Cities produce a lot of waste. What we consider to be biodegradable or compostable materials is Organic waste. Remaining food scraps, fallen trees, and cow poop are all examples of organic waste. When organic waste breaks down in landfills, it releases called greenhouse gases methane. Methane traps heat in the atmosphere and contributes to global warming. To reduce methane emissions, urban areas like Chicago, Illinois are trying to divert organic waste from landfills.
One way scientists have proposed to deflect organic waste is to use it as fertilizer on urban farms. Organic waste is a good potential fertilizer as it contains nutrients like nitrogen and carbon that the plant needs to grow. Researchers suggest that using organic waste on urban farms will allow cities to reuse waste and reduce chemical or mineral fertilizers.
Soil microorganisms such as bacteria and fungi break down organic materials for energy, making nutrients available to plants and other organisms in the process. Scientists should see the community of various microorganisms in the soil Soil microbiota. Because all microorganisms require energy, the soil microbiota is shaped by different energy sources in the soil. For example, some microorganisms prefer to get energy from sugar in plant materials, while others prefer to use the nitrogen found in animal fertilizers.
Researchers at the University of California, Davis and University of Wisconsin Madison wanted to know whether adding organic waste mixtures to the soil could alter the soil microbiome and improve crop growth compared to traditional mineral fertilizers. They produced four mixtures of organic waste collected in San Francisco, California. One was a liquid mixture of expired supermarket produce, one was food scrap compost, one was a mixture of plant-eating animal poop at a nearby zoo, and one was a dead plant-like garden compost. Researchers also included a control mixture, called nitrogen compounds, which contain the main ingredients of mineral fertilizers.
The researchers hypothesized that adding organic waste to the soil would increase the number and diversity of soil microorganisms compared to mineral fertilizers. They tested their hypothesis by cultivating tomato plants in greenhouse experiments. They applied a mixture of organic waste to the soil of local urban farms and placed the soil in a pot with tomato seedlings.
Researchers grew tomato plants for 75 days, then harvested and sampled the soil microbiota. They used a process of identifying microorganisms based on DNA. 16S rRNA Sequence. They measured the amount of carbon in bacterial and fungal cells.
The team found that soil treated with liquid food waste and animal poop had 127% and 120% more microorganisms than soil treated with urea. They discovered that microbial identity has also changed. For example, three of the four soils with organic waste mixtures contain more carbon cycling microorganisms; planutomyceota Bacteria than soil with urea. They concluded that the organic waste mixture maintained or improved the soil microbiota.
However, the researchers were surprised that the organic waste mixture did not change the microbial diversity or amount of microorganisms involved in soil nitrogen cycling. The team suggested that microbial diversity could still increase if the soil is fertilized for a long period.
The team then looked into the tomato plants. They determined the quality of the plant by measuring the height and weight of the plant, as well as the number and size of tomato fruit. They also analyzed the taste of tomatoes by measuring the soluble sugars of the fruit. They found that plants treated with organic waste had 15% to 75% smaller and 15% to 65% lower fruit yields than plants treated with urea. However, the tomatoes were all the same size, and some plants grown with organic waste had tomatoes with better taste. Researchers agreed that organic waste mixtures can improve the quality of certain crops, such as fruit taste, but further research is needed.
The team concluded that organic waste mixtures can support the healthy microbiota of urban agricultural soils. They proposed that farmers could use organic fertilizers as an alternative to mineral fertilizers such as urea. They suggested that reusing local waste would help bring more fresh food to urban communities.
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Source: sciworthy.com
