A field experiment was conducted for three consecutive years 2015-17 during the summer season at the experiment farm of ICAR-Central Arid Zone Research Institute, Jodhpur to determine the actual evapotranspiration of clusterbean [Cyamopsis tetragonoloba (L.) Taub.] using mini-lysimeter by imposing different levels of irrigation based on cumulative pan evaporation (CPE) 50 mm irrigation at 100, 80, 60 and 40% of CPE. Three year averaged actual crop ET was observed 686, 554, 454 and 340 mm under 100, 80, 60 and 40 % irrigation levels, respectively. The highest crop ET was recorded under 100% followed by 80, 60 and 40 % irrigation levels. However, maximum water productivity (0.35 kg m-3) at 80% irrigation level, while the lowest (0.21 kg m-3) was observed at 40% irrigation level.The results also indicated that to achieve maximum water productivity, crop ET would need to be at least 554 mm and the crop can save 19.2% (132 mm) of water with a compromise in yield reduction by 10.4% (225 kg).

Renewable energy generation has gained much more importance in India than ever before. Photovoltaic (PV)-based electricity generation shares a major portion of renewable energy generation in India. PV-based electricity generation requires land of about 2 ha per MW of installation. Since both food and energy are required for human civilization to progress, here a concept of integrating PV-based electricity generation and crop production from a single land unit is designed and developed, which is known as agri-voltaic system. Such systems of 105 and 25 kW have been established at ICAR-Central Arid Zone Research Institute, Jodhpur, and its regional station at Bhuj, respectively, with a land requirement of 29 m2 per kW. Rainwater harvesting system from top surface of PV module has been designed and developed. The harvested water is expected to provide supplemental irrigation of 43 mm in 0.76 acre land on which 105 kW system has been established. Suitable crops for agri-voltaic system have been identified, which generally does not attain height not more than 50 cm during its crop growth period. Few of the selected crops are Vigna radiata (moong bean), Vigna aconitifolia (moth bean), Plantago ovata (isabgool), cuminum cyminum (cumin), etc.

This study used hierarchical cluster analysis (HCA) to delineate the spatial patterns of monthly, seasonal and annual rainfall by clustering 62 stations in the western arid region of India based on a 55 year (1957–2011) data set. The statistical properties of clusters were computed and box–whisker plots plotted. Furthermore, the relative influence of three geographical factors (longitude, latitude and altitude) and five statistical parameters (the mean, standard deviation (SD), co‐efficient of variation (CV), and maximum and minimum rainfall) on mean rainfall was investigated using principal component analysis (PCA). The use of HCA resulted in four rainfall clusters geographically located at a distinct position. Cluster I, characterized by the lowest mean rainfall and highest CV, was located in the western portion, whereas mean rainfall was the highest for cluster IV situated in the eastern portion. Box–whisker plots revealed a slight skewness, although the monsoon and annual rainfall followed a normal distribution. The PCA results indicted two to three significant principal components (PCs) with eigenvalues > 1. In four clusters, two PCs explained the major variance, ranging from 69.41% (June) to 91.83% (August) in monthly rainfall, from 63.62% (monsoon) to 93.30% (post‐monsoon) in seasonal rainfall, and from 71.48% to 90.73% in annual rainfall. In monthly and seasonal rainfall, first PC 1 is termed the “mean rainfall component”, which has strong to moderate associations with longitude, and is equally opposed by the CV. These findings are vital for planners and decision‐makers to formulate strategies to manage unusual rainwater quantities.

In view of future requirement of both energy and food, agri-voltaic system (AVS) has been proposed as a "mixed systems associating solar panels and crop at the same time on the same land area". Considering the available land area between PV rows and wash out water from PV panels along with harvested rainwater from panel, few crops which can be grown in agri-voltaic system were screened based on their height, water requirement and shade tolerance characteristics. However, for future establishment of agri-voltaic system in India, performance of crops at different agro-climatic zones needs to be carried out through field experimentation.

Mini-lysimeters are generally used to quantify accurate and minor changes in amount of soil moisture content, drainage water and evapotranspiration within a soil monolith. A study has been carried out to develop a mini-lysimeter for quantification of water balance components in field in arid condition at ICAR-Central Arid Zone Research Institute, Jodhpur. The mini-lysimeter has been designed and fabricated based on electronic single load cell with a dimension of 0.50 m × 0.50 m × 0.55 m and then installed in experimental field of CAZRI, Jodhpur. The cost for fabrication of a single mini-lysimeter was 14,500 (~234.5 US $). It has been observed that fabrication of mini-lysimeter based on single load cell is less expensive as compared to conventional tank lysimeter and therefore, can be economically replicated and easily installed. The developed mini-lysimeter was tested in field during kharif season of 2014 and has been found effective to measure different water balance components with a resolution of 0.2 mm.