MEASURING FORAGE CROP YIELDS
Equipment Needed:
- Length of alkathine 2.66m or slightly shorter to accommodate a joiner.
- Join the ends together to form a ring, this creates an area of 0.5m2.
- Empty seed bag
- Knife or other cutting instrument
- Hand-held scales
- Paper and pen/pencil
- Calculator
Number of samples per paddock = 5-6
Choose the sample areas from parts of the paddock which are representative of the entire paddock and throw the alkathine ring onto the crop.
- Any stem/bulb bases that fall within the ring circumference are
counted to be within the sample area (0.5m2). - Any leaf/branches that belong to a plant with a stem base that is outside the ring are to be excluded from the material being weighed.
- Remove all material by either cutting the crop down to about 1 inch from the ground e.g. for kales or pulling bulbs and leaves (ensuring dirt is removed) from swedes and turnips, put into bag and weigh.
Once all the samples have been taken, average the amounts and use the following formula:
E.g. Sample weights (kg) = 5.3, 5.6, 5.4, 5.9, 5.8;
Average weight = 5.6 kg/0.5m2
- Multiply by 2 to get kg/m
25.6 kg/0.5m2 x 2 = 11.2 kg/m2 - Multiply by 10,000 to convert to kg/ha (there are 10,000m2/ha)
11.2 kg/m2 x 10,000 m2/ha = 112,000 kg fresh material/ha - Multiply by appropriate DM% (see sensitivity table below)
112,000 kg fresh material/ha x e.g. 12%DM = 13,440 kgDM/ha
Sensitivity Table:
kg fresh matter 11% DM 12% DM 13% DM 14% DM 15% DM
112,000 12,320 13,440 14,560 15,680 16,800
A change in 1% DM can make quite a difference in how much is estimated to be in the paddock. If an exact DM% is required you can send a sample to a laboratory for assessment.