1. Farmers used to have 100-200 acres apiece. At that point you can feed a family even with very low yields. There were few (if any) large-scale farming operations for them to buy from, anyway.
2. Each generation, the farmer would divide the land up amongst his sons.
3. Fast-forward to today, farmers have more like 2 acres, and with traditional farming techniques don't have enough yield to feed their families.
4. They make up the difference with cattle, chickens, beans, odd jobs - or don't make up the difference, as malnutrition and starvation are a constant problem. But if they make enough money, there is a national maize market to buy from, which previously there wasn't. Hence, they're net maize consumers.
"subsistence farmers are net consumers of their staple crop. In order to survive, the poor diversify across a variety of agricultural products"
I don't understand the downvotes for the parent. They are growing other products, or have cash from other activities, and use this to buy the staple they can't grow. If price of staple rises and price of other products and services does not, they can't afford to do this. The beneficiaries are large industrial farmers of the staple. Did I miss something?
If there is in fact a problem (and I do question its existence), I believe lukasb is looking for it in the wrong place.