water soluble fertilizer with humic acid

POSITION OF PENSHIBAO
Citric Acid, Amino Acids & Fulvic Acids       30%
Zinc (Zn) as Sulphate               0.3%
Boron (B) as Borate               1.00%
Nitrogen as Urea                 1.10%
Phosphorus (P) Water Soluble            7.20%
Potassium (K) as Phosphate             2.30%
Total Active Ingredients (min)            41.90%
Dissolving Agent                 30.00%
Water added to make 100%             28.10%
PH Value: 2-3        Max Biuret: 0.05        Density=1.18-1.20
II.THE PRINCIPLES IN THE FUNCTIONS AND PERFORMANCE OF PENSHIBAO
PENSHIBAO ( hereinafter referred to as PSB) is the most popular and widely used foliar fertilizer in China. It is the most prominent and effective multi-functional nutritive foliar fertilizer.
PSB's major active ingredients are extracted from natural plant materials. Only bio-active materials are extracted as chief components with the addition of trace elements required by plants.
As the concentration of its working solution is low, i.e. 1:10000 or 100 ppm, the quantity required for spraying an area of 1 hectare is only 75 ml of concentrate diluted in 750 litres of water. What are the substances in PSB which work with such low concentration when sprayed onto foliage.