Field measurements of bare soil evaporation and crop transpiration, and transpiration efficiency, for rainfed grain crops in Australia – A review
Field measurements of bare soil evaporation and crop transpiration, and transpiration efficiency, for rainfed grain crops in Australia – A review
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DOI：
10.1016/j.agwat.2018.04.016
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发表时间：
2018-06
影响因子：
6.7
通讯作者：
M. Unkovich;J. Baldock;Ryan Farquharson
中科院分区：
文献类型：
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作者：
M. Unkovich;J. Baldock;Ryan Farquharson
澳大利亚的农业主要是在蒸发需求大大超过年降雨量的环境中种植作物。本文综述了作物蒸腾、裸地蒸发和作物蒸腾效率的田间测定方法。作物蒸腾量通常是根据蒸散量和裸地蒸发量之差计算的，然而，前者很容易测量，后者很难获得。对于小麦，我们发现只有19项研究测量了澳大利亚裸露土壤蒸发和作物蒸腾的临界水平衡参数，而对于其他作物的研究则少得多。根据对小麦的研究报告，平均38%的蒸散损失为直接土壤蒸发。其他作物的数据不足以确定它们是否相似或不同的小麦方面的相对贡献的Es和T的水平衡。尽管在实践中可能发生过这种情况，但我们找不到作物水分平衡的田间测量结果来证明近几十年来农艺措施的改进使作物蒸腾作用以牺牲倮地蒸发为代价而增加。尽管人们认为作物蒸腾效率主要是蒸汽压亏缺的函数，但文献中报道的作物蒸腾效率在不同作物中差异很大，即使在考虑蒸汽压不足之后。我们的结论是，更可靠的估计作物蒸腾效率将是非常有价值的计算田间生长的作物从地上部生物量测量的季节蒸腾，并提供了一个富有成效的途径，探索粮食作物的水分利用效率。
Australian agriculture is dominated by rainfed cropping in environments where evaporative demand greatly exceeds annual rainfall. In this paper we review field measurements of crop transpiration and bare soil evaporation under rainfed grain crops, and crop transpiration efficiencies. Crop transpiration is typically calculated from the difference between evapotranspiration and bare soil evaporation, however, while the former is readily measured, the latter is difficult to obtain. For wheat we found only 19 studies which measured the critical water balance parameters of bare soil evaporation and crop transpiration in Australia, and very many fewer for other crops. From the studies reported for wheat, on average 38% of evapotranspiration was lost to direct soil evaporation. Data for other crops are insufficient to ascertain whether they are similar or different to wheat in terms of the relative contributions of Es and T to the water balance. Although it may have occurred in practice, we can find no field measurements of the crop water balance to demonstrate an increase in crop transpiration at the expense of bare soil evaporation as a function of improvements in agronomic practices in recent decades.Although it is thought that crop transpiration efficiencies are primarily a function of vapour pressure deficit, transpiration efficiencies reported in the literature vary considerably within crops, even after accounting for vapour pressure deficit. We conclude that more reliable estimates of crop transpiration efficiency would be highly valuable for calculating seasonal transpiration of field grown crops from shoot biomass measurement, and provide an fruitful avenue for exploring water use efficiency of grain crops.