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Benefits of Composting: why you should start composting now!

April 27, 2025

There is less than 5% of residential food waste that is currently being composted around the world. To be exact, about 3.7% as of an April 2023 report. However, in contrast to the 1.3 billion tons of food wasted each year, this percentage doesn’t even scratch the surface. This food waste ends up in landfills, waiting to be decomposed to release methane, a potent greenhouse gas. So, what can we do in order to prevent this from happening?

Composting is widely known for its beneficial effects for recycling organic waste materials to create valuable soil amendment. Scientifically, it is the transformation of raw organic materials into biologically stable, humic substances suitable for a variety of soils and planet uses (Leslie, 2000). But if it’s so good, why aren’t more people composting their food waste? This could be due to a variety of reasons from perceived inconvenience, odor, and limited infrastructure, but most importantly, less and less people know of its actual environmental benefits. In this article, we examine the importance of composting and the science behind it. 

The process of composting involves the breakdown of a molecular structure into its elemental components–into simpler compounds or even atoms (Insam & de Bertoldi, 2007). There are two main phases in the process of composting: decomposition and stabilization. The final product is compost which is made up of carbon dioxide, water, minerals, and stabilized organic matter, which is essentially used as plant fertilizer to enrich the oils and support plant growth (Insam & de Bertoldi, 2007) Decomposition requires its very first step, the exothermic process, where it takes the waste and turns it into the form of heat simply by increasing the temperature in the mass (Insam & de Bertoldi, 2007). As temperature increases, thermophiles take over, continuing to the thermophilic phase. This stage becomes known as the active phase of composting, where degradable compounds and oxygen are consumed, pathogens and weed seeds are killed, and phytotoxins are eliminated (Leslie, 2000). Then we proceed to the two mesophilic phases. In these stages mesophilic organisms recolonize the whole waste pile and the curing phase begins (Leslie, 2000). Curing allows organic materials to continue to decompose, which are then converted to biologically stable humic substances. It is common practice in commercial composting to cure for 1 to 4 months, and for homeowner compost piles to cure for as long as 6 to 9 months (Leslie, 2000). Finally, the stabilization phase occurs after the temporary release of phytotoxins, where phytotoxicity is completely overcome and the final product is beneficial to plant growth (Insam & de Bertoldi, 2007).

Now you know how composting works, so what should you compost? You should compost greens–think nitrogen-rich materials like vegetable scraps, coffee grounds, and fresh grass clippings. These green materials have a lower supply of carbon relative to nitrogen (C:N), which means it has a faster composting process (Insam & de Bertoldi, 2007). For non-food waste, brown materials that are carbon-rich like dried leaves, cardboard, and straw. And if you’re worried about creating odor or attracting pests, avoid composting meat, dairy, oily foods, or pet waste. Wastes like these are more nitrogen rich, so it lowers the C:N ratio to less than 20:1, causing nitrogen to be lost to the atmosphere leading to foul odor (Insam & de Bertoldi, 2007). Lastly, make sure to keep it moist to speed up the decomposition process. Low moisture content impedes the composting process because it leaves your compost pile more susceptible to spontaneous combustion due to temperature (Insam & de Bertoldi, 2007). With patience and consistent practice, you’ll transform waste into nutrient-rich compost for your garden!

Sources Cited

Leslie, R. C. (2000) Composting: Art and Science of Organic Waste Conversion to a Valuable Soil Resource. Laboratory Medicine, 31(5), 283-290. https://doi.org/10.1309/W286-LQF1-R2M2-1WNT.

Insam, H., de Bertoldi, M. (2007) Chapter 3 Microbiology of the composting process. Waste Management Series, 25-48. https://doi.org/10.1016/S1478-7482(07)80006-6.

 

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  Timothy Durham was convicted of rape when a test showed his DNA genotype matched the DNA recovered from the crime scene. Eye witnesses testified that Durham was in a different state at the time of the incident, but he wasn’t exonerated from his 3000 year sentence until follow up DNA analysis showed that the preliminary forensic analysis used in the trial was misinterpreted (Thomas et al.). DNA testing serves an invaluable part in our criminal justice system, but it comes with complications and bias that can lead to wrongful convictions and misinformed juries.  

