If you want your garden to perform at its best, the soil needs to be healthy and suited for whatever you are growing. So what is healthy soil? To properly answer this we first need to know what makes up a healthy soil. The following are what I consider the important building blocks of a healthy soil.
- Inorganic matter - a main ingredient in most garden soils consisting of small rocks, sand, and clay.
- Organic material - an important ingredient in soil structure consisting of plant and animal residues that have not been broken down sufficiently to be available to plants.
- Organic matter - organic material that has been broken down by microorganisms into humus. The process provides soil nutrients and improves soil structure promoting both good water retention and proper drainage. (note: this distinction between organic material and matter is my own terminology as I feel is important to emphasize the distinction between what is and is not yet available to the plants).
- Air and Water - air in the soil is an absolutely necessary and is as important as water.
- Minerals - minerals are typically included in the inorganic matter but different soil structures and compositions may be lacking in some necessary minerals.These building blocks are not the whole story however. There are a number of other components that we need to take our soil to the next level.
Now the healthy soil picture starts to come into better focus. Inorganic matter has organic material added which is broken down by worms, insects, bacteria, molds and fungi into organic matter making the nutrients available to the plants. This cycle is known as the Soil Food Web. Preserving this Soil Food Web is one of the primary objectives to maintaining good garden soil.
- Worms and insects - both worms and insects ingest, digest, and redistribute organic material in the soil. They are part of the process of changing organic material into organic matter. They also aerate the soil promoting air and water distribution.
- Bacteria - necessary for the breakdown of organic material into organic matter so the nutrients can be used by the plants. Some bacteria actually colonize the plant roots promoting nitrogen uptake.
- Molds and fungi - the main role of mold and fungi is to break down the hard plant materials making it available to bacteria.
- Mycorrhizae - this is a special fungus that forms a close symbiotic relationship with plant roots. This fungus-plant alliance stimulates plant growth, accelerates root development, improves nutrient uptake, and increases drought tolerance.
- Nematodes and Protozoa - they eat soil bacteria and excrete the plant nutrients back into the soil making the nutrients available to the plants.
Unfortunately, just the act of gardening can disrupt the soil food web. We are regularly digging, dividing, and planting as well as tilling our soil to add organic matter. The unintentional result is that we physically disrupt the soil which disrupts the food web. So what's a daylily gardener to do?
I find that the first thing we can do is to be aware of what our actions can do to the soil food web. Dig only when we have to and use that opportunity to amend the soil at the same time. Otherwise, add organic matter or compost via top dressing and let the natural processes break it down and the worms will distribute it into the soil. We can also use a variety of materials that promote the organisms that make up the living part of the soil food web. These will be discussed later in this article.
We now have a vision of where we want to be with our garden soil. It's time to find out where our soil is currently. The recommended way to do this is to have a soil analysis done. There are vaious companies that provide soil analysis services. State or county extension services are a good place to start but there are also commercial services available. Here in Texas the Texas A&M Extension Service has a good program which provides a range of different tests. The routine analysis + micronutrients costs only $27 per sample (at this writing) and tests the following:
The soil analysis report usually includes suggested corrective measures for anything it finds that needs adjusting. There are also various organic soil amendments that can be used that will supply specific macronutrients and micronutrients. These will be discussed later in this article.
- Soil pH
- nitrogen (N)
- phosphorous (P)
- potassium (K)
- calcium (Ca)
- magnesium (Mg)
- sulfur (S)
- iron (Fe)
- manganese (Mn)
- copper (Cu)
- zinc (Zn)
The importance of proper soil pH - Soil pH is a measure of a soil's acidity or alkalinity.
