I think there is a tradeoff between increasing the welfare of farmed and soil animals due to the cost of feed. Welfare reforms increasing the amount of feed needed per kg of food lead to more agricultural-land-years, and therefore increase the welfare of soil animals (for my best guess that they have negative lives). However, increasing the amount of feed per kg of food also implies a higher cost per kg of food, which contributes towards those welfare reforms being a harder sell, and increasing the welfare of farmed animals less cost-effectively.
Here is an illustration of the above for welfare reforms improving the conditions of chickens. I estimate broiler welfare corporate campaigns increase the welfare of chickens, and soil ants, termites, springtails, mites, and nematodes 5.72 (= 4.60*10^3/​804) times as cost-effectively as cage-free corporate campaigns, which is practically fully explained by broiler welfare corporate campaigns increasing agricultural-land-years 5.73 (= 93.9/​16.4) times as cost-effectively as cage-free corporate campaigns. However, I estimate broiler welfare corporate campaigns increase the welfare of chickens 36.4 % (= 0.255/​0.701) as cost-effectively as cage-free corporate campaigns. This is explained by broiler welfare corporate campaigns increasing the cost per food-kg significantly more than cage-free corporate campaigns, which I suspect is largely explained by the former increasing feed much more. I estimate broiler welfare reforms increase the feed-kg per food-kg 12.7 (= 0.919/​0.0726) times as much as cage-free reforms.
I think there is a tradeoff between increasing the welfare of farmed and soil animals due to the cost of feed. Welfare reforms increasing the amount of feed needed per kg of food lead to more agricultural-land-years, and therefore increase the welfare of soil animals (for my best guess that they have negative lives). However, increasing the amount of feed per kg of food also implies a higher cost per kg of food, which contributes towards those welfare reforms being a harder sell, and increasing the welfare of farmed animals less cost-effectively.
Here is an illustration of the above for welfare reforms improving the conditions of chickens. I estimate broiler welfare corporate campaigns increase the welfare of chickens, and soil ants, termites, springtails, mites, and nematodes 5.72 (= 4.60*10^3/​804) times as cost-effectively as cage-free corporate campaigns, which is practically fully explained by broiler welfare corporate campaigns increasing agricultural-land-years 5.73 (= 93.9/​16.4) times as cost-effectively as cage-free corporate campaigns. However, I estimate broiler welfare corporate campaigns increase the welfare of chickens 36.4 % (= 0.255/​0.701) as cost-effectively as cage-free corporate campaigns. This is explained by broiler welfare corporate campaigns increasing the cost per food-kg significantly more than cage-free corporate campaigns, which I suspect is largely explained by the former increasing feed much more. I estimate broiler welfare reforms increase the feed-kg per food-kg 12.7 (= 0.919/​0.0726) times as much as cage-free reforms.