Seed Rate Calculation By: Sayed Mohammad Naim KHALID

Jan 2012 Kabul, Afghanistan

What is seed rate? Seed rate is the number of seeds to be planted in a specified surface or area to achieve an adequate stand. Seeding rates for cereals are still commonly given in figures of kilograms of seed per hectare or Jirib. Such rates are both convenient and useful to indicate the approximate quantity of seed that is required. Why understanding seed is rate important? The correct plant population is an important factor in maximizing yield of crops. It will help the overall health of the plant and vigor of the plant. To obtain the targeted population it is necessary not only to have quality sowing seed but also be able to accurately calculate seeding rates. It is surprising the difference a slight variation in seed size or germination makes to the seeding rate required to achieve a target plant density. Seed size, quality and germination vary between varieties, from year to year, from field to field and should be checked for each seed line to be used. How to calculating seeding rate?

Tools

1. Balance 2. Calculator 3. Paper and pen

Procedure

1. Know your target population goal or plants per hectare 2. Know the results of a germination test which provides an indication of expected plant

establishment in the field, 3. Know the expected plant establishment 4. Know Thousand Kernel Weight (TKW) for the seed to be planted. 5. Finally, use the following formula to calculate seed rate

𝑃𝑙𝑎𝑛𝑡𝑖𝑛𝑔 𝑅𝑎𝑡𝑒 = 𝑇𝑎𝑟𝑔𝑒𝑡 𝑝𝑜𝑝𝑢𝑙𝑎𝑡𝑖𝑜𝑛 (𝑃𝑙𝑎𝑛𝑡𝑠ℎ𝑎 )

𝑆𝑒𝑒𝑑 𝑝𝑒𝑟 𝑘𝑔 𝑋 𝐸𝑠𝑡𝑎𝑏𝑙𝑖𝑠ℎ𝑚𝑒𝑛𝑡 % 𝑋 𝐺𝑒𝑟𝑚𝑖𝑛𝑎𝑡𝑖𝑜𝑛 %

For example if the target plant population is 800,000 , the germination % is 0.9 and expected field establishment % is 0.75. In addition we assume that if the size of wheat seed is average so in 1 kg there will be 27500 seeds. Thus the result will be calculated as follow:

𝑃𝑙𝑎𝑛𝑡𝑖𝑛𝑔 𝑅𝑎𝑡𝑒 = 800,000

27500 𝑋 0.75 𝑋 0.9= 43 (

𝑘𝑔ℎ𝑎

)

We can also calculate the seed rate through the following formulas:

Seeds/ha = Target plant population (plants/ha) ÷ Germination % ÷ Expected field establishment %

Planting Rate (kg/ha)= Seeds/ha ÷ Seeds/kg

For example

Seeds/ha = 800,000 ÷ 0.9 ÷ 0.75 = 1185185 Planting rate = 1185185 ÷ 27 500 = 43 kg/ha