For a garden to thrive, it needs a combination of vital nutrients. The quantity of specific nutrients the plants require to thrive, determine which category they fall into; Macronutrients, Secondary, and micronutrients. Macronutrients are the ones plants need in the most significant amounts. These are also the nutrients notated on the label for your favorite fertilizer. The secondary nutrients are vital but required in smaller quantities than the macronutrients. These secondary nutrients are calcium, magnesium, and sulfur. All these nutrients play a different role, but they all seem to share one common trait; they leach easily from the soil.
Calcium is mostly related to the strength of the cell walls. Calcium deficiencies are rare in soil and are more often associated with hydroponic gardening. While calcium deficiencies are not ordinary, individual plants like tomatoes and peppers need additional calcium to ward off blossom end rot. Like nitrogen, calcium leaches quickly from the soil. That means if your growing in containers, prepare to supplement your plants with extra calcium. Plants with Calcium deficiencies usually display brown spots or markings on the leaves. Organic amendments that will provide calcium are Dolemite lime, Ground oyster shells, and even eggshells. I have had very little success with adding crushed eggshells to the soil. Recently I have started making water-soluble calcium.
Magnesium, as well as iron and calcium, is vital to photosynthesis. It almost acts like a switch that when flipped turns on enzymes that are vital to plant growth. Magnesium deficiencies are rare but are easily spotted. Plants with magnesium issues, the bottom leaves will begin to have streaks on the veins of the leaves while the remainder of the foliage stays green. These leaves will eventually turn red/ purple or brown but will usually remain attached to the plant. Nitrogen deficiencies behave similar, except the leaves fall from the plant. Since magnesium is absorbed by older leaves first, problems usually begin at the bottom of the plant and work its way up to the new growth. Organic amendments that will provide magnesium are Epsom salts, lime, compost, and composted animal waste.
Sulfur is required for plant amino acids and is directly related to plant proteins. Sulfur is needed to create chlorophyll and other enzymes. Sulfur deficiencies are rare when growing organically. The reason being, organic material usually stores sulfur. Chlorosis or yellowing of leaves is associated with Sulfur problems and often shows itself on new growth. Are you looking for an organic sulfur amendment? Try elemental Sulphur or compost. Yes, sulfur is a micronutrient, but plants need it in similar amounts as phosphorus. Maybe it should be the fourth macronutrients?
We learn about these nutrients to be prepared to solve issues that may arise within the garden. I have said it before and will repeat it. What is most important is that we build up the life in the soil. Focus on strengthing the soil food web. The billions of bacteria, fungi, and enzymes that make everything gardening and growing possible. Learn about each of these elements, and you will notice that you will rarely run into any of these deficiency issues. Just my thoughts. That’s enough reading, grow something!