Nitrogen (N) gets the growth show on the road. It's a building block for growing new stems and leaves, plus it is a necessary part of chlorophyll, which makes the leaves green and helps plants photosynthesize. Phosphorus (P) is needed for developing flowers, fruits, and root systems. Dinitrogen gas (N2), which makes up 79 per cent of the atmosphere, is by far the largest of the Earth's biologically available pools of nitrogen. Organic nitrogen stored in soils is the next largest pool, followed by the nitrogen stored in terrestrial biomass. The main pool of N in the soil is in the form of nitrate (NO 3), nitrite (NO 2) and ammonium (NH 4 + ). This phosphorus pool is comprised of primary and secondary phosphate minerals present in soil. Examples of primary phosphorus minerals include apatite, strengite, and variscite. The secondary phosphorus minerals include calcium (Ca), iron (Fe), and aluminium (Al) phosphates. Phosphorus is one of the major plant nutrients in the soil. It is a constituent of plant cells, essential for cell division and development of the growing tip of the plant. For this reason, it is vital for seedlings and young plants. Excess of P accumulating in the soil has increased the soil P pools. and soil P has become an environmental problem, causing the eutrophication of surface water systems, Two broad categories of soil P pools are inorganic P (Pi) and organic P (Org-P). Inorganic P (Pi) is considered a major source of available P in the soil.

In soil, both N and P are components of the organic matter and there are also inorganic pools. Is this what you wanted to know? The details are complicated