If you have been following my articles for a while you know that I often say “Don’t put chemical fertilizers on your plants!” But you’re probably asking, “Well, darn – then what fertilizers should I use Dom?” But before I answer that, let me talk a minute about why you should never use these chemicals on your plants or in your soil.
So, if you follow good organic practices, you know that the health of your soil is really, well… everything. Your soil must be uniformly moist and fertile, but much more important, it must be “alive!” You may not know that in a healthy garden, a plant’s roots are only responsible for 10% of the water and nutrient uptake of the plant. The other 90% is provided to the plant by the filaments of beneficial fungi that connect to, and deliver these nutrients to the plant’s roots. This network of filaments extends several feet in all directions. The main problem with high nitrogen synthetic fertilizers is that they kill off these fungi, leaving your poor plant to fend on its own (with 90% less food and water). It is easy to see why a plant living in a healthy soil can grow, thrive, cope with drought, and fight off bugs and disease so much better than one in a chemically saturated, depleted and dead soil. Another reason these chems hurt your soil is that they are, for the most part, salts (like sodium nitrate for example). They acidify your soil and leave salt residues behinds that build up, burn the plant’s roots, and eventually migrate up to the top layer of soil as it dries forming a crust. This crust can burn and kill off any fresh seedlings that try to push through and sprout. The salt build up also makes it harder for water to penetrate and reach the plant’s roots. Being water soluble, they also leech through the soil bed and go on to contaminate ground water. Like I said – BAD ;(
Thus, you should “Avoid like COVID” using any synthetic chemical fertilizers. These include chems like Ammonium Nitrate, Potassium Sulfate, Urea, Ammonium Phosphate, Super (or Triple) Phosphate, Ammonium Sulfate, Potassium Chloride, Calcium Nitrate, etc. While you might see a quick result from these chemicals, like a plant growth spurt, they are what I call a “Fix That Fails” – the long term effects are a decrease in yields, decline in plant health, increased susceptibility to diseases and insects, and permanent or long-term damage to the soil. There is no free lunch…
Of course you can foster healthy growth and vibrant health for your plants all while building soil vitality at the same time. Just follow along and you’ll find out how. There are four strategies to accomplish this, using: soil amendments, soil inoculants, organic fertilizers, and mineral fertilizers. Think of soil amendments like “pre-biotics.” I guess I’m always comparing your garden soil to your own gut – they are alike in so many ways. Anyhow – I digress … soil amendments, like compost, provide the raw material for soil health and also encourage the right kind of biotica to grow in your soil (sort of like dietary fiber). Soil inoculants contribute dormant beneficial microorganisms to the soil (like a good gut pro-biotic). Organic fertilizers, like Bone Meal, feed your plants as well as the soil microorganisms (like a healthful diet); and mineral fertilizers supplement the necessary minerals that might be in low supply or availability in your soil (like your daily vitamins). Let’s look at these categories one at a time. I will refer to the NPK of each, so as a quick refresher, the Nitrogen (N) in the fertilizer fosters quick green growth of leaves and strong chlorophyl production, the Phosphorous (P) builds stems and vigorous roots, and Potassium (K) is essential for fruit and seed production. Of course it is a little more complicated than this, but in a simple way, I like to think of Nitrogen = Leaves, Phosphate = Roots, and Potassium = Fruit. After a little thought, this should lead you to employ different amendments for different kinds of plants. Quick growing corn, for example, needs Nitrogen during its fast leaf-growth cycle, and then more Potassium as it develops the corn cob. Let’s look at some of the best organic soil amendments out there (the numbers indicate the NPK ratios of each):
SOIL AMENDMENTS (pre-biotic)
Compost or Compost Tea NPK 2-1.5-1.5 is teeming with all kinds of beneficial microorganisms that help convert soil nutrients into a form that can be readily absorbed by your plants (chelating). The microorganisms, enzymes, and natural antibiotics that are present in compost actually help prevent many diseases and make your plants resistant to insects. Earthworms, millipedes, and other macro-organisms are stimulated and encouraged by compost and tunnel through your soil, opening up passageways for air and water to reach your plants’ roots. Till liberally into soil and also use as a top dressing or mulch around your squash, tomatoes, eggplant, etc. Soaking some compost in a bucket full of water also makes a great liquid boost to pour around your plants – Its called Compost Tea.
