The Seven Tenets of Sustainable Gardening Draft
Back when I was running TomatoCulture Farm, we followed “The Seven Tenets of Sustainable Production” to produce top quality heirloom tomatoes. I apply the same tenets in the home garden and reap higher yields, better flavors and fewer problems. In a nutshell, this means I try to work with nature, rather than against it. As you develop an understanding of natural systems and learn how to make them work for you, it minimizes labor and cost while at the same time conserves valuable natural resources such as soil and water.
My gardening practices include the use of cover crops and “green manures” to build soil structure and fertility; inter-planting and species diversity; integrated pest management, water efficiency, mulching, and minimal tilling. The goal is to get as close as possible to a self-sustaining ecosystem that takes advantage of nature’s principles to achieve long-term stability and productivity. This approach fosters metabolizing systems that together generate more value than the sum of their many biochemical parts.
In a metaphysical sense, natural systems, perfected over billions of years, function outside of our own objective human experiences. In the theoretical place called nature, no one is there adding fertilizers; no one is weeding or watering; nobody is adding compost or applying pesticides. These things all sort of happen on their own. They are components of ancient, closed loop ecosystems that take care of themselves without us; but we cannot live without them. They provide what are referred to as “ecosystem services” – the transformative and life sustaining benefits from nature on which we humans rely for survival. These services include things like clean air and water, topsoil, pollination, food, climate regulation, waste cycling, biodiversity, etc.
In 1994, a group of esteemed Pew scientists and economists got together to discuss the implications of declining ecosystems in traditional economic terms. Their mission was to try to apply economic principals – normally associated with human production of goods and services – to nature’s ecosystem services. From these discussions came an important paper called “The Value of the World’s Ecosystem Services and Natural Capital” (Robert Costanza et al, 1997 British Journal of Nature) that estimated the global value of ecosystem services at an average of $33 trillion per year (since then revised upwards significantly). These services are so fundamental to human life that they are easily taken for granted, and until this paper was published, there were no attempts to measure their economic value. In a simple illustration, it’s easy to grasp the monetary insurance value of a coastal community of hotels and condos destroyed by hurricane flooding after ecosystem services (i.e., cypress swamps, mangroves, sand dunes, etc.) were removed without any thought to their value.
When associated with ecosystem services, the term sustainability takes on a much broader meaning. For our little part, it means following the seven tenets of sustainable gardening:
Obey Your Sense of Place
I am glad I waited to take the Master Gardener course until I arrived in New Mexico 12 years ago. Had I trained back in Pennsylvania, a lot of that knowledge would not be relevant to my current situation. It’s always funny to me when people move to the Southwest from East of the Mississippi and go for the familiar Kentucky bluegrass sod, Japanese maples, dogwoods, azaleas, and blueberry bushes that the nurseries are peddling. The fact is our soils are vastly different from the soils back East. Those acid and moisture loving plants struggle in our dry, limey, alkaline soils. Kentucky bluegrass needs 40 inches of rain a year to stay green, we get nine inches in a good year. Here in New Mexico, our soils tend to have very low organic matter (usually around 1%), limited moisture, and an alkaline pH of 8 or higher. All these factors impact the carbon cycle and nutrient uptake, which are critical to a productive growing system.
The soil example above perfectly illustrates the importance of place when planning a garden or a farm. However, attention to your sense of place pertains not only to soil, but also climate, materials, water, plants and culture. For example, the New Mexico sunshine is so intense that even sun loving plants like the tomato appreciate – and rely on - partial shade, which I provide for my plants. Here are just a few strategies to help you obey your sense of place:
Pay attention to your growing zone, daylight hours and frost dates to better understand the length of your growing season. The strength of your light will increase until the summer solstice and then begin to decrease until the first day of winter. Find out the latitude for your area and use this handy Daylight Explorer to know your light patters throughout the season. Contact your county Cooperative Extension office for your growing zone and first and last frost dates.
