Estimating yield

Spike numbers should be assessed when the flag leaf (final leaf) has emerged on main shoots (Z3.9) even though the spikes aren't out at that stage (This is the latest you can add nitrogen to improve yield). Make two counts in each of five selected crop areas (See methods below for row and broadcast planting).

Do not include any late regrowth tillers. Count all shoots that have nodes at this stage (the term ‘shoots’ always means both tiller shoots and main shoots) and that will give a good approximation of final spike number. Only water stress at later stages could reduce that number.

If planted in rows: Use a stick one meter long with a mark at 0.5 m to assess plant density. Put the stick between two rows in one of your pre-selected areas and count the seedlings on both sides of the stick. Make two counts in each of your five different areas and record the 20 numbers on the field sheets. Then work out the average of your 20 counts for the whole field. Seedling counts are done most quickly when there are only one or two leaves per plant (Z1.2 or 1.3). The presence of tillers later makes counting more difficult.

If broadcast: Count all seedlings inside a square with 0.5 meter sides. Multiply by 4 to get plants per square m.

1. Grain counts
   Count the number of grains in 10 spikes. Take the average.
2. Grain weight
   Make an estimate of grain weight based on growing conditions and variety (e.g., grain weight usually ranges from 33 to 48 mg. If growing conditions are good and the crop looks good, use a number at the upper end.)
3. Estimated yield
   Estimated yield (t/ha) = (Spikes per sq m) x (average # grains per spike) x estimated grain weight (mg)/10,000

See the yield calculator.