Daylilies do best with a pH between 6.5 and 7 (neutral to slightly acid). In most cases, increasing the organic matter in your soil will go a long way toward bringing your soil's pH into the proper range. However, if your soil is too acid, it can be brought back to a favorable pH by applying agricultural (ground) limestone. Dolomitic limestone is preferred over calcitic limestone because it contains magnesium in addition to calcium. If your soil is too alkaline, Sulphur can be used to reduce the pH fairly quickly. You can also incorporate naturally acid organic materials such as oak leaves, oak sawdust, ground up oak bark, cottonseed meal, or acid peat moss but it will be slower acting. The best way to maintain the proper soil pH is to use plenty of organic matter in your garden.
Identifying and resolving poor soil structure
Soil can be classified into one of four major textural classes:
You can do your own test to determine your soil structure using a clear glass jar with a lid like a mason jar. Fill the jar half full with garden soil, add a teaspoon of dish detergent and then fill almost to the top with water. Tighten the lid and shake for several minutes so that the soil is in suspension before letting the jar set so the contents will settle. The sand will settle to the bottom fairly quickly. After 2 minutes mark the sand level on the outside of the jar. The silt will take longer to settle. After a couple of hours mark the silt level on the jar. The clay may take quite a while to settle so let it set for a couple of days before marking the clay level on the jar. The best garden loam will be about 40% sand, 40% silt, and 20% clay.
- Sand - relatively large particle size. Not good at retaining moisture or nutrients. Incorporating abundant organic material helps offset the moisture issues but organic material alone may not supply all the needed nutrients.
- Clay - very small particle size. It’s dense when wet and slow to absorb water when dry. Because it packs so tightly, plants have a difficult time growing in clay even though it can be rich in nutrients. Sand and lots of organic material can be added to clay to improve its structure. Avoid using ‘bank sand’ because it can include weed seeds or chemical residues from the river. Adding expanded shale will also help improve clay soil. Because clay retains so much water it can be beneficial to build raised beds when you have clay soil.
- Silt - particles are smaller than sand but larger than clay. It can be fertile but if the particles are too small it can suffer from some of the same issues as clay. Incorporating both sand and organic material is a good start toward making this a productive soil. Again, avoid using ‘bank sand’.
- Loam - This is a combination of sand, silt, and clay and is considered the best structure for gardens.
Beneficial soil additives.
There are numerous soil additives that are beneficial to your soil. The key to selecting the right additives is to consider how it will affect your soil food web. The following are some of my favorites.
Compost - Compost is the primary amendment for most gardens and is the foundation for a good soil food web. Compost is organic material that has been either partially or completely decomposed into organic matter by microbial action. You can make your own compost or it can be purchased but be aware that bagged compost may have been sterilized which kills off the beneficial organisms. Check the bag for the word 'sterilized'. Bulk compost, usually sold by the yard, is typically not sterilized.
In my opinion, unless already digging the soil the best way to use compost is as a top dressing. The nutrients will leach down into the soil as the plants receive water. Also, earthworms will eat some of the compost taking it down into the soil where the plants can access it. The reason I like this method best is because it does not physically disturb the soil or the existing soil food web. The down side of this method is that the soil builds from the top down and it can result in soil rising too high on plants like daylilies. This means the daylilies will periodically have to be dug to reset them at the proper growing depth. Here are some of the more common types of compost:
- Manure compost - This is made from various non-meat eating animals. Horse and cow manures are probably the most common. Chicken manure also makes good compost. Rabbit manure is considered one of the best manures, especially if the rabbits were fed alfalfa. Note: rabbit manure is one of the few types of manure that can be used directly in your garden without composting as it isn’t ‘hot’ and will not burn your plants. Whenever possible, obtain manure compost or manure for your own composting in bulk directly from a good source. Inexpensive commercial bagged manure composts contain relatively low amounts of manure and usually have been sterilized killing off the beneficial microbes.
- Leaf Mold compost - typically made from recycled leaves with manure added. The composting process is slow with the result being high in humus. While this compost can be found in 40 lb. bags it is much more economical to buy in bulk by the yard if you can find it.
