What it is
WS-PA is natural phosphoric acid percolated out of sesame-stem charcoal. Sesame stems are rich in phosphorus, and burning them to charcoal then soaking releases it into water. Phosphorus builds the cell nucleus and drives cell division — it is the element that lets a plant switch from growing leaves to setting flowers.
On the Nutritive Cycle: WS-PA is the cross-over ("morning sickness") input. This is the sour, phosphoric nutrient a plant craves as it changes over from vegetative to reproductive growth.
When to use it
- Changeover period — dilute 700 ml : 20 L water and use alone to promote flower-bud differentiation, fertility, and yield.
- With water-soluble calcium, dilute instead at 1:1000.
- Apply when leaf color turns light or dark green; it also improves the sugar content of fruit.
Deficiency signs: flowering is suppressed, fewer fruits set, new leaves stay small and dark green, fruit skin thickens and turns acidic.
Materials
- Charcoal from sesame stems — 1 kg
- Water — 5 L
- Glass or clay jar, cloth bag, air tube, porous paper, rubber band
How to make it
- Char the stems. Burn sesame stems and put out the fire when large flames appear to leave charcoal, not ash.
- Bag 1 kg. Pack 1 kg of sesame-stem charcoal into a cloth bag.
- Soak in 5 L. Dip the bag in 5 L of water to dissolve the phosphoric acid.
- Aerate every 2 days. Blow air into the water through a tube — this helps the phosphoric acid dissolve.
- Wait ~7 days. Timing varies with surrounding temperature.
Signs it worked / troubleshooting
- ✅ Good: crude liquid drawn after ~7 days of soaking and aerating.
- ⚠️ Slow to dissolve = too cool → give it more time and keep aerating every two days.
- 🚫 Flowers won't set even after use = deficiency was already dormant inside the plant → treat earlier next season.
How to store
Cool, shaded jar with no direct sunlight, ideally 23–25 °C. Cover with porous paper so it can breathe.