Peat Moss NPK 1-.1-.1 is dead fibrous material that forms when mosses and other living material decompose in peat bogs. It can be purchased in bales (usually expensive) and is best worked well into the soil. The main benefits of peat is that it slightly lowers soil PH, which is usually good for Hawaiian soil, it holds onto moisture, and it lasts a lot longer in the soil than compost. Apply 3-4” of peat to your garden soil and till it in well. I use it extensively in my asparagus beds because a good asparagus bed can produce for 10 years, so you want the amendment to last.
Earthworm Castings NPK 2-1-1 are a superb but expensive soil amendment option (unless you make your own) that are rich in soil inoculants (desirable microorganisms) and humus, and provide essential plant nutrients, including iron, but they also work to improve the structure of soil. These promote plant health and resistance to insects like whiteflies in ways that are not yet understood. Use them if you can get them! They are often found mixed with compost – just make sure the compost is organic.
Organic Chicken Manure NPK 5-3-2 and chicken manure-based packaged blends like Perfect Blend provide fast nitrogen and trace elements. It is good for incorporating into your soil for most any crop and is also an inoculant for building a healthy soil biotica – but don’t over use it. It is also superb for spreading on your compost pile to boost nutrients and speed its decomposition.
Cow or Horse Manure NPK .5-.5-.5 performs similarly to chicken manure, however, you need a lot more of it, and it is most often NOT organic (meaning it may contain chemicals, antibiotics, and growth hormones) and is too high in salt. Still, if watered in well, it can be OK to use on trees. Don’t use “Milorganite,” however, which is processed human waste – hopefully I don’t need to say why….
“Green Manures” (NPK depends on the crop) are cover crops that are planted solely with the goal of improving the soil. These are planted thickly in your off season, usually left to mature, then tilled into the soil to decompose slowly and add their nutrients back into the soil. These include buckwheat, vetch, rye, and my favorite by far, alfalfa.
SOIL INOCULANTS (pro-biotic)
Mycorrhiza NPK 0-0-0 is not a fertilizer per se, rather it is a symbiotic microorganism that connects plants with colonies of beneficial bacteria and fungi throughout the soil. It vastly increases the availability of nutrients like phosphorus, calcium, sulfur, and all those elements necessary for plant growth and vitamin production in crops. A little goes a long way, so a light dusting of planting holes is all that is needed.
Legume Inoculant NPK 0-0-0 is a very special purpose bacteria that lives in the root nodules of legumes like beans and peas. With this bacteria, legumes are able to produce their own Nitrogen from the air. This inoculant is only used on legumes and is either rolled onto wet beans or peas before planting or sprinkled lightly in the planting trough. I always use these inoculants with my bean crops.
ORGANIC FERTILIZERS
Humate NPK 2-.5-.5 consists of humic and fulvic acid along with the raw humates (prehistoric plant matter) that strongly stimulates beneficial fungi, including mycorrhizal fungi. Think of it as compost that is hundreds or thousands of years old. Humates are the only known substance with the ability to hold onto every other nutrient in the soil, enabling heightened nutrient absorption.
Bone Meal NPK 4-20-0 is a great source of calcium and phosphorous. This makes one of the best amendments for root crops like beets and carrots. A handful in each hole when planting your tomato starts will ward off “Blossom End Rot,” that ugly black scab on the bottom of a tomato (it’s a calcium deficiency). Since regular Bone Meal may not be organic (because it comes from cow slaughter houses) it better to use Fish Bone Meal if you can find it – this is my most used fertilizer in my gardens.
Fish Meal NPK 4-12-0 Due to its high nitrogen levels, fish meal is a fairly fast-acting natural fertilizer. It also has good amounts of phosphorus and calcium. It is especially good for corn crops. It breaks down slowly and adds additional nutrients over time.
Kelp Meal NPK 1-.2-2 contains small amounts of the main three fertilizer components but it’s quite high in trace elements like Iodine (an essential element for Thyroid health). It is also a good source of growth hormones that can help plants reach their full potential by supporting root development. I add this to my gardens regularly.
