|Author:||Adcock, D. ; McNeill, A.|
|Book Group Author:||NA|
Components of the crop water balance were studied for a calcareous soil typical of a large proportion of the dryland cropping areas of South Australia. Soil water content was measured at intervals during the growing season in 2000 for wheat after a series of alternate crops (rape, medic pasture, vetch, barley and wheat) in 1999. No changes were observed in total soil water content below 70 cm soil depth, indicating the limit for extraction of water by crop roots. Drainage below this depth was not detectable. Plant available water in the root zone at sowing was significantly greater after rape (40 mm) than the other treatments but the difference was no longer evident 57 days after sowing. Total evapotranspiration (ET) was not significantly different for any of the treatments (mean ET=315 mm). Nevertheless yield (t/ha), and hence grain water use efficiency (WUE, kg/ha/mm), were significantly greater for wheat after rape (2.5; 8.0), barley (2.5; 7.9) and continuous wheat (2.4; 7.6) than after medic (2.2; 7.0) or vetch (2.1; 6.8). These values for WUE fall within the 25th percentile of WUE values recently obtained in a farm survey across the Mallee regions of New South Wales, South Australia and Victoria. Estimated loss of water via soil evaporation in 2000 averaged 101 mm whereas for the 2001 season it was considerably lower (64 mm). The major influence of rainfall and effective rooting depth on the dynamics of plant available water in soil is highlighted by the study. However, additional edaphic and environmental factors, including timing of rainfall events, soil fertility and phenological development of the crop are also critical when evaluating crop WUE, particularly in a semiarid environment.
available water, barley, calcareous soils, crop yield,evaporation, evapotranspiration, plant water relations, rape, semiaridclimate, soil depth, soil types, soil water content, swede rape, vetch,water balance, water use efficiency, wheat, Australia, New South Wales,South Australia, Victoria, Brassica napus var. oleifera, Hordeumvulgare, Medicago lupulina, Triticum, Triticum aestivum, Vicia, Brassicanapus, Brassica, Brassicaceae, Capparidales, dicotyledons, angiosperms,Spermatophyta, plants, eukaryotes, Hordeum, Poaceae, Cyperales,monocotyledons, Medicago, Papilionoideae, Fabaceae, Fabales, Triticum,Australasia, Oceania, Developed Countries, Commonwealth of Nations, OECDCountries, Australia, canola, Capparales, oilseed rape, Field Crops(FF005) (New March 2000), Forage and Fodder Crops (FF007) (New March2000), Plant Water Relations (FF062), Plant Production (FF100), SoilPhysics (JJ300)