Microbes produce an electromagnetic frequency; the more microbes, the stronger the signal, known as "quorum sensing." In layman's terms, this signal basically tells insects to stay away.
ក្នុង នាម ជា មួយ ឡែក, insects are attracted to free nitrogen ions. Most fertilizers consist of, ឬ បំបែក ចូល ទៅ ក្នុង, ions អាសូត ដោយ ឥត គិត ថ្លៃ.