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Organic Nitrogen Sources

There is nothing more vital than excellent organic nitrogen sources during the vegetative state. If you are growing synthetically, you can just grab any fertilizer and apply it with no extra thought. But, if you are growing organically, I hope everyone reading this is, you have a more difficult choice for organic nitrogen sources.

Nitrogen is the macronutrient directly related to overall plant growth. Read more about the macronutrients here. Nitrogen is directly responsible for leafy green growth. If you are growing heavy-feeding vegetables like tomatoes, peppers, eggplants, squash, melons, or anything like that, you need to make sure you have ample amounts of nitrogen. This nitrogen is what in turn supplies your plants with the required nutrients for optimal growth and fruit/vegetable production. Also, leafy greens like lettuce and spinach benefit from high nitrogen levels in the soil.

When it comes to organic nitrogen sources, we can separate them into three categories: animal-based, plant-based, or manure-based.

While each category provides nitrogen, some types act faster and last longer than others. For heavy feeding plants, try a combination of two or three of these nitrogen sources. For example, I always add a handful of plant-based nitrogen fertilizer to the planting hole when planting tomatoes. This fertilizer acts as an early-season nitrogen source for the plants and an animal-based Nitrogen source that acts as a slow-release fertilizer feeding the plant late in the season.

1. Animal-based Nitrogen Sources

Animal-based nitrogen sources are incredibly high in Nitrogen and the fastest acting. Initially, they quickly release nutrients into the soil and then slowly break down over time. If you are a vegan gardener or opposed to animal byproducts, this category is not for you.

Warning, these fertilizers can burn or damage small or delicate plants and their roots. Make sure to work the fertilizer into the soil, and do not simply sprinkle it on the soil and leave it there. I have the best performance from these fertilizers when I add them during cool season growing months such as the fall and winter.


Since some of these fertilizers can burn plants, I recommend applying this fertilizer to the soil before planting. If you must use it during the growing season, try side dressing or creating a liquid fertilizer and apply it foliarly.


  1. Fast Acting

  2. Slow-release of nitrogen source over time

  3. Most extended-lasting organic nitrogen source- Animal-based organic fertilizers can last for up to 12 months

  4. The highest source of organic Nitrogen


  1. Has the ability to burn or damage small plants

  2. Animal-based fertilizers have the potential to attract garden pests such as rats, opossums, raccoons, and other visitors

  3. Made as a byproduct from different industries that include animals. Therefore, vegan gardeners may be opposed to applying this to their garden,

2. Plant-based Nitrogen Sources

Plant-based fertilizers are an excellent fast-acting nitrogen source. Unlike animal-based nitrogen sources, these will not attract unwanted visitors to your garden. These tend to be less concentrated than animal or manure-based fertilizers, so be prepared to apply at a higher rate.

These fertilizers only work when the soil is warm, so it is best to apply them during the spring and summer. The reason they only work during these times is that they rely on members of the soil food web to help release their nutrients into the soil


  1. Less likely to burn your plants

  2. Hard to over-fertilize due to their less concentrated nature

  3. Will not attract unwanted visitors to the garden

  4. Balanced fertilizers that also supply small amounts of phosphorus, potassium, and Nitrogen

  5. Vegan


  1. Only applicable when the soil temperature is over 50 F

  2. Not as long-lasting as other nitrogen sources

  3. Since they are less concentrated, you will need to apply more to your garden to receive benefits

3. Manure-based Nitrogen Sources

Manure-based fertilizers are a great source of organic Nitrogen. When it comes to the concentration level, they are more concentrated than plant-based but not as concentrated as animal-based nitrogen sources. Manure-based nitrogen fertilizers are some of my favorites because you can create them at home. This fertilizer is the main reason I have chickens in my garden, and I create a closed-loop ecosystem right in my garden. I feed and house the chickens, and they reward me with fertilizer.


  1. Easily sourced

  2. Fast-acting and long-lasting

  3. Great nitrogen source to make teas and other foliar sprays with


  1. Must be composted for extended periods to kill disease-causing organisms

  2. Not vegan

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