WASHINGTON, March 29 (Reuters) - U.S. soybean plantings will be unexpectedly lower this year as farmers cut their acreage devoted to the oilseed by 1 percent amid sharply rising supplies, the U.S. Agriculture Department said on Thursday.
Corn acreage also will fall from 2017 while wheat seedings will rise by 3 percent, according to USDA's annual prospective plantings report, which is based on surveys of nearly 83,000 farmers taken during the first two weeks of March.
USDA said that soybean plantings, despite the expected drop, will top corn acreage for the first time since 1983. Both soybean and corn stocks stood at their highest totals ever for March 1.
The government said soybean acreage will total 88.982 million in 2018, down from 90.142 million acres a year ago. Analysts' forecasts for soybean acreage ranged from 89.900 million to 92.600 million, according to a Reuters survey.
U.S. soybean supplies as of March 1 totaled 2.107 billion bushels, up 21 percent from a year earlier, USDA said in its quarterly stocks report. That was near the high end of forecasts ranging from 1.810 billion bushels to 2.110 billion bushels.
Soybean stocks were on the rise as China, the world's largest soy importer, has focused on Brazilian supplies to meet its needs because the massive crop harvested by U.S. farmers in 2017 suffered from low protein content.
USDA predicted that corn acreage will drop to 88.026 million from 90.167 million a year ago, near the low end of analysts' estimates that ranged from 87.550 million acres to 91.000 million acres.
U.S. corn stocks as of March 1 stood at 8.888 billion bushels, up from 8.622 billion bushels a year earlier and above analysts' expectations that ranged from 8.550 billion bushels to 8.881 billion bushels.
All wheat seedings were predicted to rise to 47.339 million acres from 46.012 million a year ago. That compares with analysts' forecasts for 43.900 million to 47.200 million wheat acres.
USDA forecast that farmers will boost their winter wheat seedings and spring wheat other than durum seedings. Durum acreage was seen falling 13.1 percent from 2017.
Wheat stocks as of March 1 fell to 1.494 billion bushels from 1.659 billion bushels a year earlier. Analysts had been expecting wheat stocks of 1.498 billion bushels, according to the average of estimates in a Reuters survey.
(Reporting by Mark Weinraub Editing by Paul Simao)