Walk between the rows of our coffee trees here in Holualoa and you will notice something most visitors overlook entirely. Their eyes go up, toward the dark green canopy of coffee leaves, toward the clusters of red and yellow cherries catching the afternoon light, toward the volcanic ridgeline and the ocean glimmering far below. Almost nobody looks down. But if you do, you will see it: a low, lush carpet of green growing between every row, plants that nobody harvested, plants that do not end up in a bag or a box, plants that most people would never think to ask about.
Those plants are some of the most important things we grow on this farm.
They are called cover crops, and they are the quiet workers of a healthy coffee operation. They do not produce a bean or a cherry. They do not go through our wet mill or our roaster. They do not appear on any label. And yet without them, the soil beneath our coffee trees would be a different place entirely, poorer in nutrients, more vulnerable to rain, less alive in every biological sense of the word.
Most farm conversations start with the coffee. We love those conversations too, and we have them every day on our tours here in Holualoa. But we want to give cover crops their moment, because they deserve it. If you have ever wondered how a farm maintains productive, healthy soil year after year on a steep volcanic slope in the tropics, cover crops are a big part of the answer.
In this article, we are going to explain exactly what cover crops are, what they actually do in a coffee growing system, why farms like ours depend on them, and how the broader farming world is catching up to what experienced growers have known for generations. We will also put this in the context of Kona's remarkable geography, because what makes Kona's growing conditions so distinctive shapes every decision we make about how we manage the land between our trees.
Let's start at the beginning, with a clear definition and an honest answer to why any of this matters.
What Are Cover Crops, and Why Do Coffee Farms Use Them?
The term "cover crop" gets used in a lot of agricultural conversations, but it does not always get explained well. For people who grew up around farming, the concept is second nature. For everyone else, including most of our visitors, it can sound a little abstract. So we want to build a solid foundation here before we get into specifics about what cover crops do and how we use them at Buddha's Cup.
The Basic Definition: Plants That Serve the Soil
A cover crop is any plant grown primarily to benefit the soil and surrounding ecosystem rather than to be directly harvested for sale or consumption. That distinction matters. When we plant Kona coffee trees, we are planting for a harvest. When we plant cover crops between those trees, we are planting for the soil itself, and by extension, for the long-term health of everything that grows in it.
Researchers and agronomists in Brazil have started calling cover crops "service plants," which is a useful phrase. These are plants that perform services for the farm: holding soil in place, feeding soil biology, managing moisture, suppressing competing weeds, and contributing organic matter when they decompose. They are not passengers. They are workers.
The idea of keeping "living roots and protective residue in fields" is central to the soil health movement that has gained enormous momentum over the past decade. Living roots do things that bare soil cannot. They exude compounds that feed soil microbes. They create pathways for water and air to move through the soil profile. They hold soil particles together against the force of heavy rain. And when the plant dies or is cut back, its biomass becomes food for the next generation of soil life. The cycle is elegant and self-reinforcing once it gets going.
Cover crops tend to come from a few main plant families, each with different strengths. Legumes, like clover, cowpeas, and various beans, are prized for their ability to fix atmospheric nitrogen. Grasses, like sorghum, millet, and rye, produce large amounts of biomass and have dense root systems that excel at erosion control. Brassicas, like radishes and turnips, are sometimes used to break up compacted soil with their taproot structure. In tropical and subtropical coffee systems, legumes tend to be the most common choice because nitrogen fixation provides such a direct benefit to coffee plants, which are heavy nitrogen feeders. But many farms use mixtures of species to capture multiple benefits at once.
One more clarification worth making: in coffee farming, cover crops are typically intercropped, meaning they grow between the coffee rows, not instead of them. The coffee trees stay in place. The cover crops fill the spaces between, working the soil and protecting the surface while the permanent crop continues to grow above them.
Coffee Farms Are Not Like Corn Fields: Why Coffee Needs Ground-Level Protection
If you have ever seen a conventional grain farm, you know what bare soil between rows looks like. It is common and, in many contexts, manageable because those crops are replanted each season and the land is relatively flat. Coffee is different in almost every way that matters for soil health.
