BUENOS AIRES, April 17 (Reuters) - The Iran war has strongly boosted prices of the urea fertilizer that is vital to ensuring a successful wheat harvest in Argentina, forcing farmers into a bind weeks before the crop's season begins next month.

A nearly 100% increase in the price of urea - a fertilizer that provides nitrogen - as a result of the war that began in late February has forced many local producers to evaluate whether to reduce their applications of the product or abandon planting plans.

"We did the math the other day and our idea boils down to two options: either we don't grow wheat and we plant something that will be useful to me for livestock, like barley or oats, or we do it but with very little fertilizer, not thinking about high yields," Roman Gutierrez, an agricultural producer from the town of Pergamino in Buenos Aires province, told Reuters.

Urea is now at $1,000 per ton - up from about $500 just over a month ago, according to Gustavo Churín, an analyst who follows the fertilizer market. He attributed the surge in price to the contraction of the global supply of urea from Persian Gulf countries because of war and its impact on trade that utilizes the Strait of Hormuz.

A record 29.5 million tons of wheat were harvested in Argentina's last wheat season, according to data from the Rosario grains exchange, where Argentina's main grain market operates. The board has not yet published estimates on the upcoming wheat harvest.

UREA'S CRUCIAL ROLE IN CROP YIELDS

Argentina uses approximately 2.5 million tons of urea annually. In addition to wheat, it is used in corn production and helps with the development of plants.

Urea is "the master key that allows you to aspire to other levels of yields," said Cristian Russo, the head of agricultural estimates at the Rosario grains exchange. 

However, in Venado Tuerto, a town in the fertile plains of the province of Santa Fe, producers have been forced to cut back. Local farmer Noelia Castagnani said that farmers are not purchasing urea and may shift their focus from wheat to increasing their corn or soybean acreage when it is planted later in the year.

"There aren't that many inquiries about fertilizers," said Castagnani. "The profit margin is very limited."

Churin said that a cessation of hostilities in the Middle East would not immediately return urea prices to pre-conflict levels but would provide some relief.