Bacteria, fungi, and worms are often associated with disease, disgust, and fear, but not for Dr. Shane Tutua, an organic farmer at the Zai Na Tina farm in Honiara, Solomon Islands. Dr. Tutua refers to these organisms as “soil engineers”, maintaining soil fertility. 

“The Significance of Soil Care”, a radio program that aired over the Solomon Islands Broadcasting Corporation (SIBC) highlights the pressing issue of low soil fertility and the scarcity of resources in the Solomon Islands. 

Due to factors that decrease soil quality and productivity, including strong weathering, nutrient leaching, and limited natural soil replenishment processes, the Solomon Islands confront substantial issues with low soil fertility, according to FAO’s The State of the World’s Forests 2020 report. According to the Asian Development Bank’s Country Partnership Strategy  for the Solomon Islands published in 2020, these problems are worsened by a shortage of resources, such as fertilizers and soil amendments, since many rural farmers do not have access to these crucial inputs for enhancing soil conditions.

According to Dr. Tutua, earthworms, centipedes, and millipedes are considered ‘soil engineers’ because they play crucial roles in maintaining and enhancing soil structure and fertility. Earthworms improve soil aeration and drainage by burrowing through the soil, which also allows for better water infiltration and root growth. As they consume organic matter, earthworms produce nutrient-rich casts that enhance soil fertility. While centipedes and millipedes contribute to the decomposition.

He also discussed the importance of the proliferation of soil organisms and soil bacteria, such as azotobacter, agrobacterium, flavobacterium, etc. In remote places where farmers lack access to or cannot afford inputs like fertilizers, biodiversity emerges as a strategic option to support or restore soil fertility and improve plant health.

Furthermore, he mentioned that dead plants, leaves, and legume plants are important in maintaining nutrients in the soil. According to him, there is a strong relationship between bacteria and legume plants. Bacteria provide nitrogen to plants, while plants provide sugar or energy to bacteria.

According to an article about the multiple benefits of legumes for agriculture sustainability by Fabio Stagnari published in the journal Chemical and Biological Technologies in Agriculture  in 2017, legume plants, such as beans, lentils, peas, and clover, are known for their ability to fix nitrogen from the atmosphere into the soil, due to their symbiotic relationship with nitrogen-fixing bacteria in their root nodules. This process enriches the soil with essential nutrients, reducing the need for chemical fertilizers. 

Additionally, legumes improve soil structure and water retention, which helps prevent erosion and maintain soil health. Their diverse root systems also promote soil biodiversity, making them valuable in sustainable agriculture and crop rotation.

Though not all bacteria are hazardous, individuals frequently associate the words “bacteria” and “worms” with negative connotations. Certain species, including humans, rely on them to survive.  Due to this, Dr. Tutuan advocates and educates on the need to promote soil organisms within agroecosystems as a nature-based and ecosystem-based approach to address issues related to soil fertility. Towards the end of the radio episode, he emphasizes how important soil biology and biodiversity are to the preservation and restoration of soil fertility.

References: 

Stagnari, F., Maggio, A., Pisante, M.(2017). Multiple benefits of legumes for agriculture sustainability: an overview. Retrieved from https://chembioagro.springeropen.com/articles/10.1186/s40538-016-0085-1

The State of the World’s Forests 2020.(2021). Food and Agriculture Organization of the United Nations. Retrieved from https://www.fao.org/state-of-forests/en/

Solomon Islands: Country Partnership Strategy. (2020). Asian Development Bank. Retrieved from https://www.adb.org/documents/solomon-islands-country-partnership-strategy-2012-2016

Article contributed by Thesa Elaine Mallo, ComdevAsia/CCComdev Intern