Alfalfa Meal NPK 2-1-1 provides a nice balance of the major nutrients, namely nitrogen, phosphorus, and potassium, but also magnesium and sulfur. This balance makes it one of the safest fertilizers to use. Alfalfa also contains the growth hormone triacontanol, which can supercharge your garden. This is why Alfalfa Meal is one of my favorite fertilizers.
Crab Meal NPK 3-3-0 is made from crushed-up seafood byproducts that contain plenty of calcium and some phosphorous as well as a large quantity of trace minerals. This is especially good to work into your carrot and beet beds because the shell meal also contains an element called chitin, which helps ward off pesky nematodes – and if you have been following my articles, you know that microscopic nematodes are one of the worst pests of Hawaiian gardens, especially root crops. I always dust Crab Meal into my carrot and beets beds before lightly tilling and planting.
MINERAL FERTILIZERS (Natural, non-synthetic!)
Langbeinite NPK 0-0-22 is a naturally mined crystalline mineral that supplies the water-soluble sulfate form of three vital plant nutrients: potassium, magnesium and sulfurs. Nutrient-dense langbeinite is a popular fertilizer, especially where several nutrients are needed to provide adequate plant nutrition. Its advantage of having K, Mg and S all contained within each of its particles helps provide a uniform distribution of nutrients as farmers spread it through fields. Use sparingly.
Rock Phosphate NPK 0-3-0 is a calcium or lime-based phosphate rock mined from clay deposits that contain phosphorus and some calcium. I prefer the bone meals for this purpose, however, Rock Phosphate will last longer in the soil, so it is great for working into more semi-permanent planting beds like for asparagus. I also prefer the soft Rock Phosphate over the hard if you can find it like the one sold by Down to Earth.
Greensand NPK 1-1-5 comes from ancient sea beds. This high calcium fertilizer also contains iron, potassium, and other trace elements. However, the nutrient levels in glauconite or greensand products can vary depending on their source.
Soil Sulfur (or Soil Acidifier) NPK 0-0-0 is elemental sulfur and is used to lower soil PH, or make the soil more acidic. Use of this or Lime should only be done after testing the soil’s PH and knowing what PH the target crop requires or likes. I use Sulfur or Soil Acidifier (brand) in my Pineapple beds. Most vegetables like a 6 to 6.5 PH, which is a common enough soil PH here in Hawaii, however, a lower PH, like 5.0 promotes far less disease and better insect resistance for Pineapple growing. Work it into the soil well before planting.
Agricultural Lime NPK 0-0-0 Agricultural lime, is made from pulverized limestone or chalk. The primary active component is calcium carbonate. Additional chemicals vary depending on the mineral source and may include calcium oxide. It acts to “sweeten” or raise PH (make more basic or alkaline) in the soil very quickly. It will also remain in the soil raising the PH for a long time. It should only be used in moderation to raise soil PH. Also called Super Sweet.
Gypsum NPK 0-0-0 is a soil additive that helps to loosen compacted soil and promote root growth while enriching the soil with calcium and sulfur. Gypsum also improves soil structure. It has very limited use here in Hawaii with our generally fast draining soils except for hard compacted clay soil.
As a final note, I don’t recommend amendments/fertilizers like corn gluten meal, cottonseed meal, or soybean meal because they are usually contaminated with Glysophate, or Arsenic – and neither do I recommend blood meal because it is probably not organic and most likely is contaminated with hormones, antibiotics, etc. One use for Blood Meal, however, is as a Francolin or Chicken deterrent. Sprinkle around the perimeter of your garden, but not in it. The smell unnerves these birds and will usually keep them out of the garden.
Hopefully that should fill your soil amendment arsenal with plenty of options for your future veggie gardens!
For more info on everything from soils to irrigation to insect pests to the best veggie varieties for Hawaii, refer to my more than 25 articles on the BLOG page of Mauimistgardens.com.
Happy Gardening!
Dominic
mauimistgardens.wordpress.com 
This is the best educational article I’ve read about soil health. Thank you Dom!