Plant physiology and nutrition link

[DavidCampen]

HYDROPONICS RESEARCH: USU CROP PHYSIOLOGY LABORATORY

Mineral Nutrition for Slipper Orchid Growers

https://www.msu.edu/~goddengr/public...blications.htm

https://www.msu.edu/user/harveyb/Fertilizers.htm

[DavidCampen]

The USU Crop Physiology link I listed above gives the following hydroponic solution macronutrient molar ratios:
N : 3.0
P : 0.5
K : 2.5
Ca: 0.5
Mg: 0.25
S : 0.25

The molar ratios of Mg to S are equal because they are using MgSO4 as the only source of both Mg and Sulfate. But I am wondering, does the amount of sulfate really need to be this high, wouldn't, say, a ratio of P to S of 10:1 be sufficient?

[WhiteRabbit]

thanks for sharing this info!

[Ray]

David, plants probably need even less sulfur than that.

If we look at the formula of the MSU RO orchid fertilizer - developed specifically for orchids from a very extensive array of studies - the weight percentage contributions of Mg and S are 2.0 and 0.09, respectively.