Coffee is a perennial crop. The same trees stay in the ground for decades, sometimes longer. That means the soil beneath them does not get turned over and refreshed with tillage the way annual crop soil does. Whatever happens to that soil over time, good or bad, compounds. Good practices build on themselves. Poor practices also build on themselves, and the damage accumulates silently until it becomes visible in the trees themselves.
Coffee is also grown on sloped terrain, often at significant elevation. Here in Holualoa, we are farming on the slopes of Hualalai volcano, at an elevation that puts us squarely in the cloud zone that makes this area so famous for its afternoon rains. Those rains are part of what makes this region so productive. They are also, on bare soil, a significant erosive force. When heavy tropical rain hits exposed soil on a slope, it does not just get the soil wet. The impact of individual raindrops physically dislodges soil particles from the surface. Water then moves downhill, carrying those particles with it. Over seasons and years, this process can move enormous amounts of topsoil from where it needs to be, in the root zone, to somewhere it cannot help anyone.
The afternoon rains that make Kona's belt so productive are, in other words, the same force that makes soil protection so essential. This is not a contradiction. It is just the reality of farming in a genuinely productive climate: more water means more growth, but it also means more runoff risk on unprotected soil.
Ground cover changes this equation dramatically. When living plants cover the soil surface, raindrops hit leaves and stems before they hit the ground. Their impact is absorbed and dissipated. The roots hold the soil particles in place. Water infiltrates rather than running off. The difference in erosion rates between covered and bare soil on a slope can be dramatic, sometimes an order of magnitude different depending on rainfall intensity and slope angle.
Cover Crops vs. Shade Trees: Different Tools, Shared Goals
People who know a little about sustainable coffee farming sometimes ask whether shade trees serve the same purpose as cover crops. The honest answer is that they serve overlapping but distinct purposes, and the best farms use both.
Shade trees operate at the canopy level, above the coffee trees. They moderate temperature, reduce water stress, provide habitat for birds and beneficial insects, and contribute leaf litter that becomes mulch on the soil surface. Research has increasingly shown that shade trees function as a vital climate buffer for coffee plants, moderating the kind of heat stress that is becoming more common as climate patterns shift. For farms at lower elevations or in drier regions, shade trees can be the difference between viable and non-viable coffee production under changing conditions.
Cover crops operate at ground level, below the coffee canopy. They work the soil directly, in the zone where coffee roots live and where water and nutrients either stay or leave. Their contributions are different from shade trees: physical erosion control, biological nitrogen fixation, soil organic matter building, and direct weed suppression in the inter-row space.
Think of them as two layers of a system. Canopy above, ground cover below, with the coffee trees in the middle benefiting from both. This layered approach is consistent with what we practice here on our farm, and it reflects the full-circle approach to how we manage our land, treating the farm as an integrated ecosystem rather than a collection of isolated inputs and outputs.
Now that we have a clear picture of what cover crops are and where they fit in a coffee farming system, we can go deeper into what they actually do, function by function.
The Core Functions of Cover Crops on a Coffee Farm
Cover crops do not do just one thing. That is part of what makes them such a valuable tool in a farm system. Each species and each management approach contributes in slightly different ways, but across the board, cover crops deliver a cluster of related benefits that reinforce each other over time. Here we will walk through the primary functions one by one, with enough detail to make each one meaningful rather than just a bullet point.
Erosion Control: Keeping Volcanic Soil Where It Belongs
We mentioned erosion in the previous section, but it deserves its own deeper treatment because it is arguably the most urgent reason to maintain ground cover on a sloped tropical coffee farm. Erosion is not an abstract threat. It is a slow, ongoing process that can quietly degrade a farm's productive capacity over decades, often without obvious visible signs until the damage is significant.
