Small Water Cycle

The Necessity of Water:

It is difficult to imagine a world without water. Nearly everything we do is reliant on water – from our own bodies and all the life around us to processing and production systems. As we work towards land stewardship and regenerative practices, we discover that we have a lot of work to do in restoring the water cycle. In this document, we will explore the more “localized” version of the water cycle known as the “small water cycle”.

The Small Water Cycle: 

The small water cycle is a feedback loop. Groundwater is absorbed by the roots of plants, trees and shrubs, transpired into the air and returned back to the land again in the form of rain. Water moves through plants via transpiration culminating in evaporation from aerial parts, such as leaves, stems and flowers. We will look at three areas that affect this process: the soil, the plants and the trees.

Soil and the Small Water Cycle: 

An important factor in the small water cycle is the soil’s ability to hold water. Good soil is like a sponge and is resistant to compaction (displaying a “chocolate cake-like” texture). Water infiltration is optimized and runoff is minimized. This also helps create healthy groundwater, which in turn improves plant health and the entire water cycle.

Plants and the Small Water Cycle: 

“An imbalance in plant nutrition creates a need for more water” – John Kempf
Healthy plants simply operate in a more efficient and resilient manner than unhealthy plants. This, in turn, both reduces the plants’ need for water and increases transpiration. Maximizing plant coverage through intercropping and poly-cropping will also enhance this process.

Trees and the Small Water Cycle: 

First Nations knowledge keepers have a saying: “The trees can call the rains to them”. Science has begun to catch up with this ancestral knowledge. We now know that trees, particularly multi story arrangements, slow down the air which gives water droplets a higher chance of forming.

To Conclude: 

As we integrate regenerative knowledge and practices into traditional farming, we begin to get a sense of the overlapping nature of the principles and processes. At the end of the day, this is the nature of holistic practice. 

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Transpiration is the process through which water moves from the soil, through a plant’s body and into the atmosphere. Learn more about this process and how it’s the foundation of the small water cycles.

All Living Things Need Water

The very first forms of life have been traced back to water. Without water, life as we know it would look entirely different or may not even exist. Modern day plants require water for many metabolic processes. From photosynthesis, to transpiration, to forming rigid cell structures, water is used constantly to provide nutrition, metabolites and structure to all parts of the plant. Here we will focus on the notable features in plants that move water around the entire plant body.

It All Starts At the Roots

Plant roots are composed of highly permeable cells that take up nutrients and water from the soil, and the vasculature in the roots shoots these metabolites up to the plant above ground. The vasculature is composed of xylem, which carries water and nutrients, and phloem, which brings water and sugars to all parts of the plant.

Moving Up the Stem

As the metabolites get pushed up the roots toward the top of the plant, they get transferred from the roots to the stem, the branches, the leaves, and finally out of the leaves in a process known as transpiration. Xylem brings nutrients and water upward, but not downward. Phloem brings sugars and water up and down the stem where they are used for cellular respiration and growth.

Entering the Leaf

Leaves are packed with organelles called chloroplasts which are the primary sites of photosynthesis, and they contain a pigment called chlorophyll that gives plants their green colour. Water is shipped to the chloroplast to be used for photosynthesis, along with metabolites such as carbon dioxide, nitrogen, etc. The greener the plant, the more photosynthesis is occurring, the more sugar is being produced, etc.

What’s the Stomata With That?

As water is produced via cellular respiration, plants finish transpiration by releasing water into the air through pores in the underside of leaves called stomata. The stomata open to exchange gases with the atmosphere, releasing water. They close when they need to reduce gas and water loss.

The Cycle Continues

The water cycle promotes the pathway that water takes within a plant, and in optimal conditions, is continuous. This natural progression of water through the plant’s vasculature is one of the many ways that plants have evolved to utilize water efficiently within their unique roots and shoots.

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Just like the nutrient cycle, the water cycle has no beginning nor end, and there is no starting or stopping point. The main objective for a farm is to capture as much water as possible and effectively utilise it to promote plant growth and soil health. So how does water cycle through the planet? Water cycles through evaporation, precipitation, infiltration, and transpiration, and these naturally occurring steps will be described in this document.

What Does a Non-Functioning Water Cycle Look Like?

Precipitation falls and meets scattered plants and exposed soil. If the precipitation cannot infiltrate the soil, it displaces it and leaves a trail of erosion, as well as pollutes downstream waterways. With less water able to soak into the soil, this makes the soil more susceptible to drought conditions. Compact soil also traps CO₂ and prevents oxygen uptake.

