Huh? No, the net effect is higher overall yields. Where do you think the depressed prices come from? Increased supply without higher demand due to a higher incentive to produce than the market alone would provide, resulting in overproduction.
Of course, it depends to a certain extent on how the subsidies are structured. If the subsidy is a straight handout, then you’re right, the incentive to maximize yields is lower. If the subsidy is for acres seeded, then the incentive is to maximize seeded acreage, though perhaps not aim at maximizing yield (this will of course depend on the relation between grain prices, input costs, and the expected yield gains from higher inputs - it’s entirely possible, and even likely, that there will still be incentive to maximize yields). If the subsidy is a direct export subsidy, then the incentive is to maximize yield plain and simple.
My theory as to what Sam is trying to get at is that there are acres seeded that perhaps shouldn’t be because their potential yield is insufficient to make cultivating them profitable absent subsidies for either keeping the land in cultivation or for raising the specific crop on them, though frankly I still don’t see how his initial statement can be read that way. The point may well be correct. There’s a lot of pretty marginal land in southwest Sask and southern Alberta that certainly isn’t profitable to grow cereal grains on (at least, not at current commodity prices), but which might support ranching. That’s a bit of an esoteric point, though. The land in question wasn’t broken under the auspices of massive agricultural subsidies, but rather during the homesteading era. Well, I guess you might call homesteading a subsidy, what with all the land given away, however, the goal of homesteading wasn’t increased agricultural production, but rather getting people to actually move here. The thing is, reverting cropland back to grassland is rather expensive. Grass seed costs a hell of a lot more than cereal grain seed, or even seed for oilseeds and pulse crops. And it can be difficult to get grass to catch - it requires more rain at more specific times in order to establish itself, and in the absence of such rain, one might have put all that expensive seed in the ground for no return whatsoever. Hence, the short term calculation between crops and grass might come out in favour of crops even if the long term comes out in favour of grass. And short term is what matters if the bank is on your ass about defaulted land payments. It’s a bit odd to oppose ag subsidies because they favour cereal grain production + feedlots over grass-fed beef, though.
Or maybe he just thinks the subsidies encourage continuous cropping, which he thinks to be poor farming technique. If that’s what he’s trying to get at, he’s simply operating on the basis of an obsolete understanding of agriculture. Forgiveable, but not very helpful.