The ICMSA has threatened a national campaign in defence of farmer access to third-level education grants.
The move follows the refusal of Education Minister Ruairi Quinn to rule out farm assets from any future means testing arrangements for college grants.
In a letter to the ICMSA, Mr Quinn emphasised his commitment to overhauling the current system of means testing for college education grants.
He stated that a dedicated Capital Asset Test implementation group was working on how best to roll out a means test that included family assets.
The new means test is due to be introduced for the beginning of the 2013/14 academic year.
In response, the ICMSA promised to fight the introduction of asset tests 'tooth and nail'.
ICMSA president John Comer said asset tests would discriminate against the children of farm families by unfairly restricting access to higher education grants.
"We will be contacting every rural TD in the State to alert them to the implications of such a move," Mr Comer said.
"It is obvious that the desired goal here is less farmers' sons and daughters qualifying for the grants," he said.
According to the latest figures from the Higher Education Authority (HEA), farmers' sons and daughters accounted for less than 8pc of all the third-level grants awarded for the 2010-2011 academic year. This is half the number of grants being awarded to either professionals, employers and managers or skilled and semi-skilled workers.
In addition, just 40pc of farm children who attended college last year received grants. This is higher than the average, which stands at 33pc. However, Mr Quinn acknowledged to the ICMSA that this figure was "lower than urban myth would have it".
Of the 11 socio-economic groups surveyed by the HEA, six had a higher percentage than farmers qualifying for grant aid.
In a reply to the ICMSA, Mr Quinn stated that the current means test was "at variance with other major financial support schemes".
He added that a number of reports produced by the Department of Education in recent years had "strongly recommended the introduction of a capital test for student grants to create a more equitable basis for means testing, based on a more complete analysis of a family's capacity to support their children".
"The objective of the student grant scheme is to target available funding at socio-economically disadvantaged groups," Mr Quinn said.
He also insisted that he "did not wish to see students from less well-off farm families excluded from grant eligibility."
However, this assurance did little to convince Mr Comer of the merits of the changes.
"If this proposal goes ahead, then the children of the typical full-time farmer will never qualify for a higher education grant," Mr Comer said.
"It seems that high value, readily saleable residential property will be excluded from any formula to determine eligibility. ICMSA will begin immediately to lobby against this move."