A comparison of evapotranspiration measurements of crop communities using lysimeters and assimilation chambers

Abstract

A sensitive weighing lysimeter which can be constructed largely of common materials is described. The mechanical structure of the balance is similar to that of McIlroy, but it has a different sensing system. It is suitable for short or long term measurements of evapotranspiration (E(t)). Measurements of E(t) for a wheat crop growing on the lysimeters were compared with E(t) measured with air-conditioned field assimilation chambers (enclosures) placed over the lysimeters and on other plots. The results indicate that the enclosure method is reasonable for comparative measurements of water use by plots with different treatments, particularly where water use cannot be determined with other methods. The enclosure technique is not affected by advection and is therefore useful for small plot work.