My last column was about knowing your plant’s diet. I focused on macronutrients then and this time I will focus on micronutrients. As I indicated previously, all nutrients are important, each has its specific purpose, and having the soil tested is critical for successful gardening.
Micronutrients, in order of need by most plants include iron, chlorine, manganese, boron, zinc, copper, and molybdenum. The nutrient cobalt is also needed, but the amount is not known. Research is being done on cobalt as well as the other nutrients. Micronutrients are critical in the photosynthesis process. Photosynthesis is where light from the sun, carbon dioxide from the air, and water from the roots produce simple sugars. Portions of the simple sugars are converted to carbohydrates, which are transported down to the roots.
Iron is essential to the plant’s photosynthesis process and maintenance of the plant’s chlorophyll. Chlorine is vital in the plant’s ability to resist disease, response to moisture stress, and developing stem strength. Manganese has a direct role in photosynthesis and transfer of energy through the plant. Boron is needed by the plant to develop new cells and form cell walls. It also aids in the transport of sugar and starches through the plant and of macronutrient potassium to the cells. Zinc is necessary to produce chlorophyll, carbohydrates, and growth hormones. Copper is important in formation of lignin in plant cell walls, which is major in the overall plant stem strength. Copper also affects the flavor and sugar content of fruits. Finally, molybdenum is essential in converting nitrates into amino acids within the plant.
You may notice how many of the words are used over and over. The nutrients work together in many cases. Several of the plant’s functions are influenced by more than one nutrient.
Now that we have covered both macro and micronutrients, I again want to stress why soil testing is critical. In the mid-1800’s, a German scientist names Justus von Liebig formulated the “law of the minimum.” The law states that “if one of the essential plant nutrients is deficient, plant growth will be poor even when all other essential nutrients are abundant.” Editor’s note: The law of the minimum actually originated with Carl Sprengel. The quote is not from either.
Thinking of the chain and its weakest link phrase, a crop can only be as productive (strong) as the least available (weakest) nutrient.
Okay, you are probably wondering where can you find these micronutrients? Depending on the micronutrient, they can be purchased at a full-service garden center or online. Products are available in liquid and granular form. Another all-around form of micronutrient delivery is compost. Compost, in addition to containing micronutrients, adds organic matter to the soil, improves drainage in clay soils, helps retain moisture in sandy soils, and provides microbial activity to the soil. Microbial activity is essential in converting both macronutrients and micronutrients into trace chemical forms available to the plant.
I hope you can appreciate macronutrients and micronutrients; your plant certainly does.
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