For more and more people today, shopping for food involves a stop at the farmers market or the organic produce section of the local grocery store. As a result, sales of organic food rose a healthy 10.2 percent in 2012 and captured 4.3 percent of total food sales, according to the Organic Trade Association. Organic food sales generated a healthy $29 billion last year. That's not bad for an industry that is fairly new: the USDA didn't approve national standards for organic food until 2002.

So where did this engine of healthy food and economic growth come from? Although many people think the idea for organic farming harkens back to a simpler time before industrial agriculture, the truth is that we owe many of the ideas about organics to a few people in the 20th century.

The most notable of these is Walter Ernest Christopher James, better known by his title, Lord Northbourne, who first used the term "organic farming" in his 1940 book "Look to the Land," which is still in print more than seven decades later. Lord Northbourne's book posits that "the very large increase in the use of [artificial chemicals] which has taken place during this century has coincided with an almost equally rapid fall in real fertility." He predicted that "the results of attempting to substitute chemical farming for organic farming will very probably prove farm more deleterious than has yet become clear" and called for a return to a system of looking at the land as a living organism.

Lord Northbourne was not alone. The same year that he published "Look to the Land," British botanist Sir Albert Howard published his classic book, "An Agricultural Testament." Based on his decades of work documenting traditional farmers in India, the book tackles nature-driven principles such as soil fertility and composting instead of the chemical methods that were becoming standard at the time. He called this the Indore method, "the manufacture of humus from vegetable and animal wastes" to improve soil fertility. Inspired by traditional European and Asian farming models, humus farming used a combination of composting, crop rotation, and soil additions — such as manure, lime and other natural rocks — to manage the pH of soil.

Howard's book would become the more influential of the two 1940 volumes. Based on his work, Lady Eve Balfour conducted the first scientific study to compare the efficacy of organic vs. chemical farming. Her results were published in yet another influential book, "The Living Soil," which was published in 1943. Three years later she would start the Soil Association, probably the first group to advocate for organic farming.

The concepts of organic farming grew for the next few decades but got their next big push in 1962 when Rachel Carson published her groundbreaking book, "Silent Spring," which famously documented the effects of the pesticide DDT on the natural environment. Embraced by the growing environmental and counter-culture movements, Carson's book became a call to action to support organic foods and to avoid synthetic chemicals.

Unfortunately, the earliest proponents of the "back to the land" movement of that time forgot or ignored the lessons of Howard, Balfour and Northbourne. According to "A Brief History and Philosophy of Organic Agriculture" by George Keupper (pdf), "many novices failed to understand that growing quality food without pesticides or synthetic fertilizers would not work very well without the regenerative practices of the traditional organic method." This resulted in what was called "organic by neglect" and produced some pretty unpalatable produce.

Despite this setback, organic produce continued to make progress. The first regional organic standards were developed in the 1970s and 1980s, although each had its own guidelines that provided little consistency for customers. The Alar scare of the 1980s finally led to the first national organics law — the Organic Foods Production Act of 1990 — which in turn, eventually, led to the national standards that were finally published in 2002.

It took a long time, but organic foods and farming are now here to stay, and they have been standardized in a way that protects both food and consumers. For that, we can thank Lord Northbourne, Sir Albert Howard, Lady Eve Balfour and those who followed in their important and world-changing footsteps.