The physics of erosion on sloped coffee land work like this. When a raindrop hits bare soil, it creates what soil scientists call "splash erosion." The impact detaches soil particles from the surface aggregate and propels them outward. On a slope, gravity then takes over. Those detached particles, along with any organic matter or nutrients attached to them, move downhill with surface water flow. Over time, this removes the finest, most biologically active layer of soil from the surface, the layer that took the longest to form and that contributes the most to plant nutrition.
Cover crop root systems physically bind soil particles together. The roots themselves thread through the soil, connecting particles to each other and anchoring them against the force of water moving over the surface. Above ground, the plant canopy, even a low one, intercepts rainfall before it hits the soil directly. By the time water reaches the soil surface, its energy has been absorbed by stems and leaves. Splash erosion is dramatically reduced. Surface runoff is slower and carries far less sediment.
In Kona's context, this matters enormously. The volcanic loam soils on the slopes above Holualoa are genuinely irreplaceable on any human timescale. They formed over thousands of years as volcanic rock weathered and biological activity built organic matter into the mineral substrate. That process cannot be hurried. Once that topsoil leaves the field, it is gone for practical purposes. No amount of fertilizer inputs can replicate what took millennia to accumulate. Protecting it with ground cover is not just an environmental preference. It is an economic necessity for any farm that intends to be productive for future generations.
The economic dimension of this cannot be overstated. Lost topsoil means declining productivity, which means either investing in more and more synthetic inputs to compensate or accepting lower yields. Neither outcome is sustainable. Ground cover that prevents erosion is preventing a cost that would otherwise compound indefinitely into the future.
Nitrogen Fixation and Nutrient Cycling: Free Fertility From the Air
Nitrogen is the nutrient that coffee plants need in the largest quantity. It drives leaf and stem growth, supports the metabolic processes that produce chlorophyll, and is a key component of the proteins and enzymes that keep the plant functioning. Conventional farming addresses nitrogen demand by applying synthetic nitrogen fertilizers, typically derived from fossil fuels through the energy-intensive Haber-Bosch process. This is expensive, it has significant environmental costs, and it does nothing to build the soil biology that makes natural nutrient cycling possible.
Leguminous cover crops offer a fundamentally different pathway. Legumes form symbiotic relationships with rhizobia bacteria that live in nodules on their roots. These bacteria take nitrogen gas from the atmosphere, which is about 78 percent nitrogen by volume but completely unavailable to plants in its gaseous form, and convert it into ammonia and then into forms that plants can actually absorb and use. This process is called biological nitrogen fixation, and it is one of the most remarkable and agriculturally important biological phenomena on earth.
When a leguminous cover crop is mowed or incorporated into the soil, all that fixed nitrogen becomes available to other plants, including the coffee trees growing nearby. It is, in a very real sense, fertilizer manufactured by living organisms using nothing but air, sunlight, and the carbon compounds the plant produces through photosynthesis. The input cost is essentially zero beyond the seed. The benefit can be substantial, reducing or eliminating the need for synthetic nitrogen applications in well-managed systems.
But the story does not stop at nitrogen. Cover crop roots also release a variety of organic compounds called exudates into the surrounding soil. These exudates feed an extraordinary diversity of soil microorganisms: bacteria, fungi, protozoa, nematodes, and many others that together form the soil food web. This microbial community performs functions that no synthetic fertilizer can replicate: cycling phosphorus into plant-available forms, releasing mineral nutrients from rock particles, suppressing soil-borne pathogens, and forming mycorrhizal associations that extend the effective reach of coffee roots far beyond what the roots themselves could access.
Recent research published in Frontiers in Agronomy suggests that "cover crop root exudates and earthworm burrows may have created localized hotspots of fertility" in the soil around coffee plants, concentrating biological activity and nutrient availability in ways that benefit the coffee root system directly. These hotspots are not visible from the surface. You cannot see them on a farm tour. But they represent real, tangible improvements in the conditions that determine how well a coffee tree grows and how resilient it is to stress.
