Ground Cover Supplement : GC Supplement - Water use efficiency
3 WATER USE EFFICIENCY GROUND COVER BENCHMARKING For the past 25 years grain production in some areas has struggled to meet the maximum water use efficiency proposed by French and Schultz. Is the bar too high or can we do better? By John Kirkegaard and James Hunt Average annual rainfall was 275 to 450 millimetres and 75 per cent of this fell in the growing season (1 April to 31 October). Indeed, it was French and Schultz who first proposed this date range as growing season rainfall (GSR) for their dataset. Soil moisture was measured at sowing in 15 to 30 centimetre intervals to a depth of 120cm and several times during the season. Rainfall was measured with a standard gauge on site; air and soil temperature, evaporation and radiation were all measured daily at the majority of sites. TABLE 1 Typical parameters for WUE traditionally used in the French and Schultz equation* Crop and region WUE (kg/mm/ha) Soil evaporation (mm) Wheat (southern and western) 20 110 Wheat (northern) 18 100 Barley (southern and western) 20 90 Canola (southern and western) 12 110 Chickpeas 12 100 Sorghum 25 150 * Potential yield (kg/ha) = WUE kg/ha/mm x (crop water use -- estimated soil evaporation (mm)) CROPS WERE NOT GENERALLY ACHIEVING THE MAXIMUM WATER USE EFFICIENCY. Watermark WHILE 1984 MAY not have lived up to the predictions of George Orwell, it did mark a pivotal point in broadacre crop production in Australia. In that year, the South Australian researchers Reg French and Jeff Schultz published their paper 'Water Use Efficiency of Wheat in a Mediterranean-type Environment -- the relationship between yield, water use and climate'. This crucial piece of work has helped establish production benchmarks for cereal and other crops across Australia and, 25 years later, it remains a cornerstone of research on water use efficiency (WUE). Yet in many situations grain crops are failing to achieve maximum water use efficiency, so is progress being made? The findings of French and Schultz Working in South Australia, the results of French and Schultz were based on wheat yields from 61 paddocks grown between 1964 and 1975. Soil types ranged from red-brown earths to calcareous sands. Sites were located within commercial paddocks and in trial sites and were selected to avoid sites or seasons with water loss by run-off or deep drainage.
GC Supplement - Wheat breeding
GC Supplement - Agronomy