LDD microbial starters (Por Dor): what each number does and how to use them

Por Dor (พด.) starters are sachets of selected microbes that Thailand’s Land Development Department (LDD) produces and hands out to growers. The number after “PD” tells you the job: PD.1 breaks plant waste down into compost, PD.2 makes a liquid bio-ferment, PD.3 helps control root and stem rot organisms, and the others each have their own task. Use the wrong number and you will not get the result you want.

This lesson sums up what each number is for, which microbes it holds, where to get it, and the recipes a home vegetable grower can actually use, based on LDD and provincial Land Development Station documents.

Where the PD starters come from

LDD developed PD.1 for compost between 1983 and 1992 and added other numbers later. The set in common use now is Super PD.1, 2, 3, 6, 7 and 9, plus PD.11 microbes and PD.12 biofertiliser; PD.13, 14 and 15 are more recent products.

Every sachet is living microbes, not a finished fertiliser. Its job is to speed up the breakdown or fermentation of materials you prepare yourself: plant waste, manure, molasses, fish, vegetables, fruit.

What each number does

Number	Used for	Main microbes or materials (per LDD documents)
Super PD.1	composting straw, leaves and plant waste	4 cellulose-digesting fungi, 2 actinomycetes, 2 Bacillus subtilis strains
Super PD.2	fermenting fresh material into liquid bio-ferment	yeast, lactic acid bacteria, protein- and fat-digesting bacteria, phosphate-solubilising bacteria
Super PD.3	compost carrying root and stem rot control organisms	Trichoderma viride and Bacillus subtilis
Super PD.6	ferment from food scraps for odour and wastewater	microbes for fermenting food waste
Super PD.7	herbal ferment to repel and deter insects	ferments bitter, astringent, hot and intoxicating plants
PD.9	making phosphorus available in mildly acid soil	phosphate-solubilising bacteria

LDD documents do not all list the same species for PD.2, because the formula has been revised over time, so the table gives groups. For PD.9, the Trang Land Development Station says it grows well at soil pH 4.5-6.5 and suits soil that is not below pH 5.

Where to get them

The main channels are the provincial Land Development Station and the village soil doctor volunteer (mor din asa). LDD runs training and hands out microbes to farmers across the country through this network, but how much is available and on what terms depends on each year’s budget and projects.

Phone the station nearest you first, ask which numbers they have, and say what you want to make. Staff can suggest the right number and a recipe that fits the materials in your area.

Recipes that work at home

PD.1 compost from plant waste. The LDD recipe is sized for about 1 tonne of plant waste (straw, leaves, grass clippings, rice husk), 200 kg of manure, 2 kg of urea and one PD.1 sachet dissolved in one large square tin (a “pip”) of water. Stir for at least 10 minutes, pour it evenly over the heap, keep moisture at 60-70%, and water and turn the heap every 7-15 days. In about 1-1.5 months you have compost. If you have no manure, good topsoil can stand in.

PD.2 liquid bio-ferment. In a 120-litre tank, dissolve 30 kg of molasses, 1 kg of rice bran and 40 litres of water or coconut water with two PD.2 sachets. Add 70-80 kg of chopped fish, golden apple snails, vegetables or fruit. Top up with water to cover, but keep the level at least 20 cm below the rim. Stir often, ferment for a month or more, then strain.

PD.6 food-scrap ferment. In a 120-litre tank, use 60-80 kg of food waste, 20-30 kg of molasses, 20-40 litres of water and two PD.6 sachets, and ferment for 15 days. Spray or pour it around rubbish areas at 2-5 litres per 20 litres of water every 3 days, or add 1 litre per 10 cubic metres of foul water.

If you would rather keep synthetic fertiliser out of your compost, see how to balance greens and browns in composting kitchen scraps.

Worked example: mixing PD.2 for a vegetable bed

LDD recommends a weaker mix of PD.2 ferment for vegetables than for rice: 30-50 ml per 20 litres of water, every 3-7 days. With a 5-litre sprayer:

1. Rate per litre of water = 30 ÷ 20 to 50 ÷ 20 = 1.5-2.5 ml
2. For 5 litres = 1.5 × 5 to 2.5 × 5 = 7.5-12.5 ml
3. Measure with a syringe or a medicine cup; do not guess by pouring from the bottle

If you use the rice rate (50-80 ml per 20 litres) on vegetables instead, you end up close to double the recommended strength.

Vegetables get PD.2 weaker than rice does: 30-50 ml per 20 litres of water. Measure every time.

Using several numbers together: high-quality organic fertiliser

LDD has a recipe that chains four numbers, in this order:

1. Grow up PD.2 first: 5 kg of molasses in 50 litres of water with one PD.2 sachet, lid on, in the shade for 3 days.
2. Pour one PD.1 sachet into 26-30 litres of that PD.2 liquid, stir for 10-15 minutes, and mix it through the raw materials, such as manure, bone meal and rice bran.
3. Heap it and cover it to keep moisture in. After about 3 days the heap warms to 45-55°C, then cools to the outside temperature in about 9-12 days.
4. Add one sachet each of PD.3 and PD.9, mix through, and leave for another 3 days.

The result carries root and stem rot control organisms from PD.3 and phosphate-solubilising microbes from PD.9. LDD’s rate for vegetables is 300 kg per rai (1,600 m²), broadcast when preparing the soil.

Common mistakes

• Using the wrong number. Sprinkling PD.2 on a dry straw heap instead of PD.1, or expecting PD.1 to stop root rot. Each number has its own job.
• Filling the ferment tank to the brim. LDD says to leave at least 20 cm below the rim; fermenting liquid foams and gives off gas.
• A dry or loose compost heap. The PD.1 recipe needs 60-70% moisture and a heap pressed down firmly. A loose heap dries out fast and the microbes cannot work.
• Mixing ferment too strong for vegetables. Use the vegetable rate, not the rice rate.
• Making PD.7 carelessly. The recipe includes several poisonous plants. Wear gloves, keep the tank out of children’s reach, and label it clearly.

PD starters are living microbes. Read the instructions on each sachet you receive: formulas are revised over time, and the Land Development Station will be more up to date than old leaflets.

The next lesson looks closely at Trichoderma, one of the microbes inside PD.3.

Sources

• High-quality organic fertiliser, LDD formula using PD starters (Thai) — Land Development Department
• Lesson plan: crop residue management by LDD, 2025 (Thai) — Land Development Department
• High-quality organic fertiliser mix and the microbes in PD.1, 2, 3, 9 (Thai) — Land Development Department
• Using LDD biotechnology products (Thai) — Suphan Buri Land Development Station
• PD.9: growing it up and application rates (Thai) — Trang Land Development Station
• Six decades of land development, lessons summary (Thai) — Land Development Department