Engineering and Technology Journal

The objectives of the study are to predict the crop coefficient for Maize using watermarks gypsum blocks and atmometer apparatus during the growing stages, 2013, compare the estimating values with Food and Agriculture Organization in United Nations (FAO) and local study work. Thestudy work was conducted in the Al-Yusufiya field Township, 30km south of Baghdad under semi- arid weather conditions. The watermarks and atmometer were used to measure crop evapotranspiration and reference evapotranspiration, respectively. The predicted average value of crop coefficient for initial, develop, mid and late of seasons were: 0.14, 0.6, 0.91 and 0.57, respectively. The results from the comparison between the estimating crop coefficient and FAO values showed that the average values of relative error was36.29%and with mean absolute error was0.27. Moreover, root mean square difference was0.32.Additionallythe comparison between the estimating crop coefficientswith the local study values showedthat the average values of relative error was33.57% and with mean absolute error was 0.24. Moreover, the root mean square differencewas 0.29.

The objectives of the study are to predicate crop coefficient (Kc) for eggplant using watermarks gypsum blocks and atmometer (or ETgage) devices during the growing season and to compare the predicating values of the crop coefficient with FAO recommended Kc and with local study values. The study was conducted in the field within Al-Yusufiya Township, 30km south of Baghdad under semi- arid weather conditions. The watermarks and atmometer were used to measure crop evapotranspiration (consumptive use) and reference evapotranspiration respectively. Watermarks wereinserted in the root zones of eggplant staring from the time of planting till harvest time, with the same time the atmometer was installed in the same field after evaluation and comparison was done with the FAO-56 modified Penman – Monteith equation. Comparison between the predicating crop coefficient that obtained from crop evapotranspiration and reference evapotranspiration and the recommended FAO for Kc values showed thatthe relative error was29.61%, and with mean absolute error was0.2. Moreover, root mean square difference was 0.25. Additionallythe comparison between the predicating crop coefficient with the local study for Kc values showed a relative error of 36.91% and with mean absolute errorwas 0.26.Moreover, the root mean square differencewas 0.31.