Development of Smart Weighing Lysimeter for Measuring Evapotranspiration and Developing Crop Coefficient for Greenhouse Chrysanthemum

The management of water resources is a priority problem in agriculture, especially in areas with limited water supply. The determination of crop water requirements and crop coefficient (K c ) of agricultural crops helps to create an appropriate irrigation schedule for the effective management of irrigation water. A portable smart weighing lysimeter (1000 × 1000 mm and 600 mm depth) was developed at CPCT, IARI, New Delhi for real time measurement of Crop Coefficient (K c ) and water requirement of chrysanthemum crop and bulk data storage. The article briefs about the design details including the assembly design with minimum soil disturbance, structural design and the operational design along with the performance characteristics of the developed lysimeter under different load conditions. The K c values of the chrysanthemum crop obtained from lysimeter installed inside greenhouse were K c ini 0.43 and 0.38, K c mid-1.27 and 1.25 and K c end - 0.67 and 0.59 for the 2019-20 and 2020-21, respectively which apprehensively corroborated with FAO 56 manual for determination of crop coefficient. The K c values decreased progressively at the late season stage because of the maturity and ageing of the leaves. Furthermore, the values of measured crop evapotranspiration (ET c ), were somewhat close to ET o values. However, the values of ET o were overestimated by 0.15 mm in 2019-20 and underestimated by 1.28 mm in 2020-21 then the values of ET c . The developed smart lysimeter system has unique application due to its real time measurement, portable attribute and capability of producing accurate results for determining crop water use and crop coefficient for greenhouse chrysanthemum crop