How do you tell the difference between a nitrigen deficiency...?

Question

..... and a magnesium deficiency, in plants what are grown in compost ?

and how are they rectified ????

Answer 1

When magnesium is deficient the leaves yellow between the veins. The oldest leaves may discolor or just shrivel & drop. Magnesium is necessary for photosynthesis so its lack produces chlorosis.

When nitrogen is lacking older leaves suffer first. They get an over all yellow color as chlorophyll diminishes giving them a uniform yellow cast becoming progressively whiter with extreme deficiency. Young leaves will be greener but small. Overall the plant will have short internode length in its stems so be stunted.

Foliar feeding can be used when insufficient fertilizer was used & when a quick response is wanted but it will not replace soil feeding only supplement it. It is best done early mornings when temperature is below 72F. However never spray on wilting or water stressed plants. Always water the plants well before either fertilizing the soil or spraying the foliage with supplements. Do not over apply fertilizers high in salts as this can increase water/heat stress.  It is better to use slow release or organic nitrogen sources to reduce potential injury.

An example of foliar feeding spray combo-

Fish (hydrolyzed) for nitrogen plus kelp or seaweed for magnesium. Diluted as directions indicate.

There are micronutrient specific sprays also like CalMag-Life, Spray-N-Grow, Mineral Matrix, Dyna-Gro, Earth Juice, etc.



I know you said these plants are growing in compost but it would be worth a pH test to be sure this wasn't part of the problem. If the pH is low the soil binds the nutrients despite adequate amounts being present. If this is the problem a foliar spray will relieve the problem temporarily but it will return.

Answer 2

magnesium = yellow leaves because it makes chlorophyll

nitrogen = makes protein so the plant can't grow without it