Sewage treatment to the environment can lead to a buildup of nutrients, called eutrophication, which can in turn encourage the overgrowth of weeds, algae, and cyanobacteria (blue-green algae). This may cause an algal bloom, a rapid growth in the population of algae. The algae numbers are unsustainable and eventually most of them die. The decomposition of the algae by bacteria uses up so much of the oxygen in the water that most or all of the animals die, which creates more organic matter for the bacteria to decompose. In addition to causing deoxygenation, some algal species produce toxins that contaminate drinking water
Korean natural farming enhanced SI within 2 cropping cycles. KNF posits three primary stages of plant growth. Each stage requires a different balance of nutrients. In the growth phase, the plant extends its roots, branches and foliage. The key nutrient in this stage is nitrogen. KNF prefers the use of a preparation of fish amino acids for this phase. After the plant has reached sufficient size, the plant diverts its energy into making flowers to attract pollinators. The key nutrients in this stage are calcium and phosporous. KNF prefers the use of a preparation of fermented plant juice and other amendments for this