01
Find the season’s nutrient target
Use your local recommendation — for example, 110–140 kg N/ha for first-crop japonica rice in central and southern Taiwan. It is a season total to split across basal, topdressing and panicle applications.
Fertilizer Calculator
Fertilizer Rate Calculator: How Many Bags Do You Need?
Fertilizer rates come down to one formula: nutrient needed (kg) ÷ the percentage on the bag = kilograms of fertilizer, then divide by the bag weight for the number of bags. For example, 120 kg N/ha with a 30-10-10 fertilizer is 120 ÷ 30% = 400 kg/ha — 20 bags of 20 kg. Pick a crop, enter your area and choose a fertilizer below.
Three inputs, instant answer
Crop rates fill in automatically; you can change them.
Result
Fertilizer needed
41.7 kg
About
2.1 bags（20 kg／bag）
This amount also supplies
Nitrogen (N) 12.5 kg
Phosphate (P₂O₅) 4.2 kg
Potash (K₂O) 4.2 kg
Note
Recommended range：11–14 kg／fen。Season total nitrogen, split across basal, topdressing and panicle; P and K by soil test.
Source：Agriculture and Food Agency: Crop Fertilization Manual (2024)
Results are season totals to split across basal, topdressing and panicle applications. Follow the product label and adjust for soil tests.
How It Works
How it works
02
Read the three numbers on the bag
They are the percentages of nitrogen (N), phosphate (P₂O₅) and potash (K₂O). 30-10-10 means 30 kg of nitrogen per 100 kg.
03
Nutrient ÷ percentage = kilograms
120 kg N ÷ 30% = 400 kg of fertilizer. Then check how much P and K that amount also supplies, so nothing is overdone.
Reference Rates
Recommended rates (per fen = 0.1 jia, season total)
- Rice — first crop (japonica, central/south/east Taiwan)
- N 11–14・P₂O₅ by soil test・K₂O by soil test（kg）Season total nitrogen, split across basal, topdressing and panicle; P and K by soil test.Source：Agriculture and Food Agency: Crop Fertilization Manual (2024)
- Rice — second crop (japonica, central/south/east Taiwan)
- N 9–12・P₂O₅ by soil test・K₂O by soil test（kg）Season total nitrogen; the second crop needs less than the first.Source：Agriculture and Food Agency: Crop Fertilization Manual (2024)
- Rice — panicle dressing only
- N 2.4–3・P₂O₅ by soil test・K₂O by soil test（kg）Based on 125 kg N/ha for the season with 20–25% at panicle stage; reduce if leaves are dark.Source：Agriculture and Food Agency: Crop Fertilization Manual (2024)
- Maize
- N 15–19・P₂O₅ 5–10・K₂O 5–10（kg）Based on a 6.5 t/ha yield; fields returning from fallow need more nitrogen.Source：Tan Z.W.: Maize fertilization, Taiwan Agricultural Research Institute
- Peanut
- N 3・P₂O₅ 5・K₂O 6（kg）Root nodules fix nitrogen, so keep N low; half the N plus all P and K as basal, the rest 25 days after sowing.Source：Liao Y.L. et al.: Rational fertilization of peanut, Taichung DARES
- Tomato
- N 15–24・P₂O₅ 10–15・K₂O 10–15（kg）Plus about 2 t compost per 0.1 ha; all P basal, N and K split into basal and three topdressings.Source：Chuan C.H. & Yang S.S., Hualien DARES Newsletter No. 65
FAQ
FAQ
Divide the nutrient needed by the fertilizer percentage to get kilograms, then divide by the bag weight. For 120 kg N/ha with a 30% N fertilizer, that is 400 kg/ha — 20 bags of 20 kg.
They are season totals, to be split across basal, topdressing and panicle applications.
One jia is 10 fen, and one hectare is about 10.3 fen (one fen is about 0.097 ha). The calculator converts units for you.
Treat it as a reference based on recommended rates. Follow the product label and adjust for soil tests, residual nutrients, variety and season.
