With the exception of water, soil fertility is probably the single most important factor involved in producing good crops. In previous broadcasts I have been able to share about the nitrogen and phosphorous. These are probably the two nutrients, which are most often lacking in the soil, but there are also several other nutrients necessary for good plant growth. At least sixteen elements are known to be essential for plant growth. Plants obtain hydrogen from water, oxygen from the atmosphere and carbon from carbon dioxide in the atmosphere. Plants must obtain the other 13 essential nutrients from the soil in order to develop normally. These 13 nutrients can be divided into two groups, based on the amounts needed by plants.
The macronutrients or elements required in relatively large amounts include: Nitrogen, Phosphorous, and Potassium. The micronutrients or elements required in small amounts include: Sulfur, Calcium, Magnesium Boron, Chlorine, Copper, Iron, Manganese, Molybdenum and Zinc. Not only is it important that these 13 elements be present in the soil for plant use, they must also be present in varying degrees of availability, so that both the immediate and long-term needs of the crop are satisfied. In this broadcast I would like to concentrate on the final macronutrient, Potassium. Potassium is commonly called potash. This term referred to the fertilizer value of wood ashes. In the past and still today wood is commonly used to heat liquids in pots. Therefore, these ashes were referred to as pot ashes, and today we still refer to potash when discussing potassium.
Soils may contain from 12,000 to 60,000 kilograms per hectare of total potassium in the plow layer of a field. While this appears to be a very large amount, only 0.1 to 2 percent is readily available for plant uptake. Therefore, potassium is commonly lacking in the soil and needs to be applied as fertilizer. In this broadcast I would like to address three common questions; Why is potassium important and what does it do?; How much should I apply?; Are there any deficiency symptoms?
Why is potassium important and what does it do? Potassium is an important plant nutrient for several reasons. Potassium performs each of the following functions in the plant:
Potassium increases drought resistance of plants by regulating the gas exchange between the plant and the atmosphere.
Potassium is associated with stronger stalks and stems.
Potassium assists in more than 60 enzyme systems affecting metabolism.
Potassium assists in photosynthesis and conversion of sugars to starches and cellulose.
Potassium aids in movement of food within a plant.
Potassium increases protein, starch, and oil content of plants.
Potassium has been associated with resistance to diseases.
With all this activity, potassium has not been shown to be a part of the plant's organic structure. Instead, it acts as a policeman in the plant, keeping traffic ways operating efficiently. Researchers have dried and washed plant leaves and essentially all of the Potassium was removed by the washing, while leaving essentially all of the nitrogen and phosphorus behind in the leaf's structure.
I find the comparison of potassium and a policeman interesting. They both regulate functions. The potassium regulates the functions in the plant, while policemen regulate our functions. Sometimes we do not like to be regulated, but generally it is for our own good. I recently read a story about being regulated I would like to share with you.
It starts one windy spring day, I observed young people having fun using the wind to fly their kites. Multicolored creations of varying shapes and sizes filled the skies like beautiful birds darting and dancing in the atmosphere above the earth. As the strong winds gusted against the kites, a string kept them in check.
Instead of blowing away with the wind, they arose against it to achieve great heights. They shook and pulled, but the restraining string and the cumbersome tail kept them in tow, facing upward and against the wind. As the kites struggled and trembled against the string, they seemed to say, “Let me go! Let me go! I want to be free!” They soared beautifully even as they fought the imposed restriction of the string. Finally, one of the kites succeeded in breaking loose. “Free at last” it seemed to say. “Free to fly with the wind.”
Yet freedom from restraint simply put it at the mercy of an unsympathetic breeze. It fluttered ungracefully to the ground and landed in a tangled mass of weeds and string against a dead bush. “Free at last” — free to lie powerless in the dirt, to be blown helplessly along the ground, and to lodge lifeless against the first obstruction.
How much like kites we sometimes are. The Lord gives us adversity and restrictions, rules to follow from which we can grow and gain strength.
Restraint is a necessary counterpart to the winds of opposition. Some of us tug at the rules so hard that we never soar to reach the heights we might have obtained. We keep part of the commandment and never rise high enough to get our tails off the ground.
Let us each rise to the great heights our Heavenly Father has in store for us, recognizing that some of the restraints that we may chafe under are actually the steadying force that helps us ascend and achieve.
Source unknown.
This story illustrates how restraints set by God are in place to benefit us and to keep us grounded. I know people who do not know God and they are a lot like the kite without any restraints. They blow with the winds of the world, but never fly. This is because they find themselves in a constant state of crashing. This is because they have not found any direction or purpose in their life. Have you found direction and purpose in your life? Did you know that God has a plan for your life and he wants to share it with you?