What Does a Functioning Water Cycle Look Like?

Solar energy is the main player in evaporation. Bodies of water like oceans, lakes and rivers are constantly exposed under the sun, and the solar heat turns these liquids into gases in the atmosphere. Soil also experiences evaporation when water escapes from pores in the ground. The moist air that is created through evaporation, plus water that travels through plants into the atmosphere (transpiration), rises to higher levels in the atmosphere. This air condenses in cooler temperatures, creating clouds that are saturated with water droplets. Once the cloud is sufficiently saturated and cooled, the clouds break and water droplets begin to fall in the form of precipitation. Snow and rain fall on the ground, and plants protect the soil by absorbing the impact of precipitation. Rain droplets gently seep into the ground. Any water that is not absorbed by the soil becomes surface runoff, which eventually leads to a freshwater body. Then, water in the soil feeds springs and creeks to keep water cycling through greater bodies. As the water enters the soil, it is consumed by plant roots and microbes for metabolism. The roots develop huge networks underground between fungi and their own root hairs to maximise surface area and optimise absorption.

When Plants Cover the Soil:

• Soil temperature decreases
• Evaporation reduces
• Soil gains greater resilience to drought
• Soil aggregates better to permit more gas exchange
• Microbe networks below ground are protected

Conclusion

In a functional water cycle, water transformation and utilisation is maximised in a continuous flow for all life on the planet. This ecological process is crucial for creating a regenerative organic farming system and for restoring soil health.

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The small water cycle, also known as the short/local water cycle, demonstrates how moisture  circulates locally across land. It begins with evapotranspiration (the combined process of  evaporation [water changing from liquid to vapor from soil and surfaces] and transpiration [water  vapor releasing from plant leaves]), where water evaporates from soil and plants, ascending into the  atmosphere as vapor. This vapor then condenses to form clouds, resulting in precipitation, such as  rain, which returns moisture to the land. This ongoing interplay of evapotranspiration and  precipitation facilitates a continuous exchange of water between the land and atmosphere, sustaining moisture levels within the region over time. 

The Importance of the Small Water Cycle  

The small water cycle, driven by the evapotranspiration process over land, is essential for local precipitation patterns and ecosystem stability. Human activities, like intensive agriculture, disrupt  this cycle, leading to reduced soil absorbency, increased temperatures, and irregular rainfall. When there is insufficient water in the soil, the sun’s energy, which would normally facilitate evapotranspiration, instead raises the temperature of the air and land, contributing to altered precipitation patterns. To address these challenges, initiatives closely tied to efforts to rebuild soil health and restore natural water management systems are essential. 

Rebuilding Soil Health to Restore Natural Water Management  

The small water cycle is disrupted due to degraded soil health, where rainfall evaporates into the atmosphere instead of infiltrating the compacted, carbon-deficient soil. Healthy soils are rich in  organic matter, have good structure, and are full of microbial life, allowing them to retain moisture  and support plant growth. For plants to grow and transpire water back into the atmosphere—where  it can fall again as local rain—soils must be healthy and carbon-rich. This improves water  infiltration, enhances the small water cycle, retains more water in cooler soil, generates greater  local rainfall, reduces fire intensity, and helps create essential cloud cover. Restoring degraded soil  will bring local temperature and rainfall benefits and positively impact the wider climate. By  redesigning cropping and grazing practices to repair small water cycles, both farmers and the  natural environment will benefit.  

Effective Precipitation > Rainfall Volume  

People often focus on rainfall volume, but the true concern is effective precipitation. Without  effective precipitation, rain struggles to nourish plants or replenish groundwater. Soil, like a sponge,  should absorb water, but if it’s as impenetrable as a brick wall (compacted), even heavy rainfall  won’t hydrate it. So, it’s not just about rain falling from the sky; it’s about the soil’s ability to embrace  and make the most of every drop. And that all ties back to the importance of maintaining healthy soils.

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If you’re wondering how the small water cycle is functioning in your area, a few quick observations after a rainfall will get you started. Ponding water and soil crusting/capping are both visual indicators of small water cycle dysfunction.

Soil Ponding
Ponding occurs when soil receives more water than it can absorb (infiltrate). This can happen during periods of heavy rainfall, causing water to collect on the surface instead of soaking in. Such pooling often occurs in low-lying areas, resulting in puddles – ‘ponds’.

Causes 

Soil type influences drainage and ponding. Finer-textured soils, like clay, tend to hold more water but drain slowly, leading to increased chances of ponding. Coarser, sandy soils tend to hold less water but drain quickly, reducing chances of ponding. However, in all soil types, increased amounts of organic matter allows for better infiltration (less ponding) while compaction increases ponding (less infiltration).

