Szilas and O.K. Borggaard – Chemistry Department, The Royal Veterinary and Agricultural University, 40 Thorvaldsensvej, 1987 Frederiksberg C, Denmark
J.M.R. Semoka – Department of Soil Science, Sokoine University of Agriculture, P.O. Box 3008, Morogoro, Tanzania
Received: 21 June 2006 Accepted: 26 December2006 Published online: 25 January 2007
Abstract – “A compilation of all presently available agronomic data on the Tanzanian Minjingu Phosphate Rock (MPR) has shown to be a valuable tool for evaluating the interactions between tropical soils and MPR or Water Soluble P (WSP) sources. The effect of a delayed dissolution of MPR products compared to MPR with the yield response to WSP showed that, in the first 2 years, the average effectiveness of MPR is 74 and 94% of WSP respectively, whereas from the third year onwards the relative effectiveness is around 104%. From the analysis of the effect of soil properties on the yield response, it was found that low soil pH and low amounts of available P are the most favorable conditions for effective use of MPR. However, beneficial effects were also indicated on less acidic soils if they are strongly P deficient. MPR application seems to have superior effect on soil properties such as pH, exchangeable Ca and Al compared with WSP. The effect of MPR application on available P and Na OH extractable P is significantly lower compared with WSP but the difference seems relatively small. An estimation of the distribution of the cultivated area of Tanzania into four suitability classes for direct application of MPR seems to be a useful tool in the process of selecting target areas where direct MPR application should be promoted”.
Organic-phosphoric acid consists of:
About 70% of the citric acid is soluble and the rest of P is slowly released into the soil and constantly available in the soil. It is acknowledged that plants need continual phosphorus supply throughout its growth period to ensure a maximum harvest. This function cannot be found in chemical fertilizers such as superphosphate. Thus, organophosphates are proven to increase harvests compared to chemically treated phosphate fertilizers.
Plants absorb organic phosphates very effectively because the phosphoric acid is absorbed at a lower temperature compared to other phosphoric acid fertilizers. The table below contains some comparison between the organic hyper phosphate fertilizers at Minjingu.
The main component in Organic phosphate is Di calcium phosphate, which has a low solubility and does not condense. This reduces problems caused by unstable densities.
Why do Plants Need Phosphoric Acid?
When plants absorb appropriate amounts of phosphoric acid, nitrogen and potassium, they grow well and develop immunity to diseases and insects. Phosphoric acid is a crucial ingredient for plants to grow and reproduce.
While nitrogen and potassium aid growth, the excessive administration of potassium counters the fertilizing effect of magnesium and delays fruiting. During the early growth stages, excessive nitrogen causes a rapid growth rate and prevents the plant from maturing and moving into germination stage. It can also delay flowering and reduce the plants’ immunity to disease.
Plants require phosphoric acid mostly during the germination stage. Organophosphate reduces excessive nitrogen in the plants while phosphoric acid promotes plants to root vigorously and absorb nutrition. Organophosphate also prevents the growth of vines, promotes fruiting, and increases sweetness.
Calcium is an element that is usually used in Calcium containing fertilizers and tends to be washed away easily, however, Coral Calcium does not.
Coral Calcium does not rapidly neutralize soil acidity, however, when included in Organic phosphate, it promotes healthier soil and enhances safety for plants.
Coral – Calcium is sponge like in nature, it is porous and holds moisture. It promotes microorganisms in the soil.
The Calcium contained in Coral Calcium does not chemically react with other components in soil, making it is easier for plants to absorb.
Silicic Acid contained in Organophosphate is produced from organic Matter and thus does not harden and is easily absorbed. Calcium Silicic Acid, which is usually used as silicic fertilizer, is made from non- organic matter, and its solubility is deferent.
60% of the earth’s crust is made of Silicic Acid.
Silicic Acid enhances cation exchange capacity and increases soil fertility.
It was believed that Silicic Acid was only required by so called Silicic plants, however, this has been proven to be incorrect. Non Silicic Acid plants that lack Silicic Acid during their growth process tend to stop growing. If the plants are replenished with Silicic Acid, grow restarts making Silicic Acid indispensable to plants.
Silicic Acid rice plants produce silicate cytoplasm in the rice to strengthen the rice, protect it from diseases and insects, and strengthen the rice stalks.
Lack of Silicic acid decreases the effects of calcium, and increases the risk of disease.
Organic phosphate contains secondary as well as micronutrients including Magnesium, Boron, Ferric Oxide, and Sulfur.
The amount of micronutrients decreases after each harvest. The appropriate application of micronutrients will help reduce growth retardation due to continuous cropping. Previously, micronutrients were replenished naturally in the soil, however, due to deteriorated soil structures we require fertilizers. Although plants require only a small amount of minerals, balanced application will stimulate the reproduction of microorganisms in the soil, increasing soil fertility and reducing degradation.
