Positive Health Online

How Soil Organisms Can Reduce Agriculture’s Emissions

My last article for Positive Health PH Online concerned how we can re-mineralize soil to produce better quality food.

www.positivehealth.com/article/environmental/damaged-soils-human-health-and-how-to-improve-the-quality-of-food

This time I want to focus on how we can further improve both crops and the environment by restoring full vigour to the countless life forms that should be present in a living soil. I say “should be” because they rarely are these days.

Modern agriculture is for the most part predicated on the simplistic use of nitrogen, phosphorus and potassium fertilisers (just three of the ninety-odd soil minerals) as plant growth stimuli, backed up by a vast array of pesticides, herbicides, fungicides and other toxins to deal with the imbalances that result from the consequent destruction of the soil food web. This crude approach to food production completely by-passes the benefits to be had by harnessing soil life whilst simultaneously mining soil reserves.

Life in the Soil Ecosystem

One square metre of a healthy soil contains countless more billions of creatures than there are people on the planet. Just one teaspoonful contains between 100 million and 1 billion bacteria alone, in weight equating to 5 cows per hectare. Starting with the smallest organisms, it is worth taking a look at what goes on under our feet.

Bacteria

The best known are the nitrogen fixers that create nodules on the roots of legumes, providing stores of nitrogen for both plant and soil. Synthetic nitrogen costs £350-400 per tonne; the bacteria work for nothing! Other species are decomposers of plant material, enriching the soil and emitting that wonderful fresh earth smell. A species called Pseudomonas flouorescens specializes in killing pathogenic fungi, thus improving plant growth and health. Not all are helpful, there are also de-nitrifiers that flourish in anaerobic conditions and take plant available nitrogen and convert it to undesirable nitrous oxide, a major greenhouse gas. The moral here is to keep soil from becoming anaerobic.

Fungi

There are many different species comprising three main groups. Two of these, the decomposers and the symbiotic, are very beneficial; the third group, the parasitic and the pathogenic, are the ones we try to kill.

The best known beneficials are mycorrhizae, which greatly increase a plant’s effective root area by connecting roots with an underground spread of mycelium and by transferring minerals to the plant in return for molecules of starch and sugar.

The most notorious pathogenic fungi include Candida; there are many aflatoxins and mycotoxins, such as Ergot and Aspergillus, which are both parasitic and pathogenic. Some of these pathogens are responsible for serious crop losses, yet in a balanced soil they are preyed upon by a variety of other fungi, which can level the playing field.

Protozoa

These are larger, mobile single cell organisms that feed on bacteria; the largest of them can each consume many thousands per day. This process releases plant-available nitrogen in the form of ammonia and helps regulate the bacteria population.

Nematodes

The majority of nematode species are beneficial, enriching the soil with recycled nutrients and balancing the numbers of competing species. Most are millimetre sized and eat bacteria, fungi, protozoa and other nematodes, including the parasitic variety that feed on crop roots and drive farmers to drink.

Arthropods

These are creatures that are generally large enough for us to see. They range in size from mites to centipedes, with springtails, beetles and other insects in between. Some arthropods are known to damage crops, but most are beneficial in many ways, as they improve soil texture, aeration, water retention and quality. In short, they are essential inhabitants of a healthy soil.

Earthworms

Finally, we come to the one member of the soil community familiar to the general public - the earthworm. There are again thousands of species of earthworm comprising three categories. There are those that live in on the surface trash, those that burrow horizontally in the upper soil layers, and those that have vertical burrows that go deep into the soil. These creatures are almost entirely beneficial, but on tilled soil are decimated by the plough, by raw slurry, by badgers, birds, moles, shrews and foxes (and hedgehogs, where badgers haven’t eaten them all). In a decent, living soil earthworms can produce tons of nutrient-rich wormcast per acre, per year.

If you have managed to read this far, you may have guessed where I am going with this.

If we fully understood the inter-relationships and necessary balance between all the myriads of soil life forms, we could probably produce large, nutritious quantities of any suitable crop with minimum financial input. Unfortunately, we have been looking the other way for 70 years or so. Modern farming systems tend to treat the soil the way World War 1 treated the landscape and protagonists in northern France. It is a scorched earth system and last year’s awful summer revealed just how fragile it is.

We slice and dice, spray, scorch and burn with sledgehammer chemicals that compromise our health, let alone the collateral damage to plants and creatures they are not aimed at. All too often, all that is left is a chemical substrate, almost devoid of organic matter and virtually lifeless.

At this point, having ejected the baby with the proverbial bathwater, we have no option but to stick with chemical farming, because it is now the only way to get any acceptable yield (and is better not to look closely at the nutritional quality achieved).

A Better Future?

Possibly, but the trouble is, as yet we know little about these teeming populations under our feet, how they interact, what constitutes the correct ratio of species, how populations vary dependent on what crop is being grown and how climate and differing soil types affect all these variables.

More research into these matters is long overdue and our focus as a company increasingly includes remedial biology and how we exploit the obvious benefits to develop a truly sustainable agriculture. At present the manufacture, transport and use of fertilisers accounts for 47% of the energy profile of UK farming. That is not sustainable and is a profligate use of finite resources.