Determining wheat yield

It’s important to adapt and revise your management strategies as the cropping environment, yield potential, commodity prices and input costs change.

Careful planning and management are essential for ensuring high yield. This applies to wheat as much as to any other grain.

High yield, in turn, implies a higher profit, as the production cost per ton of grain declines in proportion to the size of the yield.

Grain yield per hectare is influenced by:

  • The number of plants per hectare;
  • The number of ears per plant;
  • The number of grains per ear;
  • Individual grain weight.

These yield components and, ultimately, the grain yield, are determined during the three main development phases and growth stages.

It is possible, however, that a yield component that kicks in at a later growth phase may partially compensate for a sub-optimal factor at an earlier development stage (see table).

Factors influencing yield components

Set a realistic target yield for your cropping programme, taking into consideration all available resources. Target yield forms the foundation for crop management decisions.

You can make yield planning and other management decisions such as cultivar selection, fertiliser rates, herbicide and insecticide applications in light of target financial objectives.

The following factors should be considered when setting a target yield:

  • Experience: historical yield data of the past five years;
  • Plant-available water: sum of stored soil water at planting plus average growing season effective rainfall;
  • Long-term climate projections.

The risk associated with your selected yield target should be considered carefully. Profit is the compensation for taking risks, but be realistic!

The key management decisions to achieve target yields and maximise profits include the following:

  • Total farm planning including soil selection;
  • A well-planned crop rotation system;
  • Managing plant-available soil water;
  • Soil analysis for a relevant fertilisation and liming programme;
  • Setting a realistic target yield;
  • Applying effective soil cultivation practices;
  • Selecting the correct cultivar and using high-quality seed;
  • Optimal planting dates and seedling densities;
  • Appropriate planter speed and planting depth;
  • Controlling weeds, insects and diseases appropriately and at the correct times.

Source: Guideline: Production of small grains in the summer rainfall area (ARC-Small Grain).