The lack of micronutrients damage plant growth and reproduction increasing the risk of diseases. Moreover, the lack of micronutrients reduces the absorption of nitrogen, phosphoric acid and potassium in fertilizer.
In summary, the benefits of using Organic phosphate are as follows:
1. High Phosphorus content
2. Quick and slow release component
3. Citric soluble not water-soluble
4. Guaranteed minimum 50% citric soluble
5. Absorption starts at 4° Celsius
6. Very low fixation rate
7. Very low Cadmium level & other dangerous metals
8. Increases Cation Exchange Capacity (CEC) and helps microorganisms to reproduce & reduce soil degradation
9. Improves water and nutrient holding capacity
10. Acts as fertilizer and soil conditioner
11. Adds organic matter into the soil
12. Better metabolism of nitrate in plants
13. More phosphorous over the growing period
14. Stronger cell walls and therefore flavor enhancement
15. Resistance to fungi and mould attack
16. More upright stems & open leaves
17. Enhanced photosynthesis
18. More fertile and viable seed production
19. Increase in soil micro fauna
20. Longer shelf life of produce.
Farmers who have introduced Organic phosphate into their farming have realized that to enhance crop quality and production level, it is important to change previous farming methods, by ensuring the use of fertilizer that can restore degraded land and to continue to produce the following:
1. Water Field Rice Plants
2. Leaf Vegetables
3. Fruit Trees
4. Root Vegetables
5. Fruit Vegetables etc.
Looking for Citric Solubility
Many traders and users of P fertilizers mistakenly only measure P or P2O5% as an indication of effectiveness. Potash and Phosphate Institute recommends the correct method to measure how effective your phosphate fertilizer. P solubility level (known as citric acid soluble or the effective part of P) will determine how many kg/ton of P will be available to the plants in the near future. Minjingu Organic Hyperphosphate+ is the answer.
Organophosphate passes Potash & Phosphate Institute’s Standards.
“ A large number of Phosphate Fertilizer is available on the market. How does the agronomist select a suitable source?” Here are some points to keep in mind.
Look for Citric Solubility
While we all use P2O5 content as an index of quality it doesn’t mean much in terms of the potential effect of the Phosphate Fertilizer on crops. For example, consider a Phosphate Fertilizer with quite low total P2O5 of 25% and citric acid soluble P of 15%. 1,000kg Phosphate Fertilizer yields 16kg plant available P. By contrast 1,000kg of a material with 30% total P2O5 but citric acid soluble P of 10% yields only 13kg P.
Is it fine?
Second quality assessment criteria of Potash & Phosphate Institute:
“ The finer the material the greater the surface of area of the Phosphate Fertilizer exposed to the soil solution for dissolution. Most experts consider grinding so that 80% of the material passes through an 80 mesh (0.18 mm) sieve to be sufficient”.
With Minjingu Organic Phosphate,over 90% of the material will pass 0.15 mm sieve and not more than 10% will pass through 0.25 mm sieve.
Is it dry?
Third quality assessment criteria from of potash & Phosphate Institute:
“ Check moisture content of the Phosphate fertilizer. You get less ‘active’ ingredient (P/US$) if the material is damp/ wet and damp as it is much more difficult to spread in the field.”
Minjingu Organic phosphate is dry; moisture content of only around 5%
What does this mean to you?
In most cases to get the effectiveness of applying 100kg of Minjingu Organophosphate you will need at least 2 times the amount of other P fertilizers. Infact our recent trials in Southern Tanzania comparing the use of 200kg Triple Superphosphate (TSP) vs. about 80kg of Minjingu Organophosphate+ revealed that after 6 months of application, Minjingu Organophosphate yielded 20% more harvest.
First time users of Minjingu Organic phosphate are reminded to take into consideration the soil environment. Depending on the severity of soil conditions, it could take many months before soil environment is improved ( it also takes time to build up the P level in the soil).
Slow Release is Vital to increasing harvest.
Organic phosphate – Much more than just Phosphate Fertilizer
The slow release part of Organophosphate is a vital element that directly affects the quality and quantity of harvest.
Plants require constant supply of P throughout its growth period and if P is not available when needed, harvest quantity will be reduced. This function is not present in chemical phosphate fertilizers. Moreover, plants require a constant supply of P to allow better digestion of nitrogen fertilizer. If nitrogen fertilizer cannot be well absorbed, its remainder known as Nitrate Nitrogen is hazardous. Organic phosphate helps plants digest nitrogen effectively and reduces the unwanted excess of the “Undigested nitrogen.”