Effect of tillage practices and rainfall on dryland wheat water use efficiency
1997
Reeves, T.G. | Cass, A. | Hignett, C.T. | Mattiga Panomtaranichagul(Chiang Mai Univ., Chiang Mai (Thailand). Faculty of Agriculture. Dept. of Soil Science)
Project was carried out at Roseworthy campus, The University of Adelaide, South Australia during 1992 to 1995. Wheat, canola and faba bean were sown by direct drilling and conventional cultivation treatments. Four replications were used in a randomised split-plot experimental design. Soil water contents were measured through the growing season using a neutron moisture meter and time domain reflectometric methods. Soil properties were measured 1 month before harvest. Soil water evaporation was measured by a microlysimetric technique during some crop growth period. The soil water evaporation model was developed using field-measured soil water evaporation data, evaporative demand and soil water matric suction. A crop transpiration model was developed using meteorological and the field experimental data measured over the four years from 1992 to 1995. Experimental results showed that direct drilling induced better soil structure giving lower bulk density and higher aeration porosity of the surface and subsurface soil layers compared to conventional cultivation. Consequently, cumulative soil water evaporation from conventional cultivation treatment was higher than from direct drilled treatment due to poorer crop cover and degraded structure. Soil water evaporation and crop transpiration were substantially affected by crop growth and surface soil properties. In some years the surface soil structure varied as climatic conditions varied. The total amount of water used by the crop depended on rainfall distribution at each growth stage. The effects of tillage practices on grain yield and transpiration efficiency were not consistent because of the interaction between rainfall and tillage practices.
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