Ramon Ayala has been a U.S. citizen since 1975, and he says about half the workers on his farm are citizens.

Because citizenship is so valuable to him, he encourages all of them to go through the required steps, including the language requirements.

"I want them to learn English," he said. "It's good for everybody."

Language can be a barrier for immigrants. Along with showing a basic knowledge of U.S. history and government, applicants for citizenship are required to display an ability to read, write and speak ordinary English.

In 1999, the U.S. Census Bureau surveyed 14,000 people and concluded that an estimated 47 percent of documented immigrants who had been in the U.S. at least 10 years had not become U.S. citizens primarily because of their inability to speak English.

Washington State University Extension's Bee Cha said many Hmong farmers have become citizens despite having no language services available to them.

"I have very small idea of how they are able to communicate with their customers," he said. "I think they sell very fresh produce and flowers at low price, and that is their communication with buyers. There are no classes, and so their interaction at the markets is their main learning channel."

The decision to become a naturalized citizen is not a difficult one, he said, "but the process is."

The English proficiency requirement especially affects the elderly, keeping many older immigrants from ever filing for citizenship.

However, the U.S. Citizenship and Immigration Services describes special exceptions for older immigrants who have lived in the U.S. as permanent residents for certain periods of time:

* Age 50 or older at the time of filing for naturalization and have lived as a permanent resident (green card holder) in the U.S. for 20 years (commonly referred to as the "50/20" exception).

* Age 55 or older at the time of filing for naturalization and have lived as a permanent resident in the U.S. for 15 years (commonly referred to as the "55/15" exception).

The agency points out that even those qualifying for the language exceptions must still take the civics test.

The cost to apply for naturalization is $595 plus $85 for the biometric fee, which covers fingerprinting and any other personal data.

According to the USCIS, more than 1,980,000 naturalization tests were administered nationwide from Oct. 1, 2009, through June 30, 2012. It reported that as of June 2012, the overall nationwide pass rate for all applicants taking both the English and civics tests was 92 percent.