Nutrition law of the minimum is considered an essential plant nutrient if the plant cannot complete its full life cycle without it. There are 16 essential plant soil nutrients, besides the three major elemental nutrients carbon and oxygen that are obtained by photosynthetic plants from carbon dioxide in air, and hydrogen, which is obtained from water. Plants uptake essential elements from the soil through their roots and from the air (consisting of mainly nitrogen and oxygen) through their leaves. Green plants obtain their carbohydrate supply from the carbon dioxide in the air by the process of photosynthesis. Carbon and oxygen are
Carbon dioxide standard hydrogen electrode. The nickel-containing enzyme carbon monoxide dehydrogenase catalyses this process. Carbon dioxide is colorless. At low concentrations the gas is odorless; however, at sufficiently-high concentrations, it has a sharp, acidic odor. At standard temperature and pressure, the density of carbon dioxide is around 1.98 kg/m, about 1.67 times that of air. Carbon dioxide has no liquid state at pressures below . At 1 atmosphere (near mean sea level pressure), the gas deposits directly to a solid at temperatures below and the solid sublimes directly to a gas above −78.5 °C. In its solid state, carbon dioxide is commonly