Breaking it down


Excerpt from Chapter 8 “For the love of soil”, by Nicole Masters

In a world devoid of its army of decomposers, we would rapidly be overcome by debris and despair. Microscopic bacteria, fungi, protists and insects of every size are the critical clean-up crew, digesting organic materials and keeping our world turning. They have an extraordinary ability to break down even the most resistant, radioactive and toxic of materials, transforming them into bio-friendly foods for other organisms. It is essential that decomposition cycles on your land are performing well. Without good decomposition, nutrient cycles and profitability will grind to a nasty, stomach churning halt. This is the fourth place to look to in our triage. Decomposition is the core of your soil’s digestive function. Does your soil have indigestion, gas, constipation or diarrhea?

Across the world, cropping farms are now stalling under the weight of stubble that just won’t break down, often under the chemical fixes prescribed to the no-till generation. It’s becoming common, to find stubble remaining after three or even four years following harvest. In many cropping regions, producers have resorted to burning this oxidized material, as even a starving sheep won’t stomach it. A rancher once showed me photographs of their monitoring transect; in every photo for four consecutive years, the same cow pat featured center stage. These are the landscapes of constipation.

I love the statement: “Bet you can’t solve this one.” Not only does it get my gung-ho competitive juices flowing, but it also means I might be about to learn something new, or potentially make the difference to a farm or ranch. A few years ago, while on a Northern Montana ranch, I had just this statement posed. Their irrigated fields were full of humps and hollows. When flooded, the low points dried up and turned brown, while the higher areas were lush and green. Very cryptic, areas which should be moist and green were dead. A quick dig revealed over 7 inches of thatch in the low points.

Thatch is the result of a build-up of organic material around the base of living plants. This layer forms when plant materials accumulate faster than microbes can break them down. There are some plant species which naturally form thatch, such as Smooth bromegrass (Bromus ineris Leyss) and Kentucky bluegrass (Poa pratenis). Thatch is distinct from peat or muskeg soils, which naturally arise when organic materials accumulate in anaerobic, boggy, wet and acidic environments. Conditions for thatch formation, can include poor microbial activity, low pH or alkali soils, environmental factors and poor management. Practices such as heavy nitrogen applications, pesticides, compaction and/or over-watering can all contribute to thatch formation. Rather than growing roots deep into the soil, new roots start to grow into the thatch layer. When conditions turn hot and dry, the shallow-rooted plants struggle to survive.

Adaptive Multi-Paddock (AMP) and other holistic grazing practices place a strong emphasis on building up leaf litter. In long season, temperate climates, when using these grazing techniques, the litter won’t build up; worms, insects and microbiology actively break the grass materials down before the next rotation. This concept of litter was developed in brittle environments that have bare ground. Here, it is essential to build litter or some kind of ground cover to protect soil surfaces from wind, sun and destructive raindrops. In less brittle environments, this service is provided by a green living plant.

There are six major ingredients required for microbial digestion: air, water, sugar, calcium and a little phosphorus and nitrogen for energy. With compaction, low Brix, poor calcium and low biological activity, the soil-gut digestive system shuts down. Through building our soil-gut health programme we, can restore digestion. For cropping and horticulture, we can kick-start digestion, using inputs and on rangeland and extensive stations, we can optimise decomposition through livestock management.

Good airflow will ensure anaerobic digestion is avoided. Without oxygen, the anaerobic bacteria move in, releasing volatile organic compounds (VOC) as they feed. Like a seedy drug den on the wrong side of town, these bacteria start to push their fermented and pickled by-products which include alcohols, formaldehydes, methane, carboxylic acids, esters, ketones, sulphides, terpenes and other organic acids. Your nose will tell you when many of these microbes are at work, as they releasing a ‘farty’, rotten egg (sulphur) and ammonia smells (nitrogen), as well as carbon dioxide and methane (more carbon).[i] These smells are a good indicator that you’re losing your valuable nutrients, carbon and beneficial microbes. The foul stench of hydrogen sulfide produced in waterlogged conditions, leads to a variety of chemical reactions which produce metal sulfides. These include the insoluble manganese, which leave black flecks in soil and the ferrous sulphides which create the dark black of brown sludge in wetlands. As the waters recede, metals, such as iron sulfides, react and become iron oxides, literally rust, giving soil, distinctorange rusty mottles. If soils are anaerobic for longer periods of time, they give rise to the gleyed soils, with their blue and grey mottles. Some VOC are visible to the naked eye. In days gone by, shallow burial sites gave rise to stories of ghosts wafting through cemeteries due to the release of the bioluminescent gas, phosphine (PH3). As a result, we learnt to bury our dead deeper.

Visual signs of these VOC, include shallow roots, which shear off abruptly along a horizontal line. These roots cannot live and breathe in these fermented layers. These areas will have lower quality growth, increased stress and reduced resilience during dry and hot conditions.

If thatch and undecomposed layers are over an inch deep, problems start to arise, as air flow is compromised. As a result, the conditions for disease set in, with insect pests, water repellency and nutrient breakdown. This creates a vicious downward cycle that can be hard to interrupt. With seven inches of thatch, the Montanan fields were in a world of hurt! This thatch has similar dynamics to The Bronx at the Cottonwood Ranch. Bacteria on the lignified root and grass materials, form water resistant waxes, repelling the irrigation water. In compacted soils or those with deep thatch layers, this is the time a mechanical intervention can be incredibly beneficial. Aerate or rip one inch deeper than the thatch layer to kick-start the system, by introducing air. Down these rip lines, you can use the same process as the horse stud at Lindsay Farms by dripping humic acid and sugar/molasses. In horticulture, managing post-harvest digestion, is critical to ensure diseases do not breed in between the growing seasons. Applying soil and leaf drenches with calcium-based sprays provides a hygiene clean-up. There are many commercial digestion products, or you could also make your own using a lactobacillus serum.