- Vermicompost - also known as worm castings, is essentially worm manure. This can be purchased or you can make your own. Material used for vermicomposting is vegetable and food wastes such as fruits, cereals, grains such as corn meal, tea bags, coffee grounds, crushed eggshells, and other non-fatty kitchen scraps. The worms eat this material and excrete the work castings. Look on-line for further information on home vermicomposting.
- Mushroom compost – this is the medium used for growing mushrooms after the mushrooms have been harvested. It is relative high in nutritional value but has few microorganisms due to it being sterilized prior to use. It should be used in moderation because it can sometimes be high in soluble salts. If bought in bulk it can be left outside uncovered so some of the salts can leach out before applying it to the garden.
- Make your own compost using your own kitchen and yard wastes - There are lots of online articles on home composting.
Uncomposted organic material - Various organic material can be used as a mulch or top dressing. As the mulch breaks down it should be replenished periodically by adding additional organic material. The preferred materials are those that don't take a long time to break down. The idea is to have a constant cycle of organic material breaking down feeding the soil similar to the processes that go on naturally in our woodlands and forests. The downside to this is the same as for top dressing with compost. Daylilies will eventually have to be dug to reset them at the proper growing depth.
Alfalfa Pellets - The addition of alfalfa pellets to the soil stimulates vigorous growth. This is primarily from the nitrogen made available as the alfalfa breaks down but there are also growth hormones and important trace elements present in the alfalfa. The most obvious result is larger, more vigorous plants and the daylily foliage is a darker green than the foliage of untreated daylilies.
Care should be used when incorporating alfalfa pellets in the soil around the plants roots. During decomposition alfalfa pellets can give off heat and can result in the soil getting quite warm if too many are used. The best time for soil application is in the fall after the soil has become cooler and can dissipate the heat. Alternately, the pellets can be applied to the soil surface prior to mulching. Alfalfa is also a good additive when making a compost tea. Note that some alfalfa pellets have salt added. Avoid using these in the garden.
Humates - Sometimes called 'liquid compost', humates have been recognized as the single most productive input in sustainable agriculture. Humates consist of organic acids including humic and fulvic acid along with the raw humates (prehistoric plant matter) from which these powerful natural acids are derived. They can be purchased at specialty nurseries and online. Here are some of the benefits of adding humates to your garden as found in multiple places on the internet:
- adds humus to your soil
- the most concentrated organic matter available
- increases the efficiency of fertilizers
- increases nutrient uptake
- transforms insoluble nutrients into useable ones (especially iron)
- retards pathogenic fungi build-up while promoting beneficial fungi
- stimulates microbial activity
- increases drought tolerance
- improves seed germination
- it's an excellent root stimulator
- pH-buffering capacity
- flushes high levels of salts out of the root zone
- helps keep fertilizer from leaching through the soil
- promotes good soil structure
- Increases root growth
- capacity to detoxify chemical residues and heavy metals
- contains a growth stimulant capable of enhancing cell division and cell elongation
- A powerful, natural chelating agent
Beneficial Microrganisms - Microorganisms are already present in your soil but you can purchase products that contain microorganisms to give your soil a jump start. These products typically contain only the beneficial microorganisms and having a high population of the ‘good guys’ helps keep the unfavorable ones in check.
Digging and tilling the soil are a major disruption to the microorganisms in the soil food web. Of course digging is part of gardening as daylilies need to be periodically divided and we all like adding new cultivars. Adding beneficial organisms either right before or after digging can ensure that you have an abundance ready to quickly reestablish themselves as the soil settles.
Check with your local specialty nursery or look online. Examples of products:
- Many MicroLife brand products contain beneficial microrganisms
- EM-1® Microbial Inoculant
- SCD Probiotics Soil Enrichment
- BioOrganics MycoMinerals Ultimate Organic Soil Amendment
Agricultural Molasses - Agricultural molasses or blackstrap molasses is the byproduct of cane sugar processing. After the crystalized sugars have been removed, the remainder is the blackstrap molasses which is high in Sulphur and micronutrients. This makes it an ideal additive to your garden soil. An additional benefit to using molasses is that because it is high in sugars, it feeds the soil microorganisms thus increasing their population. That in turn is beneficial to the plants.
