Agricultural Improvement Station
The most important factors in assessing soil fertility are levels of nitrogen, phosphates and potassium, measured by electrical conductivity, as well as total soil organic carbon. In Taiwan, phosphate levels are often too high, so a method of regulation could be very helpful.
To understand the nature of soil better, we visited the Agricultural Improvement Center in Taoyuan. There, we learned that excessive phosphate levels due to over-fertilization is an increasingly common problem in Taiwanese soil, and that no regulation methods currently exist. To address this situation, we made sure that our biostimulators included agents that could curb the effects of any extra fertilizer present in soil. Additionally, the center suggested we pay attention to the most important indicators of soil fertility, such as nutrient levels, if we wanted to ensure health of both the microbiome as well as the crop. We made sure to integrate these tips into our project by generating a model that predicts changes in bacterial ratios based on changes in N, P, and K levels, and vice versa. We also designed a device that uses electrical conductivity as an indicator to project current N, P, and K amounts in soil.
NCHU, Professor Young
Bacillus subtilis is one of the most widely used phosphate-solubilizing biofertilizers in the world and is dominant among the phosphate-solubilizing bacteria in soil. Currently we are only able to add this biofertilizer, not inhibit it. A means of regulating Bacillus subtilis levels would help greatly in preventing excessive levels of phosphate in soil.
Our search for a phosphate regulatory agent led us to Professor Young of National Chung Hsing University. Young, renowned for his research in soil microbes, advised us to target the commonly-used Bacillus subtilis to control soil phosphate levels. Using an improved version of the peptide prediction model created by NCTU_Formosa 2017, we predicted numerous proteins with subtilis-inhibiting abilities, eventually finding peptides classified as bacteriocins, which we used as our biobricks. We then performed experiments using these bacteriocins to develop a model that describes the relationship between peptide volume and Bacillus subtilis inhibition, which can be used to precisely regulate subtilis levels in soil should they become too dominant.
Asia Agri-Tech Expo
Nobody has thought about improving crop productivity or soil health by directly targeting the microbiota. Most solutions focus on adding soil supplements without any mode of regulation. This concept presents a fresh take on an old problem and could really benefit the industry.
As our project matured we travelled to Taipei, where we attended the 2018 Asia Agritech Expo to confirm the usefulness of our concept. There we met with over one-hundred agricultural businesses from all over Asia. Many representatives were excited by the idea of regulating soil microbiotas, as well as the versatility of biostimulators that our model could support. One common suggestion for our project was to add a way of actually measuring soil health. After investigating commonly used ecosystem health indicators, we decided to use evenness, measured by calculating the Shannon index, to quantify soil integrity. The addition of this value allows users of our system to compare soil health before and after biostimulator use and helps determine the most environmentally friendly method of increasing crop yield.