A guide to urban gardening, part 4: making natural fertilizer


Living in urban areas entails challenges like pollution. As per Rosalie Joven, gardener and resource speaker during the webinar ‘Basics to Urban Gardening’, if your home garden is located beside or near the roads, the application of natural fertilizers will help combat pollution (caused by cars and other pollutants) for your plants.

The previous articles talked about the advantages of urban gardening, different methods to achieve it, and steps in gardening. In the last part of the series, Joven discusses types of natural fertilizers and the process of making them. 

Natural fertilizer helps to:

  • feed the indigenous microorganisms,
  • improve soil tilth or the soil’s physical condition,
  • aerate the soil and retain soil moisture,
  • provide quality, better-tasting food with higher nutrient content, and
  • lessen production costs.

Making natural fertilizers

You can lessen your expenses by making your own natural fertilizer that is safer compared to the fertilizers that contain harmful chemicals. This will provide nutrients and proper growth for your vegetables.

To make an easy natural fertilizer, you’ll need 30% of carbonized rice hull (CRH), 50% of decomposed manure, and 20% of sawdust. Do not apply fresh manure as it contains bacteria that might harm your plants. It should be decomposed for at least one to three months, added with dried leaves. As per Joven, chicken manure is recommended as it has a higher organic matter.

  1. Indigenous microorganisms (IMO)

Among natural fertilizers, this is a primary component or the ‘mother’ of other fertilizers, said Joven. Indigenous microorganisms (IMOs) are made of moldy rice. This removes the foul odor of manure and other fertilizers. To create this, prepare your container: it can be a wooden box, bamboo pole, or plastic gallon. Let the cooked rice sit in the container and bury it upside down in a shaded area. If using a plastic container, cover it under a shade of trees or bamboo groove if possible. Wrap your wooden box or bamboo pole with plastic so it won’t get wet when it rains. Make sure to keep it out of reach of children.

After three days, get the container and it must have pink or light-colored molds in it. If dark molds develop, bury or throw it as it is harmful due to its disease-causing organisms. If this is the case, you’ll have to re-do the procedure again. Make sure to clean the materials and use another area to bury the moldy rice in. If successful, add muscovado sugar or molasses to the moldy rice, cover the container with a cloth or paper, and leave it in a cool, shaded area. Ferment it for seven days and it will turn into a dark juice. This can help you with soil fertility.

If dark molds appear, these must be discarded or buried as it may contain pathogenic organisms.
  1. Fish Amino Acid (FAA)

If you have intestines, gills, and bones of fish, you may use this method at home. This fertilizer is rich in nitrogen that can enhance your soil and that can be fed to animals. Just add them all in a plastic container, add the same amount of muscovado sugar or molasses and five tablespoons of Indigenous microorganisms (IMO), then mix it well. Conceal the container using a clean cloth, let it sit in a shaded area for 10-15 days, and collect the juice afterward. Mix two to three tablespoons of FAA in one liter of water and spray it on the plants, soil, or compost. Muscovado sugar or molasses will help lessen the bad smell of your FAA, so it is highly suggested to add it up.

  1. Fermented Fruit Juice (FFJ)

One example of this is fermented banana-papaya-squash (BSP). This fertilizer contains a high level of potassium and beta carotene that helps in plants’ growth. To make this, cut each fruit (banana, papaya, and squash) into thin slices and mix it thoroughly with water enough to moisten the mixture then add one kilo of molasses and wait for seven to ten days. An easy alternative to this is banana tea that is also packed with nutrients. Simply soak the banana peels into the water and leave it overnight or for a few days.

  1. Kitchen wastes compost

Among the other fertilizers, this is the easiest method to follow. Doing this can reduce your kitchen wastes and can help protect the environment. This can be practiced by filling a pail with kitchen wastes like fruit peels, vegetable peels, and gills of fish.

  1. Calcium Phosphate

This fertilizer allows the plants to have enough nutrients to produce flowers and fruits. Aside from providing additional nutrients for the plants, it also strengthens the plants’ ability to absorb more nutrients and water. Do this by gathering the eggshells from the eggs you consumed at home and roast them in a pan. Do not let all parts of it be burnt. “If using brown eggs, the white part should become light brown,” said Joven.

Roast and stir crushed eggshells in a pan until it turns light brown. Make sure not to overdo it.

Soak the eggshells in native coconut vinegar that should be at least three times the volume of your eggshells. Let it sit for a few weeks until you see that the eggshells are torn. A tip from Joven, you can also ask for free eggshells from the bakery where you buy your bread.

Do not cover the mixture too tightly as it might explode. Label the calcium phosphate or ‘caphos’ with the date it was formulated on and the date it will be ready for use.

Instead of chemical fertilizers, make use of your resources by creating any from these natural fertilizers that are safe and budget-friendly. 

Photos from Rosalie Joven.

Insights shared by Ms. Rosalie Joven during a webinar called ‘Basics of Urban Gardening’ hosted by 9 and beyond in partnership with Manila Bulletin and Agriculture Online, held last July 11, 2020.

Read more about farming and gardening at agriculture.com.ph.