Estimation of the Crop Water Requirements and Crop Coefficients of Multiple Crops in a Semi-Arid Region by Using Lysimeters

Abstract

Pakistan is primarily an agricultural nation. Agriculture is the backbone of Pakistan economy and accounts for around 19.3% of its total gross domestic product. Pakistan ranks among the world’s top 10 producers of wheat, maize, rice, cotton, and sugarcane, according to the United Nations Food and Agriculture Organization (FAO). It also cultivates edible oil seed crops. Water is the most important element for the cultivation of various crops. Pakistan is a country where irrigation water is extremely valuable. The irrigation schedule affects a crop’s agronomic and economic viability. For the sake of water conservation as well as enhanced crop yields, a correct irrigation schedule is essential. Based on monitoring the soil water levels and crop water requirements, irrigation scheduling can be used to apply water for cultivation in accordance with predefined programs. How much water to apply to a particular crop and when depends heavily on the kind of soil and on the weather circumstances and is an important practical component of irrigation. Crop water requirements and crop coefficients are the most significant parameters that must be determined precisely locally to determine how much water is required for crop growth at various stages. There are many approaches for determining a crop water requirements, but lysimeters are the most effective devices. Lysimeters are devices that are routinely used to determine agricultural water requirements all around the world. The water required by different crops such as wheat, oat, carrot, and maize at different growth stages was determined using non-weighing-type lysimeters in this study. To compute the crop coefficient, the Penman–Monteith equation was used, which takes into account the daily mean temperature, wind speed, humidity, and solar radiation as inputs to the equation. The reference values for evapotranspiration during this period were obtained from a metrology station. The water requirement of the wheat varieties Fakhre Bhakhar and Anaj-17 were 361.8 mm and 379.5 mm, and their crop coefficient (Kc) values were between 0.79 and 1.19 and 0.27 and 1.27, respectively. The water required by carrot was 94.42 mm, and its crop coefficient was between 0.82 and 1.16. The water requirement of a maize hybrid variety was found to be 403.07 mm, and its crop coefficient was between 0.62 and 1.07. The water required by oat throughout its growth season including three harvests was 331.89 mm, and its crop coefficient was between 0.66 and 1.13. The water requirements of each crop and the crop coefficients calculated in this study are close to those recommend by FAO.