Have I Seen My Farm?

Fictional universes often feature parallel dimensions, places where people normally cannot go but that exist alongside us. The underwater world is a real life example of this, a realm of the imagination until the development of scuba and submarine technology. However an even more significant parallel dimension exists closer to home, hidden beneath our feet. The topside world we live in is one of DNA destroying ultraviolet light, corrosive oxygen and extreme fluctuations in temperature and moisture that the majority of species on the planet refuse to tolerate. Instead they prefer to live underground. Even plants, the quintessential worshippers of the sun, have about half of their biomass hidden away from our inquisitive eyes. Humans are primarily visual creatures and yet the better half of the landscape is invisible to us, a plain fact that should be kept in mind since it impacts many aspects of managing a farm.

The first major consideration is that the soil beneath our feet is an even more complex and varied landscape than the one above. The mineral composition of the soil also varies dramatically at different depths and locations even in apparently uniform flat places, rendering lab tests of surface soil at best incomplete, at worst misleading. . This can result in one species of plant simply refusing to grow in a particular spot, a reflection of a geological iceberg floating just under the surface. I often see this when I plant long rows of a species across the landscape, where they start out growing vigorously, then a bit further along grow poorly, then a little further refuse to grow even with repeated plantings.

While we can assess surface topography to manage surface water flow with structures like swales and dams the underground is comprised of many varying layers, each with their own topography and permeability that influences how ground water flows through it. This leads to inescapable variations in soil moisture patterns over time, creating spots that are more consistently dry or wet, sometimes in complete opposition to what is predicted based on surface features. In a functional ecosystem the majority of the water should move through the landscape as ground water, provided soil porosity is sufficient to absorb the majority of rainfall without run off. The use of heavy machinery is astonishingly effective at destroying this essential sponginess of living soil, often at surprising depths even after only a couple of passes. This can sometimes be observed as persistent lack of growth or species composition change around places where vehicles once moved. I once read an account of how the first wagons to travel inland in Australia left deep ruts in the spongy soil as they travelled, which were still visible decades later despite no subsequent carts using the route.

Another place this blind spot shows up is in assessing the progress of plants as they grow. Often I plant a tree and it will sit there looking slightly miserable for years. If I simply relied on my vision I would conclude the plant is not growing since it has barely increased in height. Often though these plants surprise me by suddenly putting on a huge amount of top growth after years of superficial stagnation. The whole time the plant was expanding its root system, unseen by me. Only once the plant had a secure foundation did it feel confident in allowing its above ground parts to expand. This balance of leaves and roots is a critical calculation a plant must make. Too much top growth means the roots cannot supply sufficient water during dry spells, leading to wilting or even death. Too much root growth and the plant risks another competitor growing first and claiming access to the sunlight.

This inability to assess a root system without destroying the plant also shows up in the consequences of growing plants in pots. The above ground parts of a plant have a carefully optimised growing structure that balances the requirements of mechanical strength and efficiency of light capture among other factors. If a half grown tree is severely pruned it will usually grow back, but the structure is permanently compromised, leading to a legacy of weakness. The same is true for the unseen underground parts of a plant. When a tree is grown in a pot its root system is usually distorted. The longer the tree is in a pot the more severe this becomes. Even growing in the new “root pruning” pots doesn’t completely fix this problem. As a result the root system of a mature tree that was transplanted from a pot at an advanced size never achieves the structural strength and water harvesting efficiency of a direct seeded tree. As a result such trees are more likely to die in droughts or be blown over by storms than those which express the full potential of their root system. Those planted out at a small size seem to have lesser problems, much like a very young tree that is pruned harshly can recover its core structural elements.

One approach to this reality would be to invest in even more complex technology that can scan underground structures with remote sensing, and soil tests that analyse samples all across the landscape at multiple different depths. Gathering an ever increasing pile of data (at ever mounting expense) allows ever more sophisticated three dimensional plan to be drawn up to be imposed upon the landscape. Maybe rather than just shifting soil on the surface to make swales we could peel the Earth down to its bedrock and reconstruct everything to our designs. That way you could make sure each plant was put in the precise perfect location.

Or you could solve the way nature does it. When a single tree produces tens of thousands of seeds in its lifetime it typically only sees a tiny handful even get past seedling stage. The majority die because they land in places that could never support them, for a large number of reasons. It might seem wasteful for a tree to sacrifice almost all of its offspring (maybe trees think the time we spend drawing up fanciful plans is wasteful as well). But this is the best strategy in a world bristling with constantly changing variables. Instead of basing success on understanding and controlling everything plants simply buy a million lottery tickets and don’t even try to guess the “correct” numbers. A farmer can replicate this by putting as many propagating units (seeds, cuttings or small transplants) in as many different locations as possible, of as many different species as possible. You can reduce wasted energy by planting three of something in an area, then observing if they respond well, before deciding if you should plant more. If they don’t make it then you don’t need to know why they died, or try to change the space to suit that first species. Try ten other species instead. That way you could allow plants to select themselves, regardless of whether a particular spot was rocky or soggy, high in calcium or low in boron. You will know success when you see it and that is all you need to know.

Soil profile from our neighbor’s bore hole on the creek flats. Everything from light orange silty clay (upper left), through to pure white kaolin clay (lower left) then transitioning to what looks like grey crusher dust road base (bottom right). All the minerals you could ever want, provided you can get them to the surface.

A great example of a compromised root system. This is a native sweet potato from the deep sandy soils far inland from here, with roots that go straight down many meters. Even in the biggest pot I could find they went down and made a sharp left. Even carefully transplanted into an ideal habitat this plant could never cope with a crippled root system.

Misty mornings make the whole world look mysterious, cloaked and just out of view. What lies forever hidden, deep beneath in the beating heart of the earth?