The volcanic soils that give Kona coffee its mineral complexity are already rich in many trace elements by nature, a legacy of their geological origin. Cover crops help make those minerals accessible to plants by supporting the microbial activity that reveals them from their mineral matrix. It is a partnership between geology and biology that plays out slowly and continuously in the soil beneath our trees.
Weed Suppression, Water Retention, and Organic Matter Accumulation
These three functions are grouped together not because they are less important than erosion control or nitrogen fixation, but because they are deeply interconnected. Each one reinforces the others in ways that make the whole greater than the sum of its parts.
Weed suppression might seem like a secondary concern, but on a coffee farm, managing competing vegetation between rows is a significant labor cost. Conventional approaches typically involve either mechanical cultivation, which can damage surface roots, or herbicide applications, which raise their own concerns for soil biology and environmental quality. A well-established cover crop offers a third option: biological competition. When a cover crop densely covers the soil surface, it shades out the germinating seeds of weeds that would otherwise establish themselves in the inter-row space. Those weed seeds need light to germinate, and a thick cover crop canopy denies them that light. The result is natural, non-chemical weed management that reduces labor input and avoids the costs and risks associated with herbicide use.
Water retention is another compounding benefit. Dense cover crop root systems improve soil structure by creating networks of pores and channels through which water can move downward into the soil profile rather than running off the surface. This is called infiltration, and it is critically important in both wet and dry periods. During heavy rains, good infiltration means less runoff and less erosion. During dry spells, it means more water has been stored in the soil where coffee roots can access it. The same structural improvements that help in the rain help in the drought, which is a remarkable property for a simple management choice to deliver.
Organic matter accumulation is perhaps the slowest of these benefits to materialize, but it is also the most durable and far-reaching. Every time a cover crop is cut back or dies, its biomass breaks down. Soil microorganisms consume it, releasing some nutrients immediately and incorporating others into stable organic compounds that persist in the soil for years or decades. Over time, this process raises the organic matter content of the soil, which improves water holding capacity, feeds the soil food web, sequesters carbon, and creates the spongy, dark, biologically rich topsoil that every farmer recognizes as a sign of genuine soil health.
This is not a quick process. Building meaningful organic matter takes years of consistent management. But once it accumulates, it is self-reinforcing. More organic matter means more soil life, more soil life means better nutrient cycling, better nutrient cycling means healthier plants, healthier plants produce more biomass, and more biomass means more organic matter. Cover crops are one of the most reliable ways to initiate and sustain that positive cycle.
All of these functions, erosion control, nitrogen fixation, weed suppression, water retention, and organic matter accumulation, represent long-term investments that pay increasing returns over time. This is why cover crops are not a quick fix or a seasonal experiment. They are a commitment to building a farm system that gets better with every passing year.
Cover Crops and the Bigger Picture of Regenerative Coffee Farming
Cover crops do not exist in isolation on a well-managed farm. They are one component of a larger approach to farming that is increasingly described as regenerative agriculture. Understanding where cover crops fit in that broader philosophy helps explain why we care about them so deeply at Buddha's Cup, and why the conversation about soil health in coffee farming has expanded so much in recent years.
What Regenerative Farming Actually Means in a Coffee Context
The term "regenerative agriculture" has become more common in recent years, and like many popular terms, it carries the risk of being used so broadly that it loses its meaning. So let us be precise about what we mean when we use it in a coffee farming context.
Regenerative agriculture refers to farming practices that actively rebuild soil health, biodiversity, and ecosystem function over time. The key word is "rebuild." This is not simply about sustaining what is already there, which would be a maintenance goal. And it is emphatically not about the extraction model of conventional agriculture, which treats soil as an input medium that can be substituted with enough synthetic fertilizer. Regenerative farming treats soil as a living system that can be degraded or improved by human choices, and it deliberately chooses the practices that improve it.
