Specialised Palm Fertilisers (Part 2 of 2)

Another possibility that palms may suffer from nutrient deficiency is that too high or low in soil pH may cause some nutrients to become unavailable to plants. There are pH probes and pH testing kits out there to find out.

Nutrient availability according to soil pH, with the optimum for plants in general being pH 6.2-7.3 (Source: https://ucanr.edu/sites/Salinity/Salinity_Management/Effect_of_salinity_on_soil_properties/Effect_of_pH_sodicity_and_salinity_on_soil_fertility_/)

For palms, the pH range for optimum availability of nutrients is even more narrower, between pH 6.5 and 7. Of course, there should also be organic matter in the soil. Soil organic matter (SOM) serves as a reservoir of nutrients, water retention, structure stability, cation exchange, regulate pH and bind SOM to soil minerals.

Here are some palm fertiliser products that I came across. Product names are changed to protect the innocent or otherwise.

1. "Migo" Palm "Food" - contains magnesium, iron and manganese. Other micronutrients are unknown. The shaker version is NPK 8-2-12 and Palm "Tree Food" version is NPK 8-4-8. 

2. "Rigo" Palm and Fern organic fertliser is 6-1-1-4 (4 refers to Sulphur as Sulphate, and also contain 1.3% Calcium). Contains blood and bone. In alkaline soil, Calcium carbonate  in the blood and bone will further increase the pH of the soil and reduce availability of N, P and most micronutrients. "Natural" sulphate of Potash is... mined from naturally occuring potash deposits in Europe. Not high anough potassium and other micronutrients it needed.

As a side note, a fertiliser could still be considered organic even if it contains mined potash (potassium). As a side side note, the name "potash" came from the phase "pot ash", which is how farmers obtain potassium a long time ago. They burn logs in clay pots to obtain its ashes, and spread it in their fields - hence the name potash.

3. "Higo" slow-release palm fertiliser has 15-15-15+2Mg plus "trace elements"... and works well with a "booster" liquid. If it is comprehensive enough then why would it need an add-on booster? 

4. "Sigo" is the one of the most complete and honest fertiliser suitable for palms and it is actually an Osmocote (slow-release) product, which says on the label that its for "Pots, Planters and Indoors". It clearly lists down the analysis, which contains nutrients that are essential for palms - K, Mn, Mg, and B.

Nutrient analysis:

N - 15.3%

P - 2%
K - 12.6%

S - 9.8%

Ca - 0.3%

Mg - 0.3%

Fe - 0.2%

B - 50mg/kg (0.005%)

Cu - 125mg/kg (0.0125%)

Mn - 150mg/kg (0.015%)

Mo - 50mg/kg (0.005%)

Zn - 38mg/kg (0.038%)

 

 Nutrient analysis of the Osmocote product - "Sigo"

A similar controlled-release fertiliser with very different nutrient analysis - "Bigo"

Turns out that palm do not need much phosphorous. Higher amount of micronutrient does not mean better for plants. Nutrients not absorbed by the plants and held by the soil will be leeched away. And that might pollute groundwater, streams and lakes.