Epsom Salts - Epsom salt is not actually a salt but a naturally occuring mineral compound of magnesium sulfate. It has a neutral pH and breaks down into magnesium and Sulphur, both of which are important plant nutrients. Epsom salt does not build up in the soil over time, which makes it a safe soil additive. Both magnesium and Sulphur assist in the production of chlorophyll which results in greener foliage and improved blooming.
Coffee Grounds - Coffee grounds are an excellent addition to your compost pile but there are other uses that can benefit your garden. They can be worked in the soil where they will act as any other organic material improving drainage, water retention, and soil aeration. They also help beneficial microorganisms thrive. As they decompose they will become organic matter in the soil. Coffee grounds can also be spread on the soil surface as mulch. The grounds attract earthworms which like to feed on the grounds. The earthworms in turn will carry the grounds in their digestive tracts down into the soil where the digested matter will be available to the plants.
Some people are concerned that coffee grounds lower the pH (or make the soil more acidic). This is true for unused coffee grounds but once washed by the brewing process their pH becomes almost neutral.
Starbucks started the Grounds for Your Garden program back in 1995. They offer free 5 lb. bags of used grounds on a first-come, first-served basis where local codes permit. Not all Starbucks may participate so check before going to ask for grounds.
Organic sources of macronutrients and micronutrients - Should you find that your garden soil is deficient in one or more nutrients, the following organic sources can be used to add that nutrient back into the soil. Note that some of these are relatively slow acting and may not provide immediate results. If you need something fast acting, more information about each product can be found online.
- Composted manure from grass feeding animals
- Poultry manure
- Bat guano
- Fish emulsion
- Blood meal
- Feather meal
- Alfalfa pellets
- Cottonseed meal
- Chicken manure
- Rock phosphate
- Steamed bone meal (from cattle)
- Fish bone meal
- Bat guano (from fruit eating bats)
- Rock dust (crushed granite)
- Compost (especially if high in fruit & vegetable waste especially banana peels)
- Wood ashes (caution: can raise soil pH so check pH regularly)
- Kelp meal
- Granite dust
- Calcite (calcitic limestone) (caution: can raise soil pH so check pH regularly)
- Dolomite lime (caution: can raise soil pH so check pH regularly)
- Ground oyster shell
- Dried crushed egg shells
- Dolomitic limestone (caution: can raise soil pH so check pH regularly)
- Epsom salt
- Agricultural Molasses
- Epsom salt
- Usually there is plenty of iron in most soils but it is primarily in the form of insoluble rocks and minerals and therefore unavailable to plants. Adding humus (or humic acid) is the best way to make iron available to the plants.
- Blackstrap molasses
- Chelated iron can also be added if your soil is truly deficient in iron.
- Leaf mold compost
- Alfalfa pellets
- Blackstrap molasses
- Wood shavings
- Blackstrap molasses
- Grass clippings
- Alfalfa pellets
- Rock phosphate
- Granite Dust
- Rock dust
Lastly, you probably noticed that the emphasis on this information has been the 'organic' approach. There's no doubt that organic gardening produces great results but there are issues with a 100% organic approach. The main issue is that the organic approach is more labor intensive than the typical chemical fertilizers and sprays. Non-organic methods are quick fixes but don't produce the kind of results that can be obtained from a good organic approach because the soil food web is constantly in stress.
So what's the answer for those of us who don't have a lot of time and don't want to spend all our spare time working the garden instead of enjoying it? My suggestion is to try and follow the organic approach whenever possible and only revert to non-organic methods when you have to. Then be aware of what damage you might be doing to the soil food web with chemicals and try your best to mitigate any damage with a little extra dose of 'organic care' when time permits.