Conduct a soil test. A soil test is one of the best things you can do to practice sustainable growing. A good soil testing lab will give you valuable knowledge of your soil’s primary and secondary nutrient content, pH level, salinity, and percentage of organic matter – all the critical components that influence soil health. A good soil test may be available for as low as $25 through your state’s Cooperative Extension. If not, check neighboring states or any number of private labs. I have used Colorado State University’s soil testing lab. More recently, I have used ServiTech Labs in Texas. They offer a range of professional testing services with great turnaround times and reasonable prices.
Look for plant species and varieties that are adapted to your local climate. Here in New Mexico, we have desert conditions, so drought tolerant plants are essential, as well as plants that are tolerant of higher pH levels. I have also been able to find lists of vegetable varieties that do particularly well in our areas. These are varieties that have been grown extensively and successfully by others in our state. Your state’s land grant university will likely have free research-based publications available online that focus on your local region, like this example of shade trees that do well in New Mexico.
Use materials that are abundant in your area. For example, fall leaves are a fantastic source of organic matter and nutrients that can be saved, shredded, composted and applied to your soil. In my area I have a lot of ponderosa pines and their fallen needles make an excellent mulch. If you have a lush green lawn that you mow periodically, use the grass clippings as organic mulch. Spread them thinly at first so they dry out some; then you can layer them over time to make an excellent soil cover that helps regulate soil temperature, retain moisture and add organic matter. Don’t use grass clippings if you have recently applied an herbicide. If you need stone for landscaping, it is cheaper if it is sourced locally, and it will also add to the authenticity of your landscape.
If you obey your sense of place, taking advantage of what nature serves up, you will work less, save money, and you will be more sustainable
Nourish the Soil
The soil itself is a natural system and it is deeply tied to “place”. It is the foundation of life that makes everything else work. Our soils support a mostly invisible and highly complex ecosystem made up of bacteria, fungi, amoebae, mites, worms and beetles. Working in concert, these organisms create humus, which supports plant life by assisting with the transfer of water and nutrients to the plants’ roots. Plants in turn provide nectar and cover for insects, and together they support the vertebrate food chain.
Scientists know, although still cannot fully explain, that soil organisms help protect plants from disease and transfer certain essential nutrients. We know that a humus molecule is made up of negatively charged oxygen ions and these attract and hold positively charged micronutrients (cations) such as Copper, Potassium, Ammonium (N), Magnesium, Zinc, Manganese and Calcium. In this excellent article on “How Humic Substances Benefit Soil and Landscapes” Michael Martin Meléndrez discusses the science of humus and how it can transform depleted soil, even in harsh physical environments, into healthy, productive soil.
The best way to build humus? Add organic matter. Here in New Mexico, where our terrain is dry, alkaline, and low in organic matter, the task of nourishing the soil is critically important if you want to grow food. The best strategy is to add organic matter and encourage root zone activity with cover cropping. The root zone is where the circus of micro-organisms starts working on new organic matter, breaking it down into successively smaller and smaller particles. The last particles left are humus. For happy plants, humus is your best friend. Here are some great ways to add organic matter to your soil:
Start a compost pile. Here in the desert, composting can be challenging, but it is possible if you put a source of water on your pile and cover it with a plastic sheet. Back east, composting happens much more naturally and easily because there is so much moisture and in turn high nitrogen or “green” organic matter. Due to the arid climate where I live, we are abundant in carbon or “brown” materials and lacking in green materials. Good sources of nitrogen include coffee grounds (huge quantities free from coffee shops like Starbucks); all plant-based kitchen scraps minus any fats; poultry manure; fresh grass clippings without herbicides; all your yard waste, clippings, trimmings, weeds that have not gone to seed, etc. One of the best investments you can make is purchasing a chipper-shredder. Shredded materials compost much faster. Another way to shred your materials is to run them over with a lawnmower.
Keep all your organic matter on site. Up in the Albuquerque foothills where I live, I laugh every time I see people paying landscapers to rake and leaf-blow every scrap of organic debris and haul it away. I prefer to keep as much organic “waste” on site as possible, especially the pine needles that accumulate on the ground from our ponderosa pine trees. I shred everything up and use it as mulch around my garden where I want it. If you prefer to have a clean yard, try asking your service provider to shred everything and apply the waste material as mulch where it’s needed.
