"SimCity 4" has a special zoning tool for agriculture. The agriculture zone is low density industrial and require only power and road connections to grow. Before the "Rush Hour" expansion pack, farms did not produce money for the city, only jobs. By using the special zone for farms, you do not have worry about other industries buying out the zones and losing the farms. You can keep your realistic country towns
Farms do not provide a lot of positives for your city. They do however, with "Rush Hour," earn money for the city and provide a few low paying jobs. The biggest positive is the Farmer's Market and State Fair rewards. The Farmer's Market reward provides a demand cap relief of 20,000 RS and 150,000 RSS. While you can bulldoze your farms, and still keep the Farmer's Market, it will not be as effective.
Farms & Pollution
Farms produce a lot of water pollution.Once water pollution arrives, you need to plant trees to help offsite the effects of pollution. Farms near water will make the water turn brown. It's important to note that agriculture zones are not required for your city to grow.