So far, the corn is looking good, and we should have a pretty good crop — how good I’ll know in a couple of weeks, when the ears are farther along and we can tell what impact hot weather has had on pollination,” he reported.

And yes, he said, irrigation every 10 days or two weeks is essential to the growth of the corn in the field.

Martin, who has been growing corn for the past quarter-century, said the 60-acre leased field he was checking with his 5-year-old son, Philip IV, had been planted with a variety of corn for human consumption — to be used for tortilla chips, cornmeal and other corn-based products.

Most of the 700 acres of corn he is growing this year, in fields scattered throughout the Tracy area, is planted in a more standard variety of grain corn, ears that are mostly turned into animal feed. The rest — ears and stalks — is chopped for silage, mostly for dairy cattle.

San Joaquin County is the largest producer of corn in California, according to Scott Hudson, San Joaquin County’s agricultural commissioner. Last year, farmers in the county harvested 109,200 acres of corn — 63,000 acres of grain corn and 46,200 acres for silage, reported Hudson. This year, more corn has been planted, and although county totals have not been tabulated, California corn acreage is up 29 percent to an all-time high of 670,000 acres.

“That ratio of grain to silage corn in the county has been about average each year,” Hudson said. “The grain corn is heavy in the Delta, and silage is more prevalent in the areas close to dairies.”

Corn — both grain and silage — generated $130.3 million in revenue in 2011 in San Joaquin County, making the combined total the fifth-most valuable crop in the county in 2011, part of a county-record $2.2 billion in agricultural revenue.

With the planting of grain corn in 2011 up 73 percent from 2010, revenue increased from $42.7 million in 2010 to $67.6 million last year.

Silage corn, with fewer acres planted than in 2010, generated $62.7 million in revenue last year, slightly more than 2010.

Even before the drought descended on parts of the Midwest and Great Plains in recent months, 2012 corn planting in California had increased to 670,000 acres, eclipsing the 600,000-acre record set in 1998.

Across the nation, U.S. farmers planted 92.9 million acres of corn this season, 19 percent more than last year. The planted acreage is the highest since 1944, when 95.5 million acres were planted. Last year, 40 percent of the U.S. corn crop — mostly from the Midwest and Plains states — was used to produce ethanol for fuel.

Despite the increase in acreage, the severe drought, described as the worst since the 1950s, may lead this year to the smallest nationwide corn crop since 2006.

According to the U.S. Department of Agriculture, 88 percent of the corn crop is now hurt by the drought. And corn is selling at record high prices, close to $8 a bushel, 50 percent more than a month ago.

How the green in the local irrigated corn stalks translates into green in farmers’ wallets will depend on a number of factors, including yields, prices, production costs and futures contracts.