It is a good idea for governments to subsidize cultivating food grains. The government should make sure that people have enough foods to eat. Subsidies ensure that there will always be enough staple foods in supply to support the population. Hunger can lead to instability and revolution in a country.
I think that it makes sense to subsidize food grains. it gives incentive to American farmers to actually keep producing their crops on American soil, rather than selling out to foreign countries and importing it. I think that subsidies can be used as a way to keep the farmers going.
If you subsidize a product or a service you're ultimately paying the same amount for it - people pay lower costs in the supermarket and more in taxes. In addition, since subsidies guarantee an income for growing certain products, this ultimately leads to the planting of more of said grains - instead of other, possibly more desired.
It is not good economic policy to subsidize cultivating food grains, because allowing the market to sort out supply and demand and settle on a price is the best way to handle the grain commodity. If there are no subsidies, there will be fewer producers. This will cause prices to rise. Additionally, the future market can stabilize production for farmers, so they do not see large swings in income.
No, it is not good economic policy to subsidize cultivating food grains, because that is manipulating the free market. Without subsidies, prices will rise as there are fewer competitors in the market. There is no need to subsidize grains, because the market will regulate how many grains are produced. There are futures markets to help regulate prices for growers.