All you need to know about fertilizers

- Sep 19, 2019-


One of the finest things in life is sowing and waiting for a good yield. It hardly ever matters if one is a large scale farmer or just an average person enjoying gardening. The joy that comes along with soiling one’s hand and later enjoying a bumper harvest or simply some good yield is simply immeasurable. But like any seasoned farmer or gardener will tell you, you can’t expect good returns from whatever you plant without taking into account the value of good fertilizers.

Potassium Chloride

Otherwise referred to as Muriate of Potash or MOP, Potassium Chloride is certainly one of the most popular potassium used in agriculture. That explains why it accounts for as much as 90% of all potash based fertilizers in the world. Its nutrient composition is as follows:

Potassium – approx. 50%

Chloride – approx. 46%


MOP is rich in nutrient concentration. That is in fact, the sole reason why it is used in agriculture. The fact that it is always in demand also explains why it is a bit pricy when compared to other forms of potassium. The chloride content Potassium chloride can also be extremely beneficial where the soil in question is low in chloride. It helps to note that recent studies in different parts of the world unanimously agree that chloride can improve yields in several ways. One way it does this is by increasing disease tolerance or rather disease resistance in both fertile and semi-arid areas.

It should however be noted that in areas irrigation or soil water chloride levels are high, adding extra chloride can only cause more harm than good and result in toxicity. There is some good news though. This fear should not be a problem mainly because it is highly unlikely. It can only happen in extremely dry conditions. How so? Chloride is always removed from the soil by what experts refer to as leaching.

Application methods

As far as application methods of potassium chloride fertilizers are concerned, one only needs to focus on three main things.

  • Frequency and timing

  • Placement

  • Safe ratios and rates with seed

Timing always depends on the type of soil in question. In most annual plants where loam or red volcanic soil is used, application before planting is ideal. For other types of soils such as sandy or even clay, application can be done as much as twice before planting. In pastures, application can be somewhat different. Potassium chloride can be applied before the growing season. This can be done in early spring or in autumn or during both seasons.

For placement, application should be based on several factors. Crops like maize for instance, will require potassium chloride early in the season. One should therefore apply the fertilizer in the soil at a point where it can be easily accessed by rooting seeds.


Rates and ratios with seed

You can always learn more about fertilizer to seed ration by reading the instruction manual that comes along with your fertilizer. Not so with the rate. Note that when placed close to the seed during planting, two things can happen. The fertilizer can delay or prevent germination altogether. With that in mind, be keen with spacing during application.

Potassium sulphate fertilizer

It is also known as Sulfate of Potash or SOP. Used where special soil or crop needs exist, the fertilizer can also increase yields and turn formerly infertile areas fertile. The fertilizer is mostly used in for crops that are extremely sensitive to chloride and fertilizer burn. Pineapple, avocado and tobacco are just but some of the plants where the fertilizer can be used. The nutrient composition should be:

  • Potassium – approx. 41%

  • Sulfur – approx. 18%

Potassium nitrate fertilizer

It is also known as Saltpetre. Unlike the other two forms of potash already explained, Saltpetre is usually used in fertigation or foliar sprays. That is simply because it is water soluble. It can be used for crops that are extremely sensitive to chloride such as tobacco. Note that Potassium nitrate is a great oxidizing agent. It should therefore be handled and stored with utmost care. Its nutrient composition should be:

  • Potassium – 38% approx.

  • Nitrogen – 13 % approx.

NPK Fertilizer

Walk into any agro-vets store today and you certainly won’t fail to notice bags of fertilizers labeled as either NP fertilizer, NPK fertilizers or NPS fertilizers. It is important to understand what the letters and values on the fertilizers mean. N usually stands for Nitrogen while P and K stand for Phosphorus and Potassium in that order. S in NPS fertilizer stands for Sulfur.

  • Nitrogen – it is responsible for accelerating plant growth. It also increases food and fruit production. Being a component of Chlorophyll, which is the substance responsible for the green color in plants, nitrogen also plays a great role during photosynthesis. It also improves the quality of forage and leaf crops.

  • Phosphorus –Like nitrogen, it plays a big role during photosynthesis. It supports oil, starch and sugar formation. That is not everything though. There is the transformation of solar energy into solar energy, a process which is extremely important for plants. Phosphorous steps in as a catalyst. Then there is blooming and disease resistance, which are also crucial elements during crop growth. Phosphorus also helps a great deal in the two stages.

  • Potassium – The third essential nutrient in plants, potassium plays a role during photosynthesis. It also helps to improve fruit quality and build up proteins at the same time. Then just like phosphorus, it also helps to prevent diseases.

Liquid nitrogen fertilizer

Though not as common as the aforementioned types of solid fertilizers, liquid nitrogen fertilizer is just as important as they are. Farmers use it to apply reasonable amounts and portions of nitrogen to plants within a given growing season. Handling and application of the fertilizer play an important role as far as getting good yields is concerned. At the end of the day, it is only after one has understood how to handle and apply the fertilizer that he can confidently and comfortably use it without the fear or crop failure.

Use and application

The liquid nitrogen fertilizer behaves pretty much the same way all the aforementioned fertilizers behave. The difference in term of performance is minimal. There is however, no difference at well when it comes to solid nitrogen fertilizers. It is easy to understand why. Both liquid and solid nitrogen fertilizers feature urea as part of their composition. But when it comes to performance on how quickly the urea is absorbed into the soil, liquid nitrogen fertilizer takes the medal. That is because liquid urea is extremely volatile when it reaches the soil surface or when it is in the presence of adequate moisture. It works better where there is pH value that ranks at 7 and beyond. With such a pH value, it will easily carbonate the soil.

Leaf scorch and leaf tip burn are some of the setbacks one is likely to encounter after using liquid N. The two setbacks are different from each other but can be avoided using the same techniques and preventive measures. Of the two, leaf tip burn is more common. It occurs when urea is highly concentrated to toxic amounts on leaf margins and tips. The process happens through what experts refer to as rapid translocation. It can also happen because of the following reasons:

  • Mechanical leaf damage from low clearance sprayers

  • Nickel deficiency

  • Low metabolic rates from frost

To minimize both leaf scorch and leaf margin burn after spraying, consider the following:

  • Do not spray when there is frost or when there is forecast that there will be frost the following day

  • Always match N to moisture

  • Avoid using adjuvants


It is common to see farmers mixing liquid nitrogen with other chemicals. This is not bad. It should however be noted that manufacturers and sometimes chemical suppliers should be the ones dictating what can be mixed with liquid nitrogen fertilizers. Most manufacturers discourage the practice and state that it can only be considered where necessary. Most agree that liquid nitrogen fertilizer should not be at any point or for whatever reason be mixed with foliar nitrogen sources like propiconazole. To know what to mix with liquid nitrogen fertilizer and what not to mix with it, always refer for a compatibility chart which is available online. You can also request for one from an agro-vet store.

Point to note

Like you probably already know, liquid nitrogen is mostly applied to crops through spraying. That can only mean one thing –that you will need proper clothing when applying it. So invest in the right protective gear. Be sure to also follow the required safety measures when using solid fertilizers. Then like usual, store your fertilizers away from consumables. Store them too away from direct sunlight and far from children and pets.