The union made the pledge after the Government announced in this month's budget that it intends to publish a consultation this summer on proposals to "simplify the agreements".
An NFU representative, speaking in a newsletter sent to its horticulture members this month, said: "We already know Government intends to simplify CCAs to maximise outputs in terms of carbon savings and to minimise the cost of administering the agreements. But to be clear, when we talk about minimising administrative costs we are talking about Government costs."
The NFU fears any changes could "just mean a shift of that (administrative) burden from Government on to businesses participating in CCAs".
"For many smaller businesses, such increased costs could mean it is no longer economically viable for them to participate and, as a result, the climate change levy for them will just become another tax they have to pay and are unable to recover."