How To Detect and Correct Soil Nutrient Deficiencies

If only your plants could tell you what they needed. A droopy jalapeño pepper plant might shout, “Hola Amigo, how about a little agua over here? Mucho Gracias!” 

Or An overcrowded row of shelling pea plants might politely request, “ A bit more room, if you please. Ah, that’s much better. Splendid, tip top, right-O! 

An hungry eggplant might break in with, “Hey wise guy, when are you gonna come through with that blood meal you owe me? I’m starving over here!”

Plants can’t speak, but they can still tell us when their soil is nutrient deficient.. Once we understand some basic plant sign language, an off colored leaf or sagging stem might as well be a clear call for help through a loudspeaker, or an interstate billboard.

Nitrogen Deficiency
Feeble growth and yellowing of leaves - especially in older growth. 

Nitrogen is the soil nutrient in highest demand and, and levels must be maintained continuously for healthy plant growth. As the major component of chlorophyll, Nitrogen what gives plants their green color. Add blood or fish meal, along with compost to the soil, to increase nitrogen levels.

Phosphorous Deficiency
Stunted growth, purple tinted plant tissue. Frail, brittle leaves and stems.

Phosphorous is the second most important soil nutrient. It is released by organic matter and mineral particles when the soil is warm, moist, and well aerated. Add bone meal or soft rock phosphate to the soil to increase phosphorous levels.

Potassium Deficiency 
Yellow veins between leaves, brown scorching and curling of leaf tips and edges, purple spots on undersides of leaves.

The third most important soil nutrient, potassium usually occurs naturally. Potassium, or Potash, is essential for plant cell functioning. Add wood ashes or green sand to the soil to increase potassium levels.

Calcium Deficiency
Stunted or dying plants, hooked appearance of new growth. Blossom end rot in fruiting vegetables, tip burn in brassica family plants, interior browning in celery and rosette types.

Calcium helps plant rootlets absorb soil nutrients, and also raises soil pH. Even when adequate levels are present in the soil, Calcium uptake is often poor in heavy, soggy soil. Always take steps to ensure good soil drainage, and add Dolomitic lime and gypsum to increase calcium levels in your soil.

Magnesium Deficiency
Leaves display green veins with yellowing in between. Yellowing begins in younger leaves, followed by older growth.

With a good cation exchange ratio, even low magnesium levels are sufficient to grow healthy plants. Add dolomitic limestone or epsom salts to increase magnesium levels. 

 Sulfur Deficiency
Yellowing of younger leaves, while older leaves stay green

The leaching action of rain sometimes depletes sulfur levels in deep, sandy soils. Add elemental sulfur or gypsum to the soil to increase sulfur - but use caution as it also lowers soil pH.