Terrain topography, particularly slope, also plays a crucial role in determining where water accumulates, especially in concave areas where runoff can gather. Additionally, microtopography, such as small bumps or depressions, influences the flow of water across the landscape. In low-lying areas, water can rapidly accumulate in the soil, causing the surface to become still or stagnant if not managed effectively. This stagnant water remains in place without flowing or draining away, leading to issues like ponding, where water collects in pools on the surface.

Land management practices, particularly concerning soil compaction, significantly influence the occurrence of ponding on agricultural fields. Compacted soils, which have less pore space for water to move through and drain slowly, are more susceptible to ponding and runoff. This risk is heightened by practices like heavy machinery usage, which can worsen soil compaction and diminish the soil’s ability to absorb and drain water efficiently. Alternatively, practices that increase soil organic matter, such as adding manure or incorporating crop residues, can improve soil structure, enhance pore space, and reduce the risks of ponding and runoff.

Consequences  

Ponding, where water stands on the soil surface for a prolonged amount of time can harm plants and soil health. It displaces air pockets in the soil, depleting oxygen in as little as two to four days, resulting in oxygen deprived, stressed plants. Stagnant water worsens oxygen loss and promotes soil pathogens, attacking seeds and seedlings, slowing growth, and increasing disease risk.

Mitigation and Prevention  

To prevent and mitigate ponding, it’s crucial to focus on improving soil structure to enhance water infiltration. This can be done by emphasizing practices that are aligned with the regenerative principles that prioritize minimal disturbance and soil armor. Healthy soils, nurtured through practices like conservation tillage, retain moisture longer. By minimizing soil disturbance, conservation tillage promotes soil aggregation, preserving soil structure and enhancing its ability to absorb water efficiently.

Incorporating cover crops like tillage radishes further promotes soil health by increasing organic matter and fostering beneficial microbial activity. Mulching or leaving crop residues in the field, another essential practice, acts as a protective layer, shielding the soil surface from erosive forces and reducing runoff.

When possible, planting flood-tolerant perennial species in areas that are prone to ponding is a great way to improve soil health and reduce the headaches of repeated crop failure/poor performance in these localized areas of the field. These integrated strategies work synergistically to enhance soil health, increase water holding capacity, and minimize the impacts of ponding and flooding on agricultural lands.

By adopting these regenerative practices, you can build soil resilience, reduce the need for external inputs, and cultivate sustainable farming systems that are better equipped to withstand extreme weather events and environmental challenges.

A quick observation to gauge soil health and water infiltration: Healthy soil should resemble  chocolate cake, not chocolate pudding. 

Soil Capping and Crusting

Soil capping or crusting refers to the creation of a sealed “cap” on the top layer of the soil. This often results from heavy rain pounding the soil – destroying its structure leading to a compaction of the soil surface. Once this cap develops on top of the soil, the soil surface becomes somewhat impenetrable to infiltration by water and air and makes passage by microbes difficult.

How Does Capping Occur? 

Capping can be seen in fields and other areas of bare land that display a cracked texture with an apparent “crust” on the surface. Capping/crusting can be the result of soil compaction due to extended periods of soil erosion caused by repeated plowing or tillage paired with the impact of rain. Overgrazing or bare ground exposure can also leave soils vulnerable to capping, however it is often more prevalent in high clay soils and high magnesium soils. These soils, sometimes known as “gumbo”, are particularly susceptible to crusting because soil particles in these areas are much smaller and more plate-like, making it easier for them to settle closely together, forming a tight cap over the soil. This can be seen when flood waters subside, leaving behind heavily crusted, often cracking soils.

How To Mitigate Soil Capping 

The good news is that in most cases, this capping and crusting can be mitigated through regenerative practices. The act of “armoring” the soil using plant cover and crop residues can help alleviate this issue by protecting soil surfaces and preventing the problem from getting worse. Incorporating cover crops, extending the growing season and increasing soil biology can provide a more long term solution; helping to break down existing crusts/caps and preventing their reoccurrence.

The Truth About Capping 

There can be a great deal of confusion regarding the term “capping”. Don’t get confused! An internet search will turn up a variety of unrelated topics including: capping as a process used in the remediation of old landfill sites to prevent the release of toxins capping of an abandoned well to seal out impurities from entering the aquifer capping as in setting an upper limit to the amount of nutrients allowable as inputs.

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