I hope you are right about the blackgrass, but how are you so sure? I've had some fields into 3 years of Spring crop and there is still plenty of blackgrass. The most worrying was that because my 750 drilled Spring crops went in so late (end April) due to soil conditions, I wasn't expecting any blackgrass. Unfortunately because the crops had such a short season they didn't thicken up to outcompete the blackgrass that did come and its shed as much seed as I probably got rid of in the previous Spring crops.
By spring cropping I don't mean wheats and barleys etc - will use very late drilled crops like linseed and millet that also have in crop chemistry options
3 years is a very short time in farming to sort out an issue that was decades in the making.