How to improve your soil health

Deferred grazing with R2 dairy heifers on daily or twice-daily shifts trampling spring grass surplus, keeping the soil covered, ‘resetting’ seeded grass plants into a vegetative state and evenly distributing manure (Photo Sam Lang)

Soil health (structure, biology, and nutrients) can be quickly changed through the management practices and systems used by farmers.

The ‘basic needs’ of healthy soils are described below, along with relevant principles and ideas of farm management practices that can help meet those needs and support improvements in soil health.

Check out the Quorum Sense Case Studies, Webinars and Event Videos for more in depth farmer-to-farmer sharing of soil health building systems and practices.

---

Air and Water

View fullsize

A diverse cover crop of annual and perennial plants sown to help alleviate compaction and build soil structure (and other things) in a vineyard row

Poor soil structure severely limits the flow of air and water through soils, reducing productivity, health and resilience.

Thankfully, soil structure can be improved relatively quickly if the right tools are applied in the right context.

Relevant principles of regenerative agriculture

• Maximise photosynthesis
  Green growing plants pumping more root exudates to feed more soil microbes will drive the formation of soil aggregates, creating small and large pore spaces for air and water to move through.

• Harness diversity
  Using a diversity of annual and/or perennial plants with different root systems help feed more root exudates to soil microbes. Plants with aggressive root systems can help physically open up compacted soils.

• Manage livestock strategically/holistically
  Animal hoof action can break up soil crusts. Maintaining pasture residuals and/or litter can change the microclimate of the soil surface, encouraging water infiltration and reducing evaporation.

Relevant practices

• Diverse cover crops

• Diverse pastures

• Diverse forage crops

• Grazing management

View fullsize

Cattle grazing a diverse forage crop including oats and daikon radish that have aggressive root systems that help improve soil structure

Tim Rutherford (from ‘How the Rutherford's healthy soils are restoring the water cycle in Central Otago’ case study)

Other things to think about:

• Mechanical aeration can help by breaking up any surface crusting, pans and/or relieving the impacts of pugging

• Certain biostimulants can help break down ‘biological crusts’ on the soil surface that prevent air and water infiltration.

• Mechanical and chemical soil disturbance can negatively impact certain soil microbe groups - especially fungi - who are essential to maintaining and improving soil health.

↑ Back to top

---

Food

View fullsize

Illustration of how plants create sugars (energy) from sunlight and share those sugars with soil microbes (Image from Integrity Soils)

Root exudates are the primary food source for soil microbes, followed by decaying plant roots and litter. Maximising the flow of root exudates to soil microbes will feed and drive soil microbial processes including nutrient cycling and aggregation.

Relevant principles of regenerative agriculture

• Harness diversity
  Diverse plant populations can capture more sunlight and more diverse/balanced soil microbe communities support better soil function.

• Maximising photosynthesis
  Increasing the time that green growing plants are present in soils, and/or increasing the health and brix of plants, can increase photosynthesis and amount of root exudates.

• Manage livestock strategically/holistically
  Pastoral farmers can use grazing management to target full plant recovery and maximise vegetative pasture growth, which both drive root exudates. Excess pasture growth can be trampled to cover the soil and provide an additional microbe food source.

Relevant practices

• Diverse cover crops

• Diverse pastures

• Grazing management

• Bale Grazing

Other things to think about

• Biostimulants, foliar nutrition, microbial foods (fish, seaweed, molasses etc) and fertilisers are tools that can (when applied in the right context) help increase brix levels and the flow of root exudates to soil microbes.

What are root exudates?

Plant root exudates coming from a root tip shown under a microscope (Image form Integrity Soils)

• Root exudates are carbon-based compounds (metabolites, amino acids, secreted enzymes, mucilage, and cell lysates) that are produced by plants via photosynthesis and are ‘leaked’ out into the root zone (rhizosphere) to feed soil microbes. This is sometimes called the Liquid Carbon Pathway.

• Root exudates are often referred to as ‘sugars’ for simplicity and are responsible for driving carbon sequestration and nutrient cycling.

• Anywhere from <10 to 44% of the sugars produced by plants are ‘leaked’ to soil microbes (Bais et al. 2006).

• Plants ‘code’ the root exudates that they ‘trade’ to communicate what specific nutrients that they need at any given time.

↑ Back to top

---

Soil Cover

Planned crop residue keeping the soil covered after a diverse winter forage crop has been grazed (Photo Sam Lang)

Maintaining soil cover protects the soil surface from direct sunlight and insulates against temperature extremes, creating a better habitat for soil microbes and insects to thrive.

Relevant principles of regenerative agriculture

• Manage livestock strategically/holistically 
  Promoting sward density, maintaining pasture residuals and in some cases trampling pasture all help to maintain soil cover.

• Harness diversity
  Diverse forage crops can be designed to incorporate species that act as soil litter/armour after the crop has been grazed, while diverse cover crops keep something growing between cash crops and can be terminated and retained as soil cover.

• Minimise disturbance
  Retaining crop residues and direct drilling help ensure soil cover.

Relevant practices

• Diverse forage crops

• Diverse cover crops

• Diverse pastures

• Grazing management

Tim Rutherford (from ‘How the Rutherford's healthy soils are restoring the water cycle in Central Otago’ case study)

↑ Back to top

---

Nutrients/Minerals

View fullsize

Grazing fully recovered pasture promotes more root exudates to feed soil microbes while leaving decent residuals and brown litter keeps the soil covered (Photo Sam Lang)

In healthy soils, plants and microbes work together to unlock and cycle nutrients/minerals bound in the soil profile, reducing or eliminating reliance on fertiliser inputs to maintain/improve production.

However some nutrients/minerals may be inherently low in your soils and difficult for even healthy soil microbe populations to access. Identifying and remedying these deficiencies may generate high returns on investment where they are a significant limiting factor (e.g., low molybdenum levels preventing clovers from fixing free nitrogen from the atmosphere).

Relevant principles of regenerative agriculture

• Plan for what you want; start with what you have
  Nutrient/mineral inputs may generate decent returns on investment as your remedy genuine deficiencies and build soil health. On the other hand, some farmers have been successful going cold turkey in their specific contexts.

• Open and flexible toolbox
  Regenerative principles emphasise that any tool/practice can have a place in the right context, for the right reason, including different types of fertilisers (conventional, biological, biodynamic etc). All can generate positive outcomes in the right context.

View fullsize

A diverse forage crop of kale, vetch and clover with ryegrass that provides soil cover post-grazing and rapidly recovers, ‘catching’ excess nitrogen and feeding soil microbes (Photo Sam Lang)

From ‘Learning off each other with Peter Legg - Quorum Sense Podcast #29)

Other things to think about

• Fertiliser inputs are often a significant expense. Consider using safe-to-fail trials to test the effectiveness of new or existing inputs.

• Do you have a nutrient/mineral issue, or a management issue (i.e. compaction)? Answering this question can save and/or generate large profitability gains.

• Different types of fertilisers are more ‘microbe friendly’ than others.

• The efficiency of fertiliser inputs can be enhanced through foliar application (i.e. Tow and Fert) and biological chelators (e.g. fulvic acid, fish hydrolysate)

• Soil nutrient relationships are complex - an excess can sometimes be more limiting than a deficiency.

↑ Back to top

---

In this article