Neil C. Turner
Yields of dryland (rainfed) wheat in Australia have increasedsteadily over the past century despite rainfall being unchanged,indicating that the rainfall-use efficiency has increased. Analysessuggest that at least half of the increase in rainfall-use efficiencycan be attributed to improved agronomic management. Variousmethods of analysing the factors influencing dryland yieldsand rainfall-use efficiency, such as simple rules and more complexmodels, are presented and the agronomic factors influencingwater use, water-use efficiency, and harvest index of cropsare discussed. The adoption of agronomic procedures such asminimum tillage, appropriate fertilizer use, improved weed/disease/insectcontrol, timely planting, and a range of rotation options, inconjunction with new cultivars, has the potential to increasethe yields and rainfall-use efficiency of dryland crops. Itis concluded that most of the agronomic options for improvingrainfall-use efficiency in rainfed agricultural systems decreasewater losses by soil evaporation, runoff, throughflow, deepdrainage, and competing weeds, thereby making more water availablefor increased water use by the crop.
Key words: Crop management, fertilizer use, harvest index, modelling, rotations, tillage, transpiration efficiency, water use, water-use efficiency
Source: Journal of Experimental Botany 2004 55(407):2413-2425