In coffee farming, regenerative practices typically include shade trees above the canopy, cover crops at the ground level, composting of organic waste including coffee pulp and husks, reduced or eliminated tillage to protect soil structure, and the development of biodiversity corridors and habitat features that support birds, pollinators, and other beneficial organisms. No single practice is sufficient on its own. The power of a regenerative system comes from how these practices work together, each reinforcing the others and contributing to a whole that is greater than any individual component.
It is worth noting that regenerative coffee farming is not a single certification or a standard that you either meet or fail to meet. It is better understood as a direction of travel. Farms can be more or less regenerative depending on how many of these practices they have adopted, how consistently they apply them, and how long they have been building in that direction. The goal is continuous improvement of the farm ecosystem over time.
The global reach of this movement is growing fast. In Minas Gerais, Brazil's largest coffee-producing state, state-level programs have been expanded specifically to promote cover crops in coffee fields, recognizing that soil health management is essential to the long-term viability of coffee production in that region. This is not a fringe idea practiced by a handful of idealistic small farms. It is a direction that major coffee-producing regions are formalizing into agricultural policy. The recognition at that scale reflects decades of on-the-ground evidence from farmers who saw what cover crops and regenerative practices did for their land and stuck with them.
Biodiversity Above and Below: How Cover Crops Support a Living Farm Ecosystem
When most people think about biodiversity on a farm, they think about the visible stuff: birds in the trees, bees visiting flowers, butterflies moving between plants. And cover crops do support that visible biodiversity. Flowering cover crops attract and feed pollinators. Ground-level cover provides habitat for ground-nesting birds and beneficial predatory insects that help control pest populations. A farm with diverse ground cover looks and sounds different from a farm with bare soil between its rows, and those differences reflect genuine ecological richness.
But the biodiversity story that is most important for soil health plays out underground, where it is invisible to casual observation. Diverse plant species at the ground level mean diverse root systems, diverse root exudates, and diverse food sources for the soil biological community. Different plant families support different species of bacteria and fungi. Different root architectures create different soil structures. The result of diverse cover cropping is a more diverse soil ecosystem, one with more functional redundancy, meaning that if one type of organism is stressed or reduced, others can fill its role and maintain the overall function of the system.
This microbial and fungal diversity below ground has practical consequences for coffee tree health. Diverse microbial communities are better at suppressing soil-borne pathogens than simpler communities. Mycorrhizal fungi, which form symbiotic associations with plant roots, are more abundant and more diverse in soils with varied ground cover and reduced tillage. These fungi can extend a coffee tree's effective root system many times over, accessing water and nutrients that the roots themselves could never reach. A coffee tree with a healthy mycorrhizal network is more resilient to drought, more efficient in its use of soil nutrients, and less dependent on external inputs to maintain productivity.
Recent research on integrated management approaches in coffee systems demonstrates that combining multiple agroecological practices, including cover crops, shade trees, reduced inputs, and biological diversity, produces results that are greater than what any single practice achieves alone. Recovery of degraded coffee systems is faster when these practices are implemented together rather than in isolation. The whole really is greater than the sum of its parts, and cover crops are an essential piece of that whole.
Does Soil Health Affect Cup Quality? What Farmers Believe and What Research Suggests
This is the question that connects everything we have been discussing to what most people actually care most about: the coffee in their cup. And it is worth answering honestly, because the science here is genuinely complex.
The direct causal chain from soil health to cup quality is difficult to isolate in controlled research. So many variables affect flavor, from variety and rootstock to altitude, microclimate, harvest timing, fermentation practices, and roasting, that attributing specific flavor characteristics to soil management practices requires careful experimental design that is not always practical on working farms. We want to be honest about that complexity rather than overstating what has been definitively proven.
What we can say with confidence is this: healthy soil produces healthier plants, and healthier plants produce better quality fruit. That connection is well established. Coffee trees growing in biologically active, nutrient-balanced soil with good water retention tend to show more consistent cherry maturation, stronger resistance to pest and disease pressure, and greater resilience during the environmental stresses, dry spells, temperature variations, that inevitably affect production in any given year. More consistent cherry quality going into harvest means more consistent potential for quality in the cup.
