Your options with organic fertilizers? As it turns out, they are indeed quite a few. For a gardener just starting out with concepts of organics, the variety of options can often be overwhelming.
A number of organic fertilizers exist with varying degrees of usefulness and ease of application and not all of them offer simple, straightforward guides to assist the user.
Those accustomed to precise instructions down to the last detail often encounter confusion with the seemingly haphazard “throw it on” techniques employed by seasoned organic gardeners.
The advantage here is that gardening does not require the sterile laboratory blending of fluids, measuring equipment, and data-rich charts detailing soil quality alongside plant health and viability.
It is more of an “artful science” wherein a wealth of knowledge, facts, and intuition play guiding roles alongside hands-on experience. The understanding of common organic fertilizers is reduced to knowing all of what organic materials each intends to offer to your soil and their “accessibility” for plant growth.
For this purpose, here is a compilation of some organic fertilizers and their values. NPK ratio (Nitrogen, Phosphate, and Potash) percentages and potassium are measured by weight while “availability” refers to immediate (fast release, available within hours), moderate (release in days), and slow (weeks).
We will also note the effects of the fertilizer on pH levels where relevant (acidity), “bonus” soil nutrients, and the nutrient known for calcium sulfate fertilizers. Some local garden centers may not stock these organic fertilizers so check out online retailers or those who specialize in organic gardening.
Don’t miss our top three favorites from this list of organic fertilizers at the end of the article!
Alfalfa meal:
2.5% N, 1% P, 1.5% K
Slow to moderate
Best known as a “hay” for animals, meal is one of the plant-based fertilizers. It is just ground up alfalfa that makes it compost faster in the soil. Enjoyed as a “hay” for livestock, it is quickly and easily turned into compost. Best tilled in as an early spring additive, well before the planting season. Find it here for sale and see pricing.
Bat guano:
8% N, 6% P, 1% K
Moderate to immediate
Among all the types of guano, Bat guano is the most common and has relatively fast uptake. It is applied during crop rotations which happen mid-summer or in late spring before planting. Bird guano has higher nutrition numbers, but seabird guano is only available in a few parts of the world.
Fish emulsion:
9% N, 0% P, 0% K
Immediate
This is a great additive for plants with low nitrogen levels or leafy plants that need a boost. As with all fertilizers, it will be tolerated differently among species as fish fertilizer tends to mildly acidic.
Cotton seed meal:
6% N, 3% P, 1% K
Slow
This is a slow-release fertilizer and is commonly used in regions that cultivate cotton. This is often preferred in the second half of the year which is a pre-winter mix. Applying it before cover crops or mulch will ready the soil for nitrogen uptake in the spring.
Corn gluten meal:
0.5% N, 0.5% P, 1% K
Slow
Corn gluten serves as an effective soil stabilizer for mid to late season winter add-ons and is particularly useful for pre-winter preparation.
Seaweed:
1% N, 2% P, 5% K
Fast
Seaweed is one of the most powerful organic fertilizers freely available along the coasts and an excellent source of zinc and iron. Seaweed is beneficial for cereal grains and other high potash crops.
Cow manure:
2.5% N, 1% P, 1.5% K
Moderate
Cow manure is widely used as an organic fertilizer due to its nutrient value. Similar to good compost, it does provide some level of nutrients. It may contain weed seeds, but is otherwise useful for gardeners. Avoid manure from dairies and other industries where the cattle receive a lot of salt.
Chicken manure (poultry):
3.5% N, 1.5% P, 1.5% K
Fast
Poultry-derived manure is another fast-acting organic fertilizer used in agriculture. It is mostly applied after harvest to be ready for a second planting later on.
Greensand:
1% N, 1% P, 5% K
Moderate
Literally ground up green limestone is full of rich nutrients as it’s a shallow marine sediment. The nutrient content varies greatly depending on the source of the sand.
Compost:
2% N, 1.5% P, 1.5% K
Moderate
The contents of compost are often variable as it depends on the raw materials. Most good compost is a roughly equal blend of the three primary macronutrients and helps create mildly alkaline soil. It is often applied prior to seeding, between plantings, or after the plants have matured. Rough compost can also be applied as mulch. Try worm composting or brewing ‘compost tea.’
Soybean meal:
3% N, 0.5% P, 2.5% K
Moderate
General adoption of this soybean meal additive will rely heavily on conditions, but maintenance applications will yield longer-lasting results.
Blood meal:
12% N, 1.5% P, 0.5% K
Fast
It offers a potent shot of nitrogen for plants in need of organic compounds, but it can be quite acidic. For blood meal to be effective, it is best applied to the soil surface after mulching and directly to the root zone.
Bone meal:
4% N, 20% P, 0% K
Moderate
Bone meal is appropriate where highly deficient soilquality requires severe amendments and restoration. It is also helpful to soils with excessive nitrogen, or those supplying nitrogen-burnt plants.
Feather meal:
12% N, 0% P, 0% K
Moderate
Most often, feather meal is applied pre-season to enhance soil health ahead of planting to provide a further nitrogen boost.
Fish meal:
10% N, 5% P, 4% K
Fast
Fast uptake of nutrients is why fish meal is a popular product to use. Legend has it that Native Americans would plant a fish at the base of their corn plants for a reason.
Our Top Three Picks from the List of Common Organic Fertilizers
Do you feel overwhelmed due to having too many options? No need to worry. We will focus on just three useful choices.
1. Compost
Compost is our first pick of organic products due to the astonishing change it brings to soil health and improves its structure and qualities. The additional nutrients provided to the soil are a bonus.
Moreover, compost is available to everyone. Urban gardeners can compost on their kitchen counters or keep a worm bin in the entryway. For gardeners with small yards, there is a wide selection of easy-to-use composters, some of which are even DIY-friendly.
Long before Pinterest existed, gardeners were making composters from pallets.
2. Manure
Let us combine cow and chicken manure because both provide unique advantages. Cow manure serves well as an all-purpose fertilizer because it can easily be worked into the soil’s surface layer, as well as incorporated into broad gardening spaces. Chicken manure serves as a more concentrated fertilizer that works well in small quantities in comparison to cow manure’s rich all purpose capabilities.
Manure greatly helps in adding nutrients to your garden, however, moderation and care do make a difference. Should you choose to compost chicken and cow manure on your own, be prepared for the aftermath of countless weeds! In that case, it might be simpler to buy prepackaged manure from a gardening store rather than rooting through the garden. Alternatively, you could go one step further and buy organic cow manures if that interests you.
3. Fish Meal
This is another one of the favorites on the list due to its ease of use and flexibility. There is no plant that doesn’t benefit from fish emulsion, and if you find one that does, it may not be worth trying to grow. One organic fertilizer does well in the veggie garden and flower garden and is just as useful for plants in containers.
Optimal soil and plant health can be achieved by trying all three organic fertilizers. This is achieved through the layering technique where compost is mixed into the soil, followed by adding manure during planting, and finally maintaining nutrition through regular application of fish emulsion every few weeks.