The Importance of Potassium
While most growers are aware that potassium is one of three macro nutrients (it’s the K in NPK), it has historically been considered the least important.
Not true, potassium plays a vital role in nutrient absorption, water movement throughout the plant (transpiration) and enzyme activity, all of which are critical processes in plant development.
Similar to calcium, pH, CEC and the presence of competing ions along with inadequate moisture in your soil will impact potassium availability. Unlike calcium, potassium is a mobile nutrient meaning what is already available in your plant will be transported to where it is most needed. With mobile nutrients, deficiencies typically show up in older parts of the plant first.
Potassium deficiency may result in stunted growth, reduced root mass, lower leaf striping or discoloration of leaf edges (although other issues can cause these types of symptoms also). By the time potassium deficiency is recognized, it may be too late to recover. Too much potassium can lock out the availability of competing nutrients such as calcium and magnesium. Organic sources of potassium include kelp, sulfate of potash (mined, low salt content), langbeinite (mined, high magnesium content), alfalfa meal and greensand (very slow release)
Calcium’s Role
Calcium is an essential element for almost all living organisms and plants are no exception. Plants need calcium for cell division and development. Calcium stimulates the protein channels that regulate uptake of other nutrients. Calcium promotes the development of pectins, increasing the plant’s ability to withstand disease.
Characteristics of your soil effect calcium availability including pH, CEC and the presence of competing ions. If your pH is in the ‘normal’ range, calcium can be readily available but if your pH spikes high or low you may notice a deficiency – even though there may be plenty of calcium in your soil, it cannot be absorbed by your plant. CEC is a factor of your soil components (the more organic matter and heavy material like clay, the higher your CEC) – the higher your CEC the greater the ability to hold and exchange
nutrients and minerals. Probably the most common cause of calcium deficiency is lack of water – without water, calcium ions will not be transported through the plant. This is easily corrected with good watering practices.
Calcium is an immobile nutrient meaning it is not transported to where it is needed (new plant tissue is usually the most needy), it stays where it first lands. This means that deficiency symptoms will be first seen in newer parts of the plant. Calcium deficiencies can be related to a variety of plant defects including leaf curling and necrosis, poor root development and blossom end rot. Calcium toxicity (too much) is not generally an issue directly although calcium can compete with other positively charged ions such as sodium, potassium, iron and magnesium.
Organic sources of calcium include lime, oyster shell, bone char, fishbone meal and bone meal (this is not a complete list).
Kelp Magic?
The popularity of kelp in plant fertilization programs is growing among both commercial and personal growers. So what is kelp exactly? There are approximately 10,000 known species of seaweed, primarily green, brown and red, all of which belong to the algae family. Of these, about 300 are classified as kelp. Kelp grows in shallow, cooler regions of the world’s oceans. Many grow rapidly, up to 1-2 feet per day, making them an excellent sustainable resource if harvested and managed properly.
Depending on the species, kelp may contain growth promoting hormones (auxins, gytokinins, gibberellins), trace elements, vitamins, amino acids, antibiotics and high amounts of soluble potassium. The most commonly used kelp species in North America is Ascophyllum nodosom, harvested from the North Atlantic basin.
A number of manufacturers tout other species as a ‘better’ kelp but I would be wary of this.
Kelp meal can be used as a soil amendment and liquid kelp extract as both soil drench and foliar sprays – our own studies along with other research indicate that liquid kelp may be more effective as a foliar spray. This is one of those products where more really isn’t better and, in fact, may be detrimental to plant growth, i.e., if you use too much kelp (particularly liquid kelp) your plants may suffer. We’re not sure why this is the case. It may be that too much available potassium is locking out other nutrients or too many growth hormones have a negative impact. So, start conservatively and build up your usage until you are happy with your results.
Humic and Fulvic Acids
I’ve talked about these before but, I’m a big fan... humic acid products are derived from leonardite which is a form of low grade coal. Leonardite deposits are found throughout North America and, like most mined products, will vary in characteristic and quality including humic and fulvic concentrations, ash content, the presence of heavy metals, etc. Humic acids are the final level of decay of plant and animal materials (think million year old compost). The term humic acid describes a family of molecules, the smallest of which is known as fulvic acid.
Humic acids stimulate microbial activity and bind to nutrient molecules. Binding molecules means a higher level of retention in soil (less nutrient leeching) and improved efficiency of plant uptake (your plant absorbs more of the available nutrients). Humic acid (dry form) can be used as a soil amendment and liquid forms as a soil drench (not recommended as a foliar feed). Fulvic acid is the primary uptake engine of the humic acid family and is particularly effective as a foliar feed. Humic acids are useful for both chemical and organic growers.
Organically Done is a Michigan manufacturer of organic fertilizers and soil amendments.
Our mission is to produce high-quality truly organic products that provide everything your plants need while being free of potential contaminating sources that are found in many of today’s “organic” alternatives – NOT ALL ORGANICS ARE CREATED EQUAL.
www.organicallydone.com
