Mr Carter was addressing Federated Farmers' high country conference in Christchurch.
To "gouge" $800 million from farmers "just when the planets are finally aligned with all the primary sectors showing good prospects" would tax about $33,000 on average from every genuine sheep/beef and dairy farmer in the country.
Mr Carter described Labour's proposal as another example of the party's "politics of envy".
National was committed to a fairer and more equitable pastoral lease rental system for high country farmers.
The Crown Pastoral Land Amendment Bill was before the Primary Production Select Committee.
Federated Farmers' high country committee had made a submission, recommending some improvements.
If the Bill was not passed before the general election, he gave an assurance it would be done "as soon as possible" afterwards.
While New Zealand was recognised internationally as having a very good biosecurity system, risks existed every day and the system needed to be constantly reviewed, Mr Carter said.
The Biosecurity Law Reform Bill was before Parliament and it proposed various changes, including government industry agreements.
"[Government industry agreements] will ensure we are better prepared by working with industry prior to an incursion, rather than dealing with it after the event. It's the ambulance at the top of the cliff, not the bottom."
Strengthened partnerships between industry and government would lead to better results in dealing with incursions of pests and diseases, he said.