Cover your soil. This strategy is critically important in the arid West, but it is a smart approach no matter where you are. A thick layer of mulch creates a micro-environment on the soil surface, regulating moisture and temperature and encouraging microbial activity that extends down to the root zone. Your soil and your plants will be much healthier with even moisture and temperature levels. Additionally, mulch prevents erosion from high winds, which we get frequently in the spring.
Use cover crops. Cover crops are of increasing interest in sustainable farming and the research coming back from the field regarding their use has been overwhelmingly positive. American farmers everywhere are discovering the favorable cost/benefit tradeoff of planting cover crops; in fact, on U.S. cropland, the use of cover crops increased by nearly 50 percent between 2012 and 2020. This guide from SARE.org runs through all the major benefits of cover cropping, which are used to restore soil quality and fertility, manage erosion, retain moisture, reduce weed pressure, control pests, shelter wild life and foster biodiversity. On the farm and in my home garden, I use nitrogen fixing cover crops like hairy vetch, peas and clover, as well as other beneficial plants such as buckwheat and rye grass.
Strike A Balance
Natural systems are all about balance. When equilibrium is lost, the whole system can begin to collapse, such as when we clear-cut trees from the side of a mountain or remove large predators from the food chain. In the garden, balance comes in the form of many little parts that make up the whole. Good examples are rain runoff to rain harvesting, good bugs eating bad bugs, ground cover and mulch stopping erosion, and the Carbon-Nitrogen cycle.
The Carbon-Nitrogen cycle provides a great lesson in balance. These two elements need to be in balance for the soil’s biology activity to flourish and provide nutrients for your plants. The ideal ratio is 20-25 parts Carbon to one-part Nitrogen. If this ratio is out of balance, the soil activity starts to die. For example, when we add a high NPK (Nitrogen, Phosphorous, Potassium) fertilizer to the garden, soil organisms respond by aggressively consuming the nutrients and multiplying rapidly. They consume available carbon in the process. If there is not enough Carbon (i.e., organic matter) available, the microbial activity dies out over time, leaving the soil inert and lifeless. Toby Hemenway, in his permaculture book, Gaia’s Garden, describes this process as being “analogous to a whopping metabolic rush that a big dose of sugar can give you: a great short-term blast, but one that depletes other nutrients and leaves you drained.” To make matters worse, many pest organisms have adapted to survive in these depleted conditions and seek out your plants as the sole source of carbon.
You can strike a balance in the garden or on the farm with the following tactics:
Add organic matter: Add plenty of organic matter to your soil to aid in the carbon/nitrogen balance. Compost is the single best source of organic matter. Manures are fine, too, but they are best if composted or allowed to “mellow” for a few months before adding. Covering the soil with organic-based mulches is another way to foster biological activity at the soil surface and build up the percentage of organic matter.
Don’t rely on high number fertilizers: I use higher number fertilizers sparingly as a soil building ingredient. For example, a high nitrogen fertilizer is useful to help kick-start the decomposition of organic matter that has been added to my soil, such as a winter killed cover crop. It is also important to choose fertilizers that contain trace minerals and humic substances such as humic acid, which are critical to carbon cycling and plant nutrition.
Minimize soil disruption. Limit tilling to facilitate planting, and bed formation, but keep as much of the root zone intact as possible to allow the soil ecosystem to develop. Deep and frequent tilling disrupts the biological cycles that help convert organic matter to plant food. I use a broad fork, which is an indispensable garden tool to help you lift and aerate the soil without disrupting the distinct layers. A good quality broad fork isn’t cheap, but it is a very good investment.
Interplant with flowering species. Any farm or garden landscape should include flowering plants, including herbs, flowers, shrubs and trees. The umbelliferous flowers are a great option to attract beneficial insects – not just bees and other pollinators, but also predatory insects that can keep pests in check. These plants are from the Apiaceae family (commonly known as the carrot, dill or parsley family) and have umbels, or clusters of tiny flowers small enough for predatory insects such as parasitic wasps to insert their mouth parts to gather nectar. Other flowers in this family include cilantro, baby’s breath, caraway, fennel and celery.
