The First Agricultural Revolution was the transition of humans from nomadic hunting/gathering to sedentary agricultural production of domesticated plants and animals. A result of the warming period directly after an Ice Age, the first place to of recorded this Revolution was the Fertile Crescent in the Middle East.
The group that started the First Agricultural Revolution were the early members of humanity that settled in the Fertile Crescent area of the Middle East. Other groups achieved similar results later in China (unknown if independent from Fertile Crescent) and South America. The members of this group were the first to settle into a specific area of land and stay sedentary for long periods of time
The second agricultural revolution is generally said to have occurred along with the Industrial Revolution. It came about in part because of the Industrial Revolution and it helped allow the Industrial Revolution to happen.
The second agricultural revolution was based on a greater use of technology. In this revolution, farmers started to use machinery in many more aspects of agriculture. For example, they started to use machines to plant their seeds more consistently and effectively. They began to use machines to harvest their crops and to do things like separating grain from chaff. Another type of machinery that was important for this revolution was the train. Trains helped transport large amounts of farm produce from farms to cities, thus allowing farmers to profitably grow more crops. Finally, there were new farming techniques such as a greater use of fertilizers to help increase yields.
The third agricultural revolution, beginning approximately 250 years after the start of the second, has three distinctive features. The first is the removal of the lines distinguishing agriculture as primary, secondary, and tertiary activities. Farmers and agriculturists now engage one or more, including the primary activity of crop production, some sort of secondary activity such as manufacturing or processing the crops, and tertiary activities such as marketing and advertising their products through co-ops and other marketing organizations. The second distinctive feature of this agricultural revolution is more intensive mechanization biotechnology is the third. Mechanization began replacing animal and human labor in the United States during the late nineteenth century. After World War II, mechanization spread to Europe and other parts of the world. Machines have gotten larger, more powerful, and more efficient.