Nitrogen for plants can come from many different sources:

• BLOOD MEAL. - Dry, inert powder made from blood that breaks down rapidly in the soil. ...
• FEATHER MEAL. - Derived from keratin, a protein that occurs in hair, hoofs, horns and feathers. ...
• POULTRY LITTER. ...
• ALFALFA MEAL. ...
• BONE MEAL. ...
• ROCK PHOSPHATE. ...
• SULFATE OF POTASH.
• Worm Castingsare the richest natural fertilizer known to humans. That's right: as little as a tablespoon of pure worm castings provides enough organic plant nutrients to feed a 6" potted plant for more than two months. Worm castings stimulate plant growth more than any other natural product on the market.
• light
• The obvious answer is that, like us, they see light. Just as we have photoreceptors in our eyes, they have their own throughout their stems and leaves. These allow them to differentiate between red and blue, and even see wavelengths that we cannot, in the far red and ultraviolet parts of the spectrum.

·        Plants Exhibit The Same Senses As Humans And See, Touch, Smell ...