Fertility (soil) - Light and CO₂ Limitations

Light and CO₂ Limitations

Photosynthesis This is the process whereby plants use light energy to drive chemical reactions which convert CO₂ into sugars. As such, all plants require access to both light and carbon dioxide to produce energy, grow and reproduce.

While typically limited by nitrogen, phosphorus and potassium, low levels of carbon dioxide can also act as a limiting factor on plant growth. Peer-reviewed and published scientific studies have shown that increasing CO₂ is highly effective at promoting plant growth up to levels over 300 ppm. Further increases in CO₂ can, to a very small degree, continue to increase net photosynthetic output (Chapin et al., 2002 - Principles of Terrestrial Ecosystem Ecology).

Since higher levels of CO₂ have only a minimal impact on photosynthetic output at present levels (presently around 380 ppm and increasing), we should not consider plant growth to be limited by carbon dioxide. Other biochemical limitations, such as soil organic content, nitrogen in the soil, phosphorus and potassium, are far more often in short supply. As such, neither commercial nor scientific communities look to air fertilization as an effective or economic method of increasing production in agriculture or natural ecosystems. Furthermore, since microbial decomposition occurs faster under warmer temperatures, higher levels of CO₂ (which is one of the causes of unusually fast climate change) should be expected to increase the rate at which nutrients are leached out of soils and may have a negative impact on soil fertility.