The physiology of plants has been of great interest and importance to humans for thousands of years. When ancient humans discovered that they could cultivate certain plants, such as rich, wheat, and corn, they began to protect and care for their crops. Of particular importance to humans was the ability to encourage plants to grow faster, stay healthier, and produce more fruit and seeds. To accomplish this, humans began to learn about plant physiology.
Fertilizer, usually animal manure, was added to the soil to provide nutrients, particularly nitrates and phosphates, for the plants. Because water was necessary for crops, farms were typically built near sources of rivers and lakes. Later, irrigation ditches were built to help disperse the water throughout the fields.
Since those ancient days, farming has become more sophisticated. Irrigation is still important. Fertilizers are usually produced in factories and contain just the right balance of micro and macronutrients. Some crops will have growth hormones sprayed on them. And recently some crops are being genetically engineered to produce larger and healthier fruit.