When I think about how the potassium nutrient is very important in the life of the plant it reminds me of how God is important in my life. Potassium has been shown to be an essential nutrient for plants, but it is not really incorporated into the plant tissues. This is like God in my life. He is not in me in a biological sence, but he is still an essential element of my life. God has blessed me in so many ways and he wants to bless you. The greatest blessing is being able to have a saving relationship with God. But this relationship is only possible through God’s son Jesus.
Man’s relationship with God is what the Bible is about. An angel of the Lord said “Mary shall bring forth a son, and you shall call His name JESUS: for He shall save His people from their sins" (Matthew 1:21). Later Mary said, “My spirit hath rejoiced in God my Savior" (Luke 1:47). When our Lord was born, the angel said, “For unto you is born this day in the city of David a Savior, which is Christ the Lord" (Luke 2:11). Jesus said, “For the Son of man is come to seek and to save that which was lost" (Luke 19:10). On another occasion he said, “I am the door: by me if any man enter in, he shall be saved . . .” (John 10:9). Peter said, “Neither is there salvation in any other: for there is no other name under heaven given among men, whereby we must be saved" (Acts 4:12). Paul and Silas said to the prison guard, “Believe on the Lord Jesus Christ, and thou shall be saved, and thy house" (Acts 16:31). From these verses it is clear that God has one way only of saving men, and that salvation is the most needed and greatest gift to mankind. Whether you are young with a lifetime before you, or in your declining years, your greatest need is salvation, and the Lord Jesus Christ is the one and only Savior. He alone can deliver you from coming judgment and bring you to God.
I now want to answer the last two questions about potassium, starting with: How much should I apply? Like some of the other nutrients the best way on knowing how much potassium to apply is by testing the soil. I always recommend the farmer to soil test their fields every three years. However, not everyone has soil testing available. In these cases I make recommendations on the crop removal rates of potassium. I would like to share with you some crop removal rates of potassium for some of the major crops. I will start with corn. Corn removes 4.2 grams of potassium for every kilogram of corn grain produced. However, as I mentioned earlier there is a great deal of potassium involved in many plant functions other than just seed production. Therefore, it takes more potassium than just replacing what was removed. Lets stay with corn. Suppose you are trying to grow 10,000 kilogram per hectare corn. This crop would remove 42 kilograms of potassium, but to grow this crop you would need to apply 100 kilograms of potassium per hectare.
Soybeans (along with most all other beans) remove 19.9 grams for every kilogram of soybeans removed. If you are trying to grow 3,600 kilograms per hectare then this results in 72 kilograms of potassium being removed per hectare. However, like corn, soybeans need more potassium than what is actually removed to grow as a healthy plant. For this example, a farmer should apply 130 kilograms of potassium per hectare.
Wheat (along with most all other cereal grains) removes 4.2 grams for every kilogram of wheat removed. If you are trying to grow 3,600 kilograms per hectare then this results in 15 kilograms of potassium being removed per hectare. However, like corn and soybeans, wheat needs more potassium than what is actually removed to grow as a healthy plant. For this example, a farmer should apply 70 kilograms of potassium per hectare.
Lastly, I would like to talk about rice. Generally, rice does not need potassium fertilizer in my area. This is because rice is grown in rotation with other crops such as soybeans. The extra potassium fertilizer applied with the soybeans is enough to grow the rice the following year. The reason why rice does not need extra potassium is because potassium becomes more available under flooded soil conditions.
I have told you how much potassium to apply per hectare for several crops, but it can be hard to determine how much you are actually applying. Let me tell you a way of determining just how much potassium you are applying. Place a sheet on the ground and measure how many square meters the sheet is. Then apply potassium on the sheet at the rate you are trying to achieve. Then all you have to do is weigh the potassium fertilizer on the sheet and divide it by the square meters on the sheet. This will tell you the kilograms of potassium that were applied per square meter. The last step is to multiply the results by 10,000 to convert to kilograms per hectare. I also need to clarify one point. The fertilizer you are applying as potassium is not pure potassium. Therefore, you need to find out what percent of the fertilizer is actually potassium and base your application on this percentage.
Are there any deficiency symptoms? Potassium deficiency symptoms on cereal grains appear as a burning or scorching of the lower leaves. The burning begins at the tip of the leaf and continues down the leaf margin. Lower leaves are affected first because potassium in the plant is transported to the new upper leaves. Potassium efficiency in alfalfa appears as white or yellow spots on the lower leaves. Many other factors can affect the appearance of lower leaves so diagnosis based on deficiency symptoms is risky.
Potassium is one of the three macronutrients needed by all plants. It is involved in numerous plant functions and is considered to be an essential nutrient. Just as potassium is essential to plants, so is a relationship with God for us. If you do not now have this relationship and you desire to have it, then you can ask God to enter your life by saying the following prayer. “Dear Jesus, I believe that You died on the cross for my sins and that You arose from the grave. I now ask You to forgive me of my sins and to save my soul.”