The emerging research on localized fertility hotspots created by cover crop root activity and soil biology suggests that the soil around healthy, biologically active root zones genuinely is a richer environment for plant growth. Plants growing in that environment have access to more nutrients, more water, and more biological support than plants in depleted soil. It is reasonable to think that this advantage expresses itself in fruit quality, even if the precise mechanisms are still being studied.
At Buddha's Cup, we believe that how we treat the soil shows up in the cup. That belief is informed by what we observe on our own farm over years of practice, by the experiences of other farmers who have adopted similar approaches, and by the direction that research is pointing even where it has not yet produced definitive conclusions. The foundation we build in the soil is the foundation for everything that follows, including where coffee cherries are fermented on-site after harvest and through every step of processing that transforms a healthy cherry into a remarkable cup.
This soil-first philosophy is inseparable from our full-circle farming approach, which treats every part of the farm system as connected to every other part, from the cover crops between the rows to the coffee in your morning cup.
Cover Crop Use Is Growing: What the 2026 Data Shows
It is one thing to describe the benefits of cover crops from our perspective as a small Hawaiian coffee farm. It is another to place those benefits in the context of what is happening in agriculture more broadly. The data from 2026 makes clear that cover crop adoption is not a niche practice or a romantic notion. It is a mainstream, expanding agricultural strategy supported by farmer experience and economic evidence alike.
The 2026 National Cover Crop Survey: Key Findings
Every year since 2013, the Sustainable Agriculture Research and Education program, the Conservation Technology Information Center, and the American Seed Trade Association have collaborated on a national survey of cover crop use in the United States. The 2026 edition is the ninth in that series, and its findings reflect a continued, sustained expansion of cover crop adoption across American agriculture.
This year's survey gathered responses from 657 farmers across 46 U.S. states. The average cover crop acreage among respondents reached 397.9 acres per farm, and projections suggest that this figure will cross 400 acres per farm by next year. That is a significant scale of adoption, and it represents real commitments of land, seed investment, and management attention by thousands of farmers across a wide range of crop types and geographies.
Perhaps the most telling finding from the survey is this: nearly half of all respondents had ten or more years of experience with cover crops. This is not a population of curious experimenters trying something new. These are experienced, committed farmers who adopted cover crops, saw real results, and kept doing it year after year. That persistence is the most powerful endorsement any agricultural practice can receive. Farmers do not spend money on something that does not work, especially not for a decade.
The survey also documented expanding uses for cover crops beyond traditional soil health applications, including cover crop grazing, the use of drones for precision planting and management, and diversified planting patterns that mix multiple species to capture a wider range of benefits simultaneously. This kind of innovation within cover crop practice reflects a maturing field, one where early adopters have done the foundational work and the mainstream is now refining and improving on those foundations.
It is important to note that this survey covers broad U.S. agriculture, not specifically coffee farming. Coffee is grown in a relatively small geographic area of the United States, primarily in Hawaii and a few other locations, and it represents a tiny fraction of total U.S. agricultural acreage. But the cultural shift in how farmers across the country are thinking about soil management is mirrored in coffee-growing regions globally. The same logic that is driving corn and soybean farmers in the Midwest toward cover crops is driving coffee farmers in Brazil, Colombia, and Hawaii toward the same practices. The specifics vary by crop and climate, but the underlying soil science is universal.
Long-Term Adoption: What the Economic Data Tells Us
Survey data on adoption rates is useful, but the economic data may be even more persuasive for farmers evaluating whether cover crops make sense for their operation. The USDA Economic Research Service published a comprehensive analysis of the persistence of cover crop use in U.S. crop production from 2012 through 2022. That decade-long dataset reveals something important: farmers who start using cover crops tend to keep using them.
Persistence over time is a meaningful signal. If cover crops were simply a trend, or if they failed to deliver real results, farmers would try them once and move on. The fact that the data shows sustained, long-term adoption across a diverse range of farm types and regions suggests that farmers are observing genuine, tangible benefits that justify the ongoing investment.
