Dr. S. H. Chien still correspond with us via emails after the High Reactive Rock Phosphate seminars that we held in Kuala Lumpur from 2014 to 2016. We include his recent write-up about another overlooked benefit of using high reactive rock phosphate such as Bayovar Rock Phosphate. Dr. Chien shares with us how to reduce MOP dosage for oil palm to help you save cost if you apply Bayovar Rock Phosphate as the P source.
The most important factor affecting the agronomic effectiveness of phosphate rock (PR) for oil palm production from the growth of young seedling to maturity is the reactivity of PR. The PR reactivity generally is measured by the solubility as measured by 2% citric acid (CA).
Table 1 shows the 2% CA solubility of different PR sources being imported to Malaysia and Indonesia for oil palm plantations.
It can be seen clearly that the solubility follows Bayovar PR (Peru) > BG4 (Morroco) PR > Egypt PR > Christmas Island PR. The reactivity accordingly is classified as very high, medium, medium and low for the four PR sources, respectively.
In a standard text book on oil palm by Hartley (1988), he stated that lower soil P levels could prevent the uptake and the use of available K. Data was extracted from a recent study Mohidin et al. (2015) using solution culture for oil palm seedlings as shown in Figure 1.
It can be seen clearly that both P and K uptake by oil palm seedlings (182 days) increased with increasing available P2O5 (solution P2O5 concentration).
In K uptake, the slope is 0.32 suggesting an increase of 0.32 mg K uptake could result from an increase of per unit of available P2O5.
Table 1 shows the available P2O5 (2% CA solubility) of Bayovar PR = 15.5%, BG4 PR = 9.0% and Egypt PR = 7%. Assuming the available P2O5 of PR is proportionally correlate with available P2O5 in solution culture, and K uptake by oil palm seedlings is proportionally correlate with that by mature oil palm, it could suggest that an increase in K uptake by oil palm from Bayovar PR over BG4 PR would be 0.32 x (15.5 – 9.0) = 2.08 units and over Egypt PR = 0.32 x (15.5 – 7.0) = 2.72 units.
This suggests that K rates for Bayovar PR could be at least 50% or less of that for BG4 PR and Egypt PR.
Of course, this is too simple in comparisons and subject to errors. Nevertheless, we could assume that the saving of K for Bayovar PR is lower, say, only 10% instead of 50%.
The price of MOP has increased from USD255/t to current USD$300/t, hence a minimum saving of USD$300 x 10% = USD$30/t in MOP use could be realized with Bayovar PR over other PR.
If an oil palm plantation company uses a minimum of 1,000 tons of MOP, the saving in MOP cost could be as high as USD$30 x 1000 = USD$30,000 with Bayovar PR.
In my opinion, this is possible even when we don’t have the actual data.
Hartley, C. W. S. 1988. The oil palm (Tropical Agriculture Series) 3rd ed. Longman Scientific and Technical. Harlow. Pp. 761.
Mohidin, H., M. M. Hanafi, Y. M. Rafii, S. N. A. Abdullah, A. S. Idris, S. Man, J. Idris, and M. Sahebi. 2015. Determination of optimum levels of nitrogen, phosphorus and potassium of oil palm seedlings in solution culture. Bragantia, Campinas, v. 74, n. 3, p, 247-254.
Authored By: Dr. S. H. Chien, 25th October 2018.
Published with the permission of the author.