Nitrogen (N)

Nitrogen is one of the most important plant nutrients and plays a key role in the growth of leaves and shoots. It is a major component of proteins, enzymes and chlorophyll, and is therefore essential for photosynthesis.

Plants take up nitrogen mainly through their roots from the soil, where it occurs chiefly in the form of nitrate or ammonium produced by natural breakdown processes in the soil. Organic matter such as plant residues, garden compost or manure is decomposed by soil organisms, releasing nitrogen in a form plants can use.

Some plants, particularly legumes such as peas, beans or clover, can also draw on nitrogen from the air indirectly. They form a symbiosis with nodule bacteria, which fix atmospheric nitrogen and make it available to the plant.

An adequate nitrogen supply promotes strong, green growth and good development of the above-ground plant parts. Leafy vegetables and vigorously growing plants in particular have a high nitrogen requirement.

Typical signs of nitrogen deficiency are:

• ✔ pale green to yellowish leaves
• ✔ weak, slow growth
• ✔ early yellowing of older leaves

An excess of nitrogen, on the other hand, can lead to lush leaf growth while flower and fruit formation lags behind. Plants also become more susceptible to pests and diseases.