What does that investment look like? Cover crops do have upfront costs. Seed purchase, establishment (whether by planting, drilling, or aerial application), and management during the growing season all require time and money. For small and mid-size farms, these costs are real and need to be weighed carefully. The economic case for cover crops is not that they are free. It is that they pay back their upfront investment through reduced costs in other areas over time.
Farmers who have used cover crops for multiple years consistently report reductions in fertilizer spending, particularly nitrogen fertilizer, as biological fixation and nutrient cycling take over some of the work that purchased inputs previously did. Many also report reductions in herbicide spending as cover-driven weed suppression reduces the need for chemical weed control. And over longer timeframes, the improvements in soil structure and water holding capacity can contribute to more stable yields during weather stress events, which represents a kind of economic resilience that is difficult to put a precise dollar figure on but is very real in its effects.
For a farm like ours in Holualoa, where we are working with volcanic soil that took geological time to form and that cannot be replaced if it erodes away, the economic logic of soil protection is especially clear. Every year that our cover crops hold the soil in place is a year that our most valuable long-term asset, the soil itself, retains its productive capacity. That is not an abstract environmental benefit. That is the economic foundation of our farm's future.
What We Plant at Buddha's Cup and How We Manage It
We have covered a lot of general information about cover crops in coffee farming, and we want to bring it home to what we actually do here on our farm in Holualoa. Because the specifics of how you manage cover crops matter as much as the decision to use them in the first place. Cover crops managed poorly can create problems. Cover crops managed thoughtfully become one of the most reliable tools in a farmer's kit.
Species Selection for Kona's Conditions
Choosing the right cover crop species for a specific location requires understanding that location's climate, soil type, and the specific challenges you are trying to address. In Kona, we are working with a tropical climate that has distinct wet and dry seasons, though the afternoon cloud patterns in Holualoa mean we receive reasonably consistent moisture even during drier periods. Our soils are volcanic in origin, well-draining by nature, and relatively young in geological terms, meaning they benefit significantly from the organic matter and biological activity that cover crops contribute.
Leguminous species are our primary focus because nitrogen fixation addresses what volcanic soils most commonly need supplementation with. Varieties like sunn hemp, cowpeas, and various clovers are well-suited to tropical conditions and can establish quickly, providing ground cover and biological activity within weeks of planting. Sunn hemp in particular is well-suited to warm, humid environments, grows rapidly enough to outcompete most weeds during its establishment phase, and fixes substantial quantities of nitrogen when incorporated into the soil.
We also incorporate grass species in some areas, particularly where erosion risk is highest and we want maximum root mass for soil stabilization. Grasses do not fix nitrogen, but their extensive, fibrous root systems are unsurpassed for binding soil particles and building the kind of soil structure that improves water infiltration. Used alongside legumes in a mixed cover crop planting, they complement the nitrogen-fixing benefits of the legumes with structural benefits that legumes alone cannot provide as effectively.
In some areas of the farm where mamaki grows naturally or where we have encouraged its establishment, we see natural ground cover working in concert with our managed cover crop plantings. Mamaki, the native Hawaiian nettle, is not planted as a cover crop in the traditional sense, but its presence between our rows contributes to the overall biological diversity and ground-level protection that we are trying to achieve. It also, of course, provides us with the leaves we use for our mamaki tea, a naturally caffeine-free herbal tea with a long history in Hawaiian wellness traditions. Having it grow naturally on the farm is one of those genuine gifts that a biodiverse farming approach can produce.
Mowing, Timing, and Integration With Coffee Management
Managing cover crops on a coffee farm requires coordination with the coffee growing cycle. During the peak growing and fruiting season, we want cover crops that are actively growing and providing their full range of soil services. During harvest, we need access between rows for picking, so cover crop height needs to be managed accordingly. And at certain points in the cycle, cutting back or incorporating cover crops allows their accumulated biomass and fixed nitrogen to