Ditch the Plow

Ditch the Plow, Cover Up and Grow Diversity for a Sustainable Future

by John M Repp

A review of Growing A Revolution: Bringing our Soil Back to Life David Montgomery. (Norton, 2017)

Montgomery co-wrote The Hidden Half of Nature that explains how microbes in our lower gut and in topsoil make life and health possible. Growing A Revolution tells the story of a few farmers around the world that are adopting new practices that protect and enhance the life in the soil on land where humans farm or graze animals. Widespread adoption of these practices will keep the soil sustainable while maintaining crop yield for a better future.

Montgomery sees a pattern in the history of many civilizations. They started farming in the river valleys and as they prospered and grew, they moved up the hills. Their farming practices caused erosion and eventually they wore out or lost most of the topsoil. After that, the civilizations collapsed. There were exceptions like Egypt and China where the river valleys were large and periodic flooding brought in new fertility. Montgomery cites the long past of Greece as an example of the pattern he sees. First Bronze Age Greece recorded by Homer, followed by a dark age, then the ancient Greece of Plato and Aristotle, followed by another dark age, and finally, modern Greece. There was a two-thousand-year cycle. With ancient farming practices it took about a thousand years to wear out the soil, and a thousand years for nature to build fertility back into land not used by humans.

After World War II, agriculture in the developed countries became ever more mechanized and dependent on chemical fertilizers, herbicides and pesticides. Monoculture and ending of the ancient practice of mixed farming of plants and animals completed what Montgomery calls the third revolution. The yields were spectacular at first and these methods spread. More recently however it has been ever costlier to maintain yields using these methods because of the need to use ever more agrochemicals and oil that are becoming more expensive. Lately, consumers have been demanding organically grown food, called here the fourth revolution. Montgomery is advocating a fifth revolution based on soil biology rather than soil chemistry that underpinned the third revolution.

The three principles of the fifth revolution are: “1) Open up the soil only enough to plant a seed – minimally disturb the soil. 2) Make sure the ground is covered with prior crop residue at planting, and use cover crops to build biomass and soil organic matter. 3) Introduce diversity to the fields through rotations and intercropping”. (p. 129) Montgomery traveled to farms all over the world to see how these principles were applied to different climates and soils.

Looking through the lens of soil biology makes the first principle more understandable. Tilling breaks up mycorrhizal fungi strands, that together with certain bacteria, feed the plant phosphorus. Plant roots exude sugars that nourish the microbial and fungal life that naturally fertilize the plant. It is the sticky plant root exudates that gives soil its structure, making it crumbly, with aggregates as well as tiny opening spaces. Tilling breaks the capillary pores preventing subsoil water from rising to the surface, and allows rain water to be absorbed quickly. With no-till and the other two principles, crops are more tolerant of heavy rains and droughts.

The amount of organic material and carbon in soil is easily measured. The total amount of carbon in the soil over the entire world is estimated to be twice as much as the carbon in the atmosphere. Using the three principles, soil carbon can be built up quickly. Montgomery challenges the old idea that it takes a thousand years to build an inch of topsoil. Using all three principles together which he names “conservation agriculture”, farmers can build up healthy soil in decades. If conservation agriculture were practiced world-wide, up-to-a third of the carbon from global fossil fuel emissions could be sequestered in the soil. (p.126) That would go a long way towards mitigating global warming.

Planting cover crops right after harvest is part of the practice. On some farms a substantial number of different cover crops are planted at the same time. In the spring some farmers crush the cover crops as the next crop is planted. A good rotation is more complex than the current rotation of corn followed by soy followed by corn, used all over the U.S. middle west. If the rotation is too regular some pests will adapt.

The book has a chapter on grazing. Mimicking what wild animals do to protect themselves from predators, the large herd is fenced into a few acres to make them graze close to each other. The herd is moved every four hours and will not return to the same spot for a year. A rancher who did this restored his soil to its native carbon content while the sugar and protein content of his grass increased. His fields could absorb rainfall up to 16 inches an hour while his neighbor’s fields absorb less than an inch an hour. (p.191)

The City of Tacoma transforms its sewage into TAGRO, a microbial digested fertilizer very popular with the city’s gardeners. Raw sewage is screened and skimmed, then heated up to kill off microorganisms and pathogens. Then oxygen is pumped in to power the growth of microbes that aerobically digest the sludge. Then methane digesters feed anaerobic bacteria that gorge of the bodies of their dead brethren. TAGRO is safe and given away to community gardens and sold out every spring to the public. Montgomery writes that we need to see wastewater treatment plants as resource recovery plants.

Montgomery writes that it is conventional thinking and powerful commercial interests that are holding back a wider adaptation of conservation agriculture. All the government subsidies are backward. Except for a several years transition, conservation agriculture is more profitable than the method it is replacing, and requires less work. He thinks financially backstopping farmers during the transition is a good idea. Some of the other reforms he suggests are: having commodity support programs require cover crops and diverse rotations, paying farmers to sequester carbon, encouraging the reintegration of crop and livestock production, adopting soil-safe certification programs, and establishing regional demonstration farms.

This is a deeply hopeful book that can help overcome the gloom that too many good people are experiencing after Trump was inaugurated.