A second fake organic fertilizer seller in California has been sentenced to prison in federal court this month.

Kenneth Nelson, 59, was sentenced to 61/2 years in federal prison, three years supervised release and ordered to pay $9 million. He was also ordered to forfeit several vehicles and may owe additional restitution.

Nelson pleaded guilty earlier this year to several counts of mail fraud for representing fertilizers as organic that actually included banned materials, including aqueous ammonia, ammonium sulfate and urea.

The scheme involved submitting fake documentation to state agriculture officials in Washington and the Organic Materials Review Institute, which verifies products meet organic criteria, according to the U.S. Department of Justice.

The agency said Nelson sold organic farmers and dealers more than $40 million worth of the products, netting a profit of more than $9 million between 2003 and 2008.

Earlier in November, Peter Townsley, 50, was sentenced to nearly one year behind bars, three years probation, a $125,000 fine and other conditions for selling fake organic fertilizer.

According to the U.S. Department of Justice, Townsley sold about $6.5 million worth of fertilizer that was labeled as organic but actually contained prohibited types of synthetic nitrogen.

-- Mateusz Perkowski