Urea is indeed UreaToo much of anything is a bad thing. Nitrogen...

Urea is indeed Urea

Too much of anything is a bad thing.

Nitrogen is needed by plants in the soil and when more of it is available, they'll use more of it and grow faster. Throwing too much into the soil, like anything, like drinking alcohol, is bad for it.

From a molecular perspective, it is fundamental to Cholorophyll which is needed for photosynthesis... See all the N's in the different Chlorophylls below...

	C55H72O5N4Mg	C55H70O6N4Mg	C35H30O5N4Mg	C35H28O5N4Mg	C54H70O6N4Mg	C55H70O6N4Mg

Which is why when there's leaching happening to waterways, algal blooms happen as it usually is the ion that is deficient in waters and soils due to the pure nitrogen molecules in the air being real stable and hard to break.

Unfortunately in the millions of years that plants have existed on earth, very few have evolved to get it from the over abundance in the air (peas, legumes, etc). Plants get it in ion form from the soil usually metabolised and broken up by symbiotic soil microbes.

Most farmers know this stuff above! So they ensure that there are a lot of microbes in the soil by giving them the conditions to thrive between harvests and mixing in nitrate type fertilisers in moderation.