Importance of good site characterisation

Within the manual Protocols for experimental plot sampling, handling and processing of cereals in field experiments(external link) by G.J. Rebetzke (, A. van Herwaarden, B. Biddulph, C. Moeller, R. Richards, A. Rattey and K. Chenu.

Good knowledge of the site and expected seasonal conditions based on a priori knowledge of long term weather trends are critical to planning and then interpreting field response data. Information such as starting conditions (e.g. soil type(s), soil moisture, soil nutritional status, soil diseases etc.) can and should be obtained for the experiment area to be used. Spatial site surveys using an EM38 meter (measures apparent electrical conductivity) have proven very useful in identifying uniform blocks to reduce residual (error) variation in large breeding experiments. Experiments that were thought to be poor have been reanalysed using EM38 measures as a covariate to remove much of the noise and reveal significant treatment differences. Long-term seasonal rainfall and temperature are also usually available, and should be used in planning for the need for irrigation, and sowing date when avoiding stress such as frost at flowering or hot, dry conditions through grain-filling.

An example of the type of data that may be obtained prior to sowing for the site Narrabri in NSW Australia is given below:

Narrabri (BoM station number for Narrabri West Post Office: 53030).

Latitude: 30.34�S; Longitude: 149.76�E; Elevation: 212 m; Mean annual rainfall: 644 mm;Mean annual maximum temperature: 26.7C; Mean annual minimum temperature: 11.6C.

Major soil types: Vertosol, Chromosol.

Target plant density: 100 plants/m2; Plot configuration and harvest: plot size: 9.75 m2; Row spacing: 32.5 cm; Distance between centre wheel tracks: 1.9 m; Number of rows: 5 (all rows are harvested); Plot length: 6 m of which 4 m are harvested.

Soil management: no-tillage and controlled traffic.

Three sites representative for the wide-range of conditions commonly experienced by growers in the different agro-ecological regions of the Australian wheat belt (Fig. 2).
 - File
Figure 2. Characteristics of the climate at three Australian sites: variability of monthly rainfalls (boxes mark the lower and upper quartiles, solid and dotted lines show the median and mean, and whiskers represent the 10th and 90th percentiles), and mean monthly minimum and maximum temperatures. Such data are critical in determining appropriate control of field experiment to ensure they are representative of the target environment. Data were sourced from link)

Other resources

Appendix 1.(external link) Text description of phenological scale, Zadoks decimal code (DC).
Appendix 2.(external link) Picture description of phenological scale, Zadoks decimal code (DC).
Zadoks JC, Chang TT, Konzak CF (1974) A decimal code for the growth stages of cereals. Weed Research 14(6),415-421. doi: 10.1111/j.1365-3180.1974.tb01084.x

Notes and troubleshooting tips


Download complete manual: Protocols for cereal field experiments_Nov2012.pdf

Health, safety & hazardous waste disposal considerations


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