Well you know sometimes you see a lot of small bridges that will have weight limit signs. I believe this is really for safety precautions. Keyword: SMALL bridge -
Due to some bridges being small, the materials and strength of the bridge may not can withstand a certain weight. The contents of the vehicle, axels, and wheels, all add to that weight. So there is a very good reason for that to matter.
I hope my somewhat, tied together answer provides just the information you need!
~Brooke❤️
This might refer to the phosphorus cycle.
Phosphorus cycle is a biogeochemical cycle that observes how phosphorus move through minerals, soil, water, and organisms. Typically, plants absorb phosphorus from the soil. And animals get phosphorus from the eaten plants. When these organisms dies, they decay and the phosphorus returns to the soil and inorganic matter.