The heavy plough needs to be invented to allow the more intensive settlement of Britain, Germany, etc. If its invented during the Early Empire, then it would allow the continued territorial expansion of the Roman Empire across the Northern European Plain. In any case, its invention and spread before the 3rd century would also help to insulate the Roman population against the Crisis of the 3rd Century (population collapse and subsequent political chaos and end of the Principate/beginning of the Dominate).
I personally think that the population boost that would be gained from this invention would help to keep the Roman Empire going, mainly through expanding and more intensively settling those areas that consider themselves "Roman".
If the population collapse that set off the Crisis of the 3rd Century can be overcome, then the Empire can probably continue. Greater manpower from Gaul, Germany and Britain will allow those areas to better fund and man their own defense, while contributing greater trade and tax revenue to the Empire.
The invention might also allow the Empire to externally settle some of the tribes that attempted to invade the Empire in the 3rd century. With the ability to effectively farm areas that with OTL Roman technology were marginal areas that later in OTL became Europe's bread basket, Poland(-Lithuania) and Russia, would become more important. Perhaps instead of Poland we have Gothia?
I personally think that the population boost that would be gained from this invention would help to keep the Roman Empire going, mainly through expanding and more intensively settling those areas that consider themselves "Roman".
If the population collapse that set off the Crisis of the 3rd Century can be overcome, then the Empire can probably continue. Greater manpower from Gaul, Germany and Britain will allow those areas to better fund and man their own defense, while contributing greater trade and tax revenue to the Empire.
The invention might also allow the Empire to externally settle some of the tribes that attempted to invade the Empire in the 3rd century. With the ability to effectively farm areas that with OTL Roman technology were marginal areas that later in OTL became Europe's bread basket, Poland(-Lithuania) and Russia, would become more important. Perhaps instead of Poland we have Gothia?