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Time to test your 2010 seed

It is more important than ever to know exactly how much seed you need to sow to achieve maximum results. Therefore calculating sowing rates is a must.

Sowing rate formula:

Sowing rate (kg/ha) = 1000 grain weight (g) x desired plants /m² ÷ germination percentage ÷ 100

Calculating thousand grain weights:

Calculating thousand grain weights can be extra work but it’s worth it. Table 1 below is from actual seed stored on an eastern Mallee farm and shows the difference grain weight can make to the sowing rate.

How to do your own grain weights:

1. Buy a reputable digital electric kitchen scale that weighs +/- 1g.
2. Use seed that has already been prepared for sowing (e.g. graded and pickled). The grain count can be made while the grader is running so that the amount of seed to be graded can be calculated to more accurately match the area to be sown.
3. Select a representative sample of seed e.g. 1L scoop.
4. Place some seed on an A4 sheet of paper near the edge of a table.
   Place an ice cream container on knees the under edge of the table.
   Using a skewer/knife, scrape 5 grains at a time over the edge of the table into the container.
   Do this 20 times (what equals 100 grains).
   Make a mark on the paper at the end of each group of 20. Repeat these groups of 20, 10 times and you will have counted 1000 grains.It doesn't take long and is an easy way to make/save money.
5. Place a small container on the kitchen scale and tare.
6. Tip in counted grains and record the reading—this is your thousand grain weight.

Calculating germination percentage:

The best way to test your seed germination is to simulate field conditions at sowing—cold and wet—to see how your seed will perform.

The worst simulation of field testing is in full sunlight on moist cotton wool on a warm windowsill!

BCG’s suggested DIY method is:

1. Half fill a container with moist soil
2. Place 100 seeds on the surface
3. Cover with 3 – 4cm of moist soil (normal sowing depth)
4. Place in the fridge or in a cool, dark place
5. Count the number of emerged seedlings after 12 days.

If the resulting establishment is less than 60 – 70% seek another seed source.

Note: ALWAYS conduct germination/vigour tests on spray topped grain before sowing as results are highly variable and unpredictable. Labels do not recommend use of this grain for sowing.

Old seed: Germination can deteriorate when seed is stored for a long period of time, seed treatments can also affect germination. There is nothing wrong with using correctly stored older seed but test its quality first.

Example of formula in use:
1000 seeds of Yitpi weighs40g, target plant population 150plants/m², approx establishment = 80%
Sowing rate (kg/ha) = 40 x 150/0.8/100 = 75kg/ha

Table 1: Example from actual seed stored on an eastern Mallee farm.