City waste could support urban farming
Researchers found that adding city waste products to local farms promoted a healthy soil microbiome and improved how tomatoes taste.
By Madeline Taylor
Science Worthy
March 17, 2025
Excerpt:
One way scientists have proposed to divert organic waste is to use it as fertilizer on urban farms. Organic waste is a good potential fertilizer because it contains nutrients like nitrogen and carbon that plants need to grow. Researchers suggest that using organic waste on urban farms could allow cities to reuse waste materials and cut back on chemical or mineral fertilizers.
Soil microbes like bacteria and fungi break down organic materials for energy, making nutrients available for plants and other organisms in the process. Scientists refer to the community of different microbes in the soil as the soil microbiome. Since all microbes require energy, the soil microbiome is shaped by the different energy sources in the soil. For example, some microbes like to get their energy from sugar in plant material while others prefer to use the nitrogen found in animal manure.
Researchers at the University of California, Davis, and the University of Wisconsin-Madison wanted to know if adding organic waste mixtures to the soil could change the soil microbiome and improve crop growth compared to conventional mineral fertilizers. They produced 4 mixtures of organic waste collected in San Francisco, CA. One was a liquid mixture of expired supermarket produce, one was a compost of food scraps, one was a mixture of poop from plant-eating animals at a nearby zoo, and one was a compost of yard clippings like dead plants. The researchers also included a control mixture containing the main ingredient in mineral fertilizers, a nitrogen compound called urea.
The researchers hypothesized that adding organic waste to the soil would increase the number and diversity of soil microbes compared to the mineral fertilizer. They tested their hypothesis by growing tomato plants in a greenhouse experiment. They applied the organic waste mixtures to soil from a local urban farm and put the soil into pots with tomato seedlings.
Read the complete article here.
Source: https://cityfarmer.info/city-waste-could-support-urban-farming/
