U.S. farmers planted more corn than expected and a record amount of soybeans despite a wet, cold spring that slowed field work, the government said on Friday.

The large plantings put corn and soybean crops near records that would end three years of tight supplies and high prices. Corn plantings were the largest since 1936.

In a companion report, the U.S. Agriculture Department said corn, soybean and wheat stockpiles were smaller than trade expectations, as of June 1. But stockpiles were far from the extreme shocks that the USDA sometimes delivers in the quarterly data, which show the pace at which grain is being used.

"The corn acres number is the big story," said Joe Vaclavik, president of Standard Grain.

Corn and wheat futures prices tumbled after the report was released, with soybean values choppy. Corn was down about 1 percent, and wheat dropped almost 2 percent.

New-crop corn futures fell heavily on the acreage figure, down more than 4 percent to test the lowest levels of the year. New-crop soybean futures were also weak, while nearby months drew support from tight supplies expected between now and harvest.

"Stocks report was bullish, acreage was bearish, any other questions? Looks like the trade was awaiting the numbers to sell the market, and they did it in style," said Charlie Sernatinger, analyst at ED&F Man.

Based on a survey of 70,000 farmers, the USDA pegged corn plantings at 97.379 million acres, 2 million acres, or 2 percent, more than expected by analysts.

"It was mostly the planted acres that caught people by surprise and justifiably so. They're extremely high numbers for planted acres," said Jack Scoville, an analyst at the Price Futures Group.

The USDA said corn acres rose for a fifth year in a row.

Soybean plantings were a record 77.728 million acres, up 1 percent from last year, but 200,000 acres lower than the average forecast.

Farmers could harvest a record 13.9 billion bushels of corn, 3.4 billion bushels of soybeans and 2 billion bushels of wheat, USDA's planting figures suggested, with normal weather and yields.

Rainy, snowy and cold weather put spring planting weeks behind its normal pace in much of the Farm Belt during April and early May.

Based on the conditions, analysts expected farmers to shift some land to soybeans and cotton, which can be planted later, and away from corn and wheat. They also looked for overall plantings to fall short.

But improved weather in late May and June allowed farmers to catch up, to a large degree.

Spring and durum wheat plantings were smaller than expected. Wheat plantings in North Dakota, the No. 2 producer, are down 10 percent from what growers planned in March.

Cotton plantings rose to 10.3 million acres from the March estimate of 10 million acres. Plantings are down 17 percent from last year.

Corn stocks are projected to dwindle to their smallest amount in 17 years by the time this year's potentially huge crop is ready for harvest.

In rain-logged Iowa, No. 1 in corn and soybeans, corn acreage was down by 200,000 acres from the March estimate and soybeans were up by 100,000 acres. Nebraska and Minnesota corn plantings were down by 200,000 acres from the March estimate.

At the start of this week, the corn crop nationwide was lagging slightly on its usual rate of development but especially so in rainy Iowa. Soybeans were well behind normal in Iowa, Minnesota, Wisconsin and Missouri. In North Dakota, corn, soybeans and wheat were all significantly behind normal.

Late-developing crops are more at risk from summer heat waves or early freezes. (Reporting by Charles Abbott; Additional reporting by Julie Ingwersen and Michael Hirtzer; Editing by Ros Krasny and Jeffrey Benkoe)