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This article in AJ

  1. Vol. 72 No. 4, p. 689-692
     
    Published: July, 1980


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doi:10.2134/agronj1980.00021962007200040029x

Design and Testing of a Microlysimeter for Wetland Rice1

  1. V. S. Tomar and
  2. J. C. O'Toole2

Abstract

Abstract

Assessment of water loss as transpiration and evapotranspiration for each hour or for each day in the field is difficult because the available methods are either very expensive or inaccurate. This paper introduces a simple, sensitive, and accurate microlysimeter for wetland rice (Oryza sativa L.) fields.

The microlysimeter was designed and tested to measure transpiration and evapotranspiration in wetland rice fields. It consists of a poly-vinyl-chloride cylinder, sealed at the lower end and connected to a water reservoir/manometer through flexible tubing. A constant water level is maintained in the microlysimeter with a Mariotte system and water loss from the reservoir/manometer is measured. Total water loss as evaporation from free water surface in the cylinder and transpiration from canopy was measured as evapotranspiration. To measure transpiration, the cylinder was covered to stop evaporation from free water surface in the cylinder.

The microlysimeters were laboratory-calibrated and compared in the field with large square tanks. Water use pattern as evapotranspiration per unit land area was essentially the same with both the units. The microlysimeter is accurate even for time intervals as short as 1 hour and can be fabricated locally.

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