Identifying your limiting factors

Identifying limiting factors is a process to see (in the words of Nicole Masters) “what is putting a drag on your system?“.

Another way to look at it is ‘a process to identify your low hanging fruit and prioritise your interventions and management changes’.

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Uncovering limiting factors

Jules Matthews from Mangaroa Farms sharing their journey of developing an intensive market garden and team (Photo Sam Lang)

While limiting factors are most often applied to soils and plants, it is also a useful way to think about mindset, people, money and infrastructure.

We have designed a simple Limiting Factors Work Sheet below to help you identify where and how to assess your limiting factors, record the results of your assessment and identify actions to take.

Download the Work Sheet and use the prompts, information and links in each section below to help you complete it.

Download the QS Limiting Factors Worksheet

• Limiting Factors Worksheet spreadsheet (Excel)

• Limiting Factors Worksheet (pdf)

• Limiting Factors Worksheet (docx)

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Image of Limiting Factors Work Sheet page 1 of 2 (click to enlarge)

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Limiting factors - Above the ground

Mindset

Our mindset can be the biggest barrier or enabler to developing regenerative farm systems. Essentially, it is our current ‘programming’ that guides our beliefs and decisions.

In regenerative agriculture, farmers often describe how they:

• see ‘failure’ as a learning opportunity

• start questioning past beliefs

• become more creative and innovative

• observe their soil/plants/animals in different ways

• look to natural/biological solutions before relying on chemistry and heavy metal

• become less stressed and more inspired

Do you have beliefs, attitudes and/or concerns that might be holding you back?

“…I don't think there's anything [that didn’t work] because if it didn't work, you at least learn something out of it. You don't get to know what you know, without knowing what you don't know… it's all a learning experience” - Dean Martin, Hawke’s Bay

Allan Richardon from Avalon Farm in Otago inspecting diverse winter crop residue and soil health (Photo Sam Lang)

Field day at Clyde McIntosh’s Canterbury dairy farm discussing pasture diversity (Photo Sam Lang)

People

Farm owner Greg Hart meeting volunteers at a tree planting day at Mangarara Farm, Hawke’s Bay (Photo Sam Lang)

We (farmers) are the biggest drivers of change or inertia.

Consider whether there is untapped potential for how you and/or your team operate and how that could impact the performance of your farm?

Things to consider could include; time, creativity, planning, fulfillment, responsibility etc.

Money and infrastructure

Money, infrastructure and other resource concerns or limitations can control or limit our options on farm.

Identify areas where this is the case as a starting point to exploring how you could adapt to or change that situation.

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Limiting factors - In and on the ground

Sunlight

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The process of photosynthesis (image from For The Love of Soil)

Sunlight provides the energy for almost ALL soil and plant processes, helping plants grow and also feeding soil microbes via root exudates. Farmers have little influence over sunshine BUT can influence how efficiently that sunlight is harvested via photosynthesis, and for what period of time. Some key principles include:

• Maximise (duration of) photosynthesis - maintain healthy green growing plants year-round

• Harness diversity - diverse plant populations can capture more sunlight

• Manage livestock strategically/holistically - grazing management has a huge role in maintaining dense swards of green growing plants

Nutrition also plays an important role in how efficiently sunlight is converted by plants into energy.

You can investigate whether sunlight capture is a limiting factor by:

• Looking at whether you have significant bare ground that is not capturing sunlight?

• Looking at your plant species diversity - do they collectively maintain a green and growing cover year round?

• Considering whether you are overgrazing and limiting plant growth?

• Measuring plant brix with a refractometer (see this Integrity Soils blog post).

Record what you discover and the actions you could take.

Air

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X-ray view of two neighboring orchard soils; the soil on the left has poor structure and restricted air/water flow (shown in grey), the soil of the right has been managed biologically and has developed good structure for easy air/water flow (Image from Integrity Soils)

Like people, soils need to breathe! They need good structure and aggregation to create pore spaces for air and water to move through. Well aerated soils enhance microbe activity, nitrogen fixation, drought and flood resilience, nutrient cycling and plant growth while reducing nitrous oxide emissions.

Soils with poor structure may struggle to perform even if soil nutrients are all optimum, but thankfully soil structure can be built (relatively) quickly.

See Toolbox pages Assessing Soil Health and Improving Soil Health for ideas and tools for diagnosing and improving soil aeration.

Record how you will find out, what you discover and the actions you could take.

Also check out:

• Soil Air - Breathing in and breathing out - Manaaki Whenua Landcare Research

Water

Water infiltration rates can be the difference between drought or a normal summer! This photo shows two Central Otago soils 20m apart on a boundary fence after recent rain. The soil on the left is managed biologically. The soil on the right is repelling water (Photo Sam Lang)

While we have limited control over how much rainfall we receive, we can influence how effective that rainfall is (the % that infiltrates into our soils) and how much we store in our soils (known as water holding capacity). Rainfall may be lost to runoff if soils are bare, compacted, capped, or hydrophobic (or if the rain is too heavy or soils already full!).

