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首页> 外文期刊>Agricultural Water Management >Comparisons of energy balance and evapotranspiration between flooded and aerobic rice fields in the Philippines.
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Comparisons of energy balance and evapotranspiration between flooded and aerobic rice fields in the Philippines.

机译：菲律宾淹水和好氧稻田能量平衡和蒸散的比较。

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摘要

The seasonal and annual variability of sensible heat flux (H), latent heat flux (LE), evapotranspiration (ET), crop coefficient (Kc) and crop water productivity (WPET) were investigated under two different rice environments, flooded and aerobic soil conditions, using the eddy covariance (EC) technique during 2008-2009 cropping periods. Since we had only one EC system for monitoring two rice environments, we had to move the system from one location to the other every week. In total, we had to gap-fill an average of 50-60% of the missing weekly data as well as those values rejected by the quality control tests in each rice field in all four cropping seasons. Although the EC method provides a direct measurement of LE, which is the energy used for ET, we needed to correct the values of H and LE to close the energy balance using the Bowen ratio closure method before we used LE to estimate ET. On average, the energy balance closure before correction was 0.72+or-0.06 and it increased to 0.99+or-0.01 after correction. The G in both flooded and aerobic fields was very low. Likewise, the energy involved in miscellaneous processes such as photosynthesis, respiration and heat storage in the rice canopy was not taken into consideration. Average for four cropping seasons, flooded rice fields had 19% more LE than aerobic fields whereas aerobic rice fields had 45% more H than flooded fields. This resulted in a lower Bowen ratio in flooded fields (0.14+or-0.03) than in aerobic fields (0.24+or-0.01). For our study sites, evapotranspiration was primarily controlled by net radiation. The aerobic rice fields had lower growing season ET rates (3.81+or-0.21 mm d-1) than the flooded rice fields (4.29+or-0.23 mm d-1), most probably due to the absence of ponded water and lower leaf area index of aerobic rice. Likewise, the crop coefficient, Kc, of aerobic rice was significantly lower than that of flooded rice. For aerobic rice, Kc values were 0.95+or-0.01 for the vegetative stage, 1.00+or-0.01 for the reproductive stage, 0.97+or-0.04 for the ripening stage and 0.88+or-0.03 for the fallow period, whereas, for flooded rice, Kc values were 1.04+or-0.04 for the vegetative stage, 1.11+or-0.05 for the reproductive stage, 1.04+or-0.05 for the ripening stage and 0.93+or-0.06 for the fallow period. The average annual ET was 1301 mm for aerobic rice and 1440 mm for flooded rice. This corresponds to about 11% lower total evapotranspiration in aerobic fields than in flooded fields. However, the crop water productivity (WPET) of aerobic rice (0.42+or-0.03 g grain kg-1 water) was significantly lower than that of flooded rice (1.26+or-0.26 g grain kg-1 water) because the grain yields of aerobic rice were very low since they were subjected to water stress. The results of this investigation showed significant differences in energy balance and evapotranspiration between flooded and aerobic rice ecosystems. Aerobic rice is one of the promising water-saving technologies being developed to lower the water requirements of the rice crop to address the issues of water scarcity. This information should be taken into consideration in evaluating alternative water-saving technologies for environmentally sustainable rice production systems.
机译：感热通量（ H ），潜热通量（LE），蒸散量（ET），作物系数（ K c ）和作物水分生产率（WP ET ）在2008-2009年期间使用涡度协方差（EC）技术在两种不同的水稻环境下（淹水和好氧条件下）进行了调查播种期。由于我们只有一个EC系统可以监视两个水稻环境，因此我们必须每周将系统从一个位置移动到另一个位置。总体而言，我们必须填补缺失的每周数据的平均值以及所有四个种植季节每个稻田质量控制测试所拒绝的那些值的平均50-60％。尽管EC方法提供了LE的直接测量值，LE是用于ET的能量，但在使用之前，我们需要使用Bowen比率闭合方法校正 H 和LE的值以关闭能量平衡LE估计ET。平均而言，校正前的能量平衡关闭为0.72+或-0.06，校正后增加为0.99+或-0.01。水淹和有氧田的 G 都非常低。同样，也没有考虑水稻冠层光合作用，呼吸作用和储热等其他过程所涉及的能量。在四个作物季节的平均水平上，淹水稻田的LE比有氧田高19％，而有氧稻田的 H 比淹水田高45％。这导致淹水田（0.14+或-0.03）比有氧田（0.24+或-0.01）的鲍文比率低。对于我们的研究地点，蒸散主要受净辐射控制。好氧稻田的生长期ET率（3.81+或-0.21 mm d -1 ）低于淹水稻田（4.29+或-0.23 mm d -1 ） ），这很可能是由于缺乏积水和好氧水稻的叶面积指数较低。同样，好氧水稻的作物系数 K c 显着低于淹水水稻。对于有氧水稻，营养阶段的 K c 值为0.95+或-0.01，生殖阶段为<1.00>或-0.01，0.97成熟期为+或-0.04，休耕期为+8或-0.03，而淹水水稻的 K c 值为营养期为1.04+或-0.04，生殖期为1.11+或-0.05，成熟期为1.04+或-0.05，休耕期为0.93+或-0.06。有氧水稻的年平均ET为1301毫米，淹水水稻的年平均ET为1440毫米。有氧田的总蒸散量比淹水田低约11％。然而，好氧水稻（0.42+或-0.03 g谷物kg -1 水）的作物水分生产率（WP ET ）显着低于淹水水稻（1.26） +或-0.26 g谷物kg -1 水分），因为需氧稻由于受到水分胁迫，其谷物产量非常低。这项调查的结果表明，淹水和好氧水稻生态系统的能量平衡和蒸散量存在显着差异。有氧水稻是为降低水稻作物对水分缺乏的需求而开发的有前途的节水技术之一。在评估环境可持续的水稻生产系统的替代节水技术时，应考虑这些信息。

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