Climate data and yield variability

Climate information can be used to explore the year-to-year variability of an agricultural enterprise such as cropping. This example concentrates on three key climate parameters over a growing season - rainfall, maximum temperature and solar radiation.

The wheat yield, corrected for crop breeding improvements, at this 'sample location' has considerable variability over a 100 year period.

100 years of wheat yield statistics for 'sample location'

Which of the key climate parameters contribute most to this variability?

Seasonal accumulations of rainfall, maximum temperature and solar radiation over the same 100 year period have been analysed to show the percentage of occasions that various levels have been achieved. All three climate parameters show variability.

Analysis of yield as a function of rainfall and temperature

The analysis can be taken further to assess which combination of factors drives the yield variation. In the graph below, yield for each year is compared to the rainfall and maximum temperature accumulation values for that year.

It can be seen that whilst this graph looks somewhat noisy, a pattern can easily be discerned. At this location, best yields are obtained with adequate rainfall combined with a season where there is not excessive heat. Conversely, excessive heat and low rainfall combine to create a significant risk. Solar radiation can be explored in the same way, but is not included here.

Once the main weather variables that influence the crop yield have been determined, it is then possible to focus efforts upon understanding what drives changes in these variables. Is it El Niño or La Niña? The Indian Ocean? Cold Fronts? Understanding what drives the factors important for your crop is the first step in managing the climate risk.

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