By Peter Bane

Climate change has made farming a more challenging pursuit than ever before as heating of the atmosphere drives drought, flood, and storms beyond all historic norms.

Two broad strategies must become part of every farmer’s toolkit: trees and water catchment. The latter is more immediate, and I address strategies for it below. 

Trees provide long-term adaptation and also mitigate against the root causes of climate change, which is driven by disruptions to the hydrologic cycle caused by changes in land use, in particular the removal of vegetation from vast areas. These hydrologic disruptions are exacerbated by the release of carbon stored in forests and soils into the atmosphere as CO2, where it joins fossil carbon from the industrial use of coal, oil, and gas.

Because rain and snowfall are now more intense and less regular, we have to catch moisture when it falls, and hold it on the land. This both increases water supply and restores balance to the hydrologic cycle at a local scale. 

Start at the top

On a small scale, every roof is a water collection system if it has gutters. This high-quality runoff can be directed to tanks, and from tanks into ponds for use and temporary storage. 

Especially in flat Midwestern landscapes, the house or barn roof is often the highest point in the local catchment. Intercepting water as it comes off the gutters allows us to direct it to nearby tanks, where it can be stored for high-value uses such as domestic water and drip irrigation. Avoid pumping when you can: place your tanks not far from the building, but on the highest ground available. Take the overflow to ponds if you can. This will preserve the fluid resource for pumped irrigation, firefighting, stock watering, aquaculture, or recreation. At a minimum, create depressions or swales where overflow can be safely absorbed into the ground.

Control the spread

A corollary of catching and storing water above ground is the need to distribute it. Every household and farmstead needs a reticulated water system. Ideally, this can switch between sources such as the pumped water from wells and the tank water stored high enough to flow by gravity. The system should have valves that enable this and that separate sections of the system to allow for repair. The irrigation system should work in all seasons, which means it must be protected from freezing, thus with mains laid below the frost line, and accessed by freeze-proof, self-draining yard hydrants or an equivalent.

Tanks can be of various forms. Rain barrels are easy to install but hold very little water. A more useful option is the IBC tote, a polyethylene tank between 260-330 gal. capacity in a metal cage with a constructed platform base. Ganged and protected by a hoophouse, these can form the basis for winter cultivation and year-round water in moderate climates. Their thermal mass stabilizes temperatures in a greenhouse or polytunnel. Uncaged polyethylene cylinder tanks and fiberglass and used stainless dairy tanks are available in larger sizes, though site-built ferrocement tanks, ranging from 1,500 to 20,000 gallons, are the best solution for large tanks. Art Ludwig’s Water Storage provides a basic guide (Oasis Publications, Sta. Barbara, CA). Always place large tanks in a location where their thermal mass, screening, and windbreak functions can benefit adjacent plants, animals, or structures.

Enrich the soil

I have mentioned three forms of water storage: tanks, ponds, and soil, in the order of the quality of water they hold. Of these, soil is the greatest and the cheapest storage.

Soil’s capacity to store water is a direct function of its organic matter content. If your soil organic matter (SOM) averages 2.5%, you have very little resilience to flood or drought, but if it is 7-8%, you can handle most rain or drought events, even in a disturbed climate. 

Importantly, SOM can only be increased with water because it accumulates from the growth and death of plant roots and decomposition by microbes, both of which depend on soil moisture. It is urgent, therefore, to begin building SOM when your climate still has available moisture, whether this is seasonally or over the long term. 

Compost and cover crops can build SOM, as can manuring, intensive rotational grazing by livestock, and chop-and-drop or coppice management of trees and shrubs. These processes contribute to soil climaxes, or the growing, death, and decomposition of organic matter above and below the ground. Indispensable to success is keeping the soil covered at all times. Tillage, which introduces oxygen to the soil, is the enemy of SOM, causing it to oxidize or burn up, returning carbon to the atmosphere.

A limited exception to the need for moisture and cropping to build water-holding capacity is, ironically, the use of fire to create biochar. This is charcoal derived from plant residues which are heated in the absence of oxygen, a process called pyrolysis. Biochar is a special form of carbon, riddled with microscopic pores because charring preserves the original cell structure of the plant material. These pores hold water, microbes, and nutrient at least as well as humus or other forms of SOM, but biochar is durable over centuries as microbes cannot easily break its chemical bonds. 

Farming a cold, wet desert by the Lake

I farm in western lower Michigan on soils of nearly pure sand. Though we have minimally adequate rainfall, moisture is erratic in summer with large, infrequent downpours which drain away rapidly, punctuated by light rains that do little to wet the soil. 

For our farm, SOM is a matter of life or death. The only way to grow crop plants in this climate and soil regime is to hold water in the surface layers of soil where most annual and small plant roots proliferate. To do this, we need mulch from woodchip or straw. Together with poultry on range, our trees are the main source of fertility. They can send roots down to the shallow water table, and thus endure the swings of surface moisture. The deep roots of prairie plants can also access this ground water, but garden vegetables and annual crops cannot. They need irrigation.

Patterns connect elements in flow

The culminating strategy that integrates these elements of soil fertility and water management into a workable system is patterning. Patterns are both spatial and temporal. Cultivation and the movement of animals or machinery should always be done on contour to harvest water from surface runoff while reducing erosion. We plant our trees in rows separated by alleys of grass and forbs (alleycropping, a form of agroforestry). This gives us the beneficial edge effect between different ecosystems, and places the woody material where it can easily improve the land with least effort. 

Multiple functions

Our alley pastures provide grazing for animals, supplemented by forage and fodder harvested from the trees. The trees bring up moisture, provide shade to cool the soil surface, and offer shelter against our often harsh winds. Some of the tree species fix nitrogen at their roots, so that when we coppice them to feed animals or for mulch, they release that nitrogen to surrounding plants. The trees and shrubs also attract and shelter birds and insects among other small creatures, whose frass and droppings enrich the whole. The alleys between the trees and shrubs, when grazed by livestock, contribute a drench of manure tea to the roots of the trees with every rain or irrigation.

Most farms have a woodlot, but trees can make a much greater contribution to farm productivity and health if they are distributed throughout the growing spaces as windbreaks, hedgerows, bio-islands sheltering beneficial insects, and sources of food, fodder, fuel, and poles.

Trees are also our main ally in combatting climate change. They cycle moisture into the atmosphere, and through transpiration, they release absorbed solar energy without heating the land surface. A cooler soil (covered with vegetation, actively cooled by trees) radiates less solar energy to the atmosphere, lowering the planet’s temperature. Heat islands are not only an urban phenomenon; they occur over bare soil on farms as well.

The solutions for planetary health are the same ones that enrich the land. Sky and soil are one system. Our job is to maintain the balance. Catch, store, and circulate water and carbon between sky and soil, using trees, animals, and diverse plants. Pattern the land and the crops to harvest water and deepen soil. Build a culture from these things. Tell their stories. Celebrate fertility and abundance. Share with all of life.

Peter Bane is the Executive Director of Permaculture Institute of North America (PINA.in), and the author of The Permaculture Handbook: Garden Farming for Town and Country (permaculturehandbook.com). He is a long-time teacher, designer, publisher, and author, and now farms 18 acres with his family in western Lower Michigan.