Create habitat for vertebrate predators: Attract snakes, toads and other garden predators to your plot. You can accomplish this with a water source, shelter such as a wood pile or other cover and a little patience.
Manage Water Wisely
In the Desert Southwest, wise water management is a given, but it is also important in places where there is, or has always been, abundant water. A year of drought in these places can be devastating because people are generally unprepared. So, it is best to be ready when a crisis strikes and manage this precious resource. Wise water management does require some pre-planning and creative design work to create infrastructure that puts the water where it can be useful instead of just running off to the street, or watershed, eroding the land and picking up pollution as it moves downward.
For an outstanding resource on Water management, check out the Brad Lancaster’s web page and award-winning book series “Rainwater Harvesting for Drylands and Beyond.” In his lectures, Brad tells us that, in Tucson, AZ where he lives, more rainwater falls in one year on the surface area of the city than the entire city consumes from the municipal water supply. The problem is that in most urban environments, the strategy for managing water is to move it quickly out of the landscape and into storm drains and culverts. Over time, the landscape begins to suffer from this loss of water, creating a progressive decline in soil health, which in turn reduces the landscape’s ability to absorb water. As this happens, the speed and violence with which runoff accumulates and surges away from the landscape increases, creating an ever more challenging and expensive water management situation. As Brad likes to say, “our drainage infrastructure gets rid of our free water.”
The critical components of wise water management include contouring the landscape to take advantage of the movement of water based on slope and directing it to plants and trees. Here are some great strategies that we use on the farm and that you can use to improve your gardens and landscapes:
Mulching is an essential way to prevent evaporation and water loss between rain events, especially here in the desert. As a bonus, mulch encourages biological activity in the soil and moderates soil temperature, which is important for healthy plants. On the farm, we used drip irrigation on our raised tomato beds and mulched with plastic to hold in the moisture. Tomatoes require even moisture and mulching is the single best way to achieve this balance. If you obey your sense of place and look for mulching materials that are available to you, it will require a lot less effort and money. At home, I try to use what is plentiful, including fallen leaves and pine needles. I grow cover crops to create extra plant material that I can mow and use for mulch.
Obey micro-climates, which are created by various structures in the landscape. Shade, fences, walls, trees, and sheltered courtyards are good examples. If you live in a wet climate and have a plant that does not tolerate soggy soil, pick a south facing location on a slight slope to ensure the soil drains and dries more quickly. Here in the Desert Southwest, I use partial shading over my tomato plants, which creates a cooler microclimate around the plants on the hottest days, sometimes as much as 10 degrees cooler. In turn, there is less evapotranspiration from the plants leaves and the surrounding soil, reducing our water use. The plants pollinate and set fruit better under the shade cloth when the ambient temps are inhospitable.
Use native and water wise plants Looking back at Sense of Place, using native and water wise plants is another great way to manage water. These plants require a lot less effort and cost a lot less over the long term in terms of water. They are easier to establish and perform much better over the long term with less input and labor.
Create humus! Good soil tilth will give your soil moisture holding capacity. We build our soils with cover crops and manures, which add organic matter to the soil and in turn humus. Add as much compost as possible to your soil in the spring and fall. Over time you will begin to see earth worms and the soil will take on a light crumbly texture with plenty of moisture holding capacity.
Contouring is a design concept aimed at capturing and storing rainwater rather than let it run off your property. It takes advantage of the land’s natural undulations and slopes and directs water where you want it. Good examples include creating a crescent shaped basin on the downhill side of a tree, or more simply capturing excess water from your roof using rain barrels and underground tanks and cisterns. Some communities are starting to allow “curb cuts” which directs some street run-off onto your property. For more information on contouring, check out Brad Lancaster’s book, referenced above.
Encourage Diversity
My herb garden, which encompasses about 150 square feet, has 24 different species of plants, most of which have small flowers that attract pollinators and predatory insects. This garden sits adjacent my raised beds where I grow my vegetables. I have other small beds of flowering plants around my property for the same purpose. After several seasons, I’ve noticed my aphid populations have declined dramatically. In fact, insect problems in general are minimal in my garden. I attribute this to a healthy ecosystem of beneficial bugs that keep the pest populations in check.
