As expected, the government has chickened out on agricultural emissions. Given the option to put farmers in the ETS and make them properly pay for their pollution like the rest of us, they have instead decided to threaten them with it, in the hope that this will cause climate-change denying industry groups to come up with a scientifically robust on-farm emissions pricing scheme within five years. Which is about as likely a prospect as the UK Conservative Party coming up with an effective plan for Brexit.
Because the central problem here is that the industry groups the government is calling its "partners" are fundamentally opposed to farmers taking any responsibility for their pollution. They have denied and dragged their feet every step of the way, opposed paying for research to reduce their emissions, opposed best practice when its been proven to do so, opposed farmers doing anything different from what they do now. There's no indication that they have changed their views or will suddenly start acting in good faith. Instead, what it gives them an incentive to do is wait for a change of government, then push for the "backstop" to be repealed, so the free ride - which has been going on for 16 years already - can continue forever. And meanwhile, the 86% of us who live in cities are paying for every gram of carbon we emit.
But while the government is pandering to a tiny noisy rural elite, the rest of us need to confront the facts. Agriculture is responsible for ~50% of our emissions. We can not meaningfully reduce our emissions unless we also reduce those from agriculture. Anything which delays doing that is effectively a recipe for failure, and any government which condones such a delay is selling our future. It is that simple.