Is water the most important ‘nutrient’ on your farm? Are you making the most of what falls from the sky?

See Toolbox pages Assessing Soil Health and Improving Soil Health for ideas on diagnosing and improving soil water infiltration and water holding capacity.

Record how you will find out, what you discover and the actions you could take.

Diversity

Natural ecosystems are incredibly diverse and this diversity drives their productivity, health and resilience. Increasing plant, soil, insect and animal diversity on farm is key to enhancing natural processes like nutrient cycling, pest and disease resistance, soil aggregation etc.

Diversity help reduce reliance on high energy/cost inputs such as cultivation, agri-chemicals, and fertilisers (which often reduce diversity and therefore maintain our reliance on them!).

The Toolbox page Assessing Soil Health includes methods such as the VSA which also observe plant and insect diversity.

Record what you discover and the actions you could take.

Also check out:

• Toolbox pages Diverse Pastures, Diverse Cover Crops and Diverse Forage Crops for ideas of practices to increase plant diversity

• Lange et al. (2015) - Plant diversity increases soil microbial activity and soil carbon storage.

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Diverse winter forage crop with faba beans, vetch and sunflowers helping fix nitrogen and attract beneficial insects to support the kale and turnips, without needing nitrogen or chemical inputs. By winter this looks like a mostly kale crop (Image Sam Lang)

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Illustration of the Soil Food Web: all types of organisms are essential to support the natural soil function (source Manaaki Whenua Landcare Research)

Nutrient Cycling

In healthy soils, soil microbes digest, decompose, and cycle dung, urine, plant residues, organic matter and so much more. They also help unlock bound nutrients in the soil and make them available to plants.

Unhealthy soils with poor nutrient cycling will remain dependent on inputs to maintain plant productivity and and animal health.

You can investigate this limiting factor by:

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Rapid manure breakdown in early summer at Dean Martin’s farm in Hawke’s Bay

• Looking at whether your animal dung, plant litter or crop stubble breaks down quickly or slowly?

• Looking at your soils so see if they are thatchy?

• Seeing many earthworms per spade you have?

• And/or using other methods described in Assessing Soil Health.

Record how you will find out, what you discover and the actions you could take.

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Highly visible urine patches and old manure indicating poor nutrient cycling. A VSA of this pasture also reveals an evident thatch (Photo Sam Lang)

Farmers inspecting soil at a workshop - smelling soil can help identify whether soils are aerobic (forest floor smell) or anerobic (ammonia smell)

Nutrients

Soil nutrients are an important limiting factor to check. They are last in our list because a) it’s where farmers have typically been trained to look first, and b) it can be the most expensive intervention if other limiting factors are not addressed.

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Pink or red nodules on legumes indicate active nitrogen fixation by rhizobia. Trace elements including molybdenum and cobalt are essential for enabling this ‘free nitrogen capture’ process and can be easily identified and amended (Image Integrity Soils

Soil nutrient relationships are complex, as shown in the image of Mulders Chart, which is solely chemical relationships and does show the relationships between nutrients/minerals and soil structure or biology.

Many farmers have observed (some) soil tested nutrient levels increase after improving plant diversity and/or soil health, without actually adding any nutrients! This is soil biology doing the work. Similarly large return on investments can be generated where critical macro or trace element deficiencies are identified and amended.

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Consider whether it’s worth:

• Testing your soil for macro or micro nutrient deficiencies or excesses (which can be antagonistic i.e. aluminium)

• Testing your plants to see if soil nutrient deficiencies or antagonisms are showing up in your plants (or not)

• Testing both soil and plants at the same time to compare them.

• Looking for visual signs of nutrient deficiencies in your plant leaves, clover nodules and/or livestock.

Record how you will find out, what you discover and the actions you could take.

Nicole Masters and Graeme Sait discussion soil and plant health assessments at a workshop (Photo Sam Lang)

Farmer inspecting soils looking at roots, thatch and insects

Other things to think about

What other things could be limiting factors for your farm and/or business?

• Shade & shelter?

• Infrastructure?

• Nutrient transfer by livestock?

• Genetics?

• Planning & Management?

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In this article

Webinar co-hosts Sam Lang (Quorum Sense, Foothills Farming) and Jules Matthews (CREATE coach, Mangaroa Farms) present the limiting factors process, and Quintin Hazlett from Hukarere Station joins to help show how the process works.

This webinar was funded by Beef + Lamb New Zealand as part of the ‘Catch the Rain’ project.