The can of WD40 is empty. The putty repairing the holes in the pan beneath the grain sieves on my increasingly ancient John Deere combine harvester has set. So my harvest is under way and – in stark contrast to last year – bountiful.

But as the grain store fills up, my joy is tempered by the knowledge that this year represents the last year of my long-cherished status as a continuous cereal grower. Other, braver souls have gamely taken the plunge with a variety of break crops ranging from peas and beans to oilseed rape. For the past 40 years, I have mostly plugged on with a continuous cereals policy.

This determination to stick with wheat and barley was imbued in me by my splendid ADAS crops advisor of the 1980s and 1990s. He and I stuck doggedly to continuous cereals in those days, even though it was already becoming increasingly less fashionable in combinable crop circles.

As he used to remind me, as we surveyed problems with wild oats, blackgrass and other invasive grasses like sterile or soft broom, their impact on cereal yields was limited. Okay, my crops looked a bit messy but, provided I wasn’t thinking of entering my local ploughing match best farmed farm competition (no chance of that), it took a very bad infestation of weeds to knock yield below 2.5 tonnes an acre. Very often we edged towards three tonnes and in 1984 we even exceeded it.

That yield range provided a perfectly reasonable profit and avoided all the risks associated with break crops. Oilseed rape establishment was difficult then (even before the recent neonicotinoid insecticide ban), and varieties in those days also had an alarming habit of shedding in high winds (common on the Downs close to the sea) or heavy rain or hailstorms once the crop ripened.

Although field winter and spring beans were easier to establish, they were also notorious for being unreliable yielders. The thicker the stand of crop, the more likely it was that only the top of the stalks would provide pods. Peas were rather similar in that less growth in a dry summer could provide a higher yield and a better quality crop than in a wetter summer when there were many more pods but many of which simply rotted off. There were other, even more risky, break crop options like linseed or lupins but we avoided them as well for similar reasons.

Geoff has long gone, but I have stuck doggedly to his advice. Until now. Were he still alive I hope that even he would agree that I now have no option but to break from cereals on much of my acreage.

In some fields, the blackgrass threat is building to an ominous degree and the array of permitted herbicides to tackle it is ever more puny. I also seem to have imported an unwelcome new insect guest in one field that goes by the name of ‘zabrus’, whose larvae look like leatherjackets on steroids. These little beasts take cereal seedlings and drag them underground to eat them. The only way to rid the field of them, apparently, is to grow something other than a cereal crop. My crop consultant has therefore become ever more strident in her advice that my continuous cereals days are over.

So, as I survey the generous pile of wheat in store, I have to accept that riskier times lie ahead. Expect my columns to become even more grumpy as an old dog attempts to learn new tricks.