As the members of a given generation age, their instinct of social conservation becomes stronger, which inevitably and necessarily brings them into conflict with the normal attribute of youthâinnovation. Other important theorists of the 19th century were John Stuart Mill and Wilhelm Dilthey.
Plants require more than just water and sunlight to grow. They also require many nutrients found in the soil. One of the most important nutrients required for plant growth is nitrogen. Nitrogen is used to build plant proteins and nucleic acids, including DNA.
A very small amount of organic nitrogen may exist in soluble organic compounds, such as urea, that may be slightly available to plants. The majority of plant-available nitrogen is in the inorganic forms NH 4 + and NO 3 - (sometimes called mineral nitrogen).