Background:

Forensic genetics aims to identify the origin of a biological sample. It can be traced back to Karl Landsteiner who discovered human ABO blood groups. With blood groups, suspects could be eliminated based on their blood type. For example, if a suspect had type A blood and there was type B blood left at the scene by the perpetrator, the investigators could rule out the suspect. Unfortunately, the reverse didn’t work. If the suspect and perpetrator both had the same blood type, it can’t be concluded that the suspect was guilty. Blood identifiers evolved into 8 distinct categories which improved the ability to eliminate suspects, but could only conclude that (if the system matched) it might be the perpetrator or this person might be related to the perpetrator (Jobling and Gill). The field evolved in the 1980s with the discovery of Minisatellites, lines of repetitive DNA that don’t encode proteins. Minisatellite patterns in DNA create what we know today as the DNA fingerprint, and it has a much higher accuracy rate than previous methods (Augustyn et al.). Around the same time, a breakthrough for victims of sexual assault was discovered. In the case of assault, bodily fluids of both the victim and the assaulter can get mixed. A process called differential lysis was created which could selectively increase the concentration of sperm in a fluid sample thereby allowing for accurate DNA testing (Jobling and Gill). Forensics evolved to use single-locus probe testing after several years because of its ease of interpretation. It looked at specific minisatellites that had high variability between subjects. This was the first DNA-based method to be used in a criminal investigation. Two murder homicides from several years apart were connected using DNA evidence. The evidence was then used to exonerate an innocent man, and the guilty party was found when he tried to evade mandatory DNA testing for all men in the small town. His guilt was then reinforced when the DNA profiles matched, and he gave a confession (Jobling and Gill). Finding DNA at a crime scene doesn’t guarantee that you’ll find a murderer. There are issues with non-pure samples and limited samples that make DNA work difficult, and accreditation of facilities and new techniques and take time (Jobling and Gill).  

Subjectivity of DNA Interpretation:

In a 2009 publication, the National Academy of Science discusses the possibility for subjective influence in lab based forensics. The interpretation bias happens in complex cases where, for example, there could be a mixture of DNA. A study published in 2011 looked specifically at this issue. A gang rape happened in Georgia, and the mixture in DNA from the case was used to prosecute one suspect after another suspect took a plea bargain to testify against him. With DNA mixtures, there are three possible conclusions: suspect excluded, suspect cannot be excluded, and inconclusive. If the suspect is excluded, it means that there’s little to no possibility that his DNA is part of the sample. If the suspect cannot be excluded, it means that there’s a possibility that his DNA is part of the sample. In the trial, the DNA examiners who knew the context of the case concluded that the suspect being prosecuted could not be excluded. The 2011 study gave the DNA evidence from this case and the DNA profiles of the suspects to 17 forensic examiners. These examiners had no context of the case, and they all worked independently. Of the 17, only 1 came to the same conclusion (suspect cannot be excluded) as the examiners who knew the context of the case. Twelve of the 17 concluded that the suspect who was prosecuted and convicted had no relation to the DNA found in the sample. Not only does this show that subjectivity occurs due to the context of the case, but the 17 examiners came up with different findings based on their past experiences meaning that not all DNA analysis is objective. Some organizations like the Scientific Working Group on DNA Analysis Methods say that quantitative statistical evidence should be presented with every categorical conclusion, but the US doesn’t require this (Dror and Hampikian).

False Positives:

There are two categories that cause wrongful identification in a DNA report: coincidental matches and false positives. Coincidental matches are DNA matches between two unrelated people. The probability of these matches is about 1 to 500,000 for white individuals and about 1 to 350,000 for black individuals. This small probability of coincidental matches makes people feel confident in DNA evidence. False positives, on the other hand, are matches between DNA and test DNA that result from issues in the forensics lab. There have been multiple cases of forensics labs accidentally switching victim and suspected rapist DNA which lead to convictions that were later overturned when the lab realized the error. There are also cases of misreading or misunderstanding a sample. In a case from 1993, a man was convicted of rape because someone interpreted a mixed sample of victim and perpetrator DNA as an individual sample. The conviction was again overturned. To prevent false convictions, retesting DNA is allowed, but it’s not an efficient solution. Many people are pushing for statistical information on the probability of false positives, so that the jurors can make accurate judgements based on DNA evidence (Thomas et al.).  

Conclusion:

DNA analysis is a useful tool for the criminal justice system, but subjectivity can be an issue in forensic testing. To combat wrongful convictions, there are organizations like The Innocence Project who use DNA testing to free the innocent, but reformed forensic testing standards should be put in place to prevent subjectivity and to ensure juries are correctly informed during trials. https://www.innocenceproject.org/    

Citation:

Augustyn , Adam, et al. “DNA Finerprinting.” Encyclopedia Britannica , 26 Apr. 2018, www.britannica.com/science/DNA-fingerprinting#ref153186. Dror, Itiel E., and Greg Hampikian. “Subjectivity and Bias in Forensic DNA Mixture Interpretation.” Science & Justice, vol. 51, no. 4, 2011, pp. 204–208., doi:10.1016/j.scijus.2011.08.004. Jobling, Mark A., and Peter Gill. “Encoded Evidence: DNA in Forensic Analysis.” Nature Reviews: Genetics, vol. 5, no. 10, Oct. 2004, pp. 739–751., doi:10.1038/nrg1455. Thompson, William C, et al. “How the Probability of a False Positive Affects the Value of DNA Evidence.” Journal of Forensic Sciences, vol. 48, no. 1, Jan. 2003, pp. 1–8., doi:10.1520/jfs2001171.