Determination of Silage Maize Crop Coefficient under Pulsed Drip Irrigation using Water Balance Method in Varamin

Document Type : Research Paper


1 PhD Student,, Water Management and Engineering Department, Collage of Agriculture, Tarbiat Modares University, Tehran

2 2. Associate Professor, Water Management and Engineering Department, Collage of Agriculture, Tarbiat Modares University, Tehran, Iran

3 Professor, Water Management and Engineering Department, Collage of Agriculture, Tarbiat Modares University, Tehran, Iran

4 Associate Professor, Agricultural Engineering Research Institute, Karaj, Iran

5 Graduated Student, Water Management and Engineering Department, Collage of Agriculture, Tarbiat Modares University, Tehran, Iran


Due to the scarcity of water around the world especially in arid and semi-arid regions, accurate determination of crop water requirement is essential for proper irrigation planning and management. One of the common methods for estimating crop evapotranspiration is the use of reference evapotranspiration and crop coefficient (Kc) (or the FAO-56 Kc-ETo approach). Different climatic conditions, plant variety, and differences in crops, soils and irrigation management practices result in variations in crop coefficient for the same crop between the locations, therefore locally developed Kc values are necessary for more accurate estimation of crop evapotranspiration. The aims of this research were to estimate silage maize crop coefficient using water balance method under pulsed drip irrigation system during two growing seasons (spring and summer) and to develop an equation to calculate silage maize crop coefficient based on growing-degree-days in Varamin. Silage maize actual evapotranspiration based on water balance method was 465 and 373 mm for spring and summer growing seasons respectively. Silage maize crop coefficient for initial, mid and late growth stages of spring and summer growing seasons were calculated 0.24-0.27, 1.28-1.3 and 0.8-0.88 respectively. The results showed that using silage maize crop coefficient proposed by FAO-56 caused 8% underestimation in crop evapotranspiration. Significant difference ( ) was found between  and , while using the equation presented in this study estimates silage maize evapotranspiration reasonably well, with the mean absolute error (MAE) of 0.53 mm/day, the root mean square error (RMSE) of 0.7 mm/day and the agreement index (d) of 0.98. Therefore, using developed regionally based and growth-stage-specific Kc helps in irrigation management and provides precise water applications for this region.


Allen, R. G., Pereira, L. S., Raes, D., and Smith, M. (1998). Crop evapotranspiration-Guidelines for computing crop water requirements-FAO Irrigation and drainage paper 56. Fao, Rome300(9), D05109.
Bastidas, A. M., Setiyono, T. D., Dobermann, A., Cassman, K. G., Elmore, R. W., Graef, G. L., and Specht, J. E. (2008). Soybean sowing date: The vegetative, reproductive, and agronomic impacts. Crop Science48(2), 727-740.
Dadkhah, A. (2017). Determination of Actual Evapotranspiration and Crop Coefficient of Maize with Soil Water Balance Method Under Drip-tape Irrigation Management. Master’s Thesis. Isfahan University of Technology. (In Farsi)
DehghaniSanij, H., Kanani, E., and Akhavan, S. (2020). Evapotranspiration and components of corn (Zea mays L.) under micro irrigation systems in a semi-arid environment. Spanish journal of agricultural research18(2), 26.
Djaman, K., and Irmak, S. (2013). Actual crop evapotranspiration and alfalfa-and grass-reference crop coefficients of maize under full and limited irrigation and rainfed conditions. Journal of Irrigation and Drainage Engineering139(6), 433-446.
Djaman, K., O’Neill, M., Owen, C. K., Smeal, D., Koudahe, K., West, M., ... and Irmak, S. (2018). Crop evapotranspiration, irrigation water requirement and water productivity of maize from meteorological data under semiarid climate. Water10(4), 405.
Doorenbos, J. (1975). Guidelines for predicting crop water requirements. Food and Agriculture organization. Rome, Irrig. Drainage pap.24.
Gao, Y., Duan, A., Sun, J., Li, F., Liu, Z., Liu, H., and Liu, Z. (2009). Crop coefficient and water-use efficiency of winter wheat/spring maize strip intercropping. Field Crops Research111(1-2), 65-73.
Ghorbanian, M., Liaghat, A.M, and Noory H. (2016). Investigation the Effect of Adding Fertilizer on the Crop Coefficient, Growth of Roots and Shoots of Maize Forage. Iranian Journal of Irrigation and Drainage, 6(9), 842-853. (In Farsi)
Howell, T. A., Evett, S. R., Tolk, J. A., Copeland, K. S., Dusek, D. A., and Colaizzi, P. D. (2006). Crop coefficients developed at Bushland, Texas for corn, wheat, sorghum, soybean, cotton, and alfalfa. In World Environmental and Water Resource Congress 2006: Examining the Confluence of Environmental and Water Concerns, 1-9.
Irmak, A., and Irmak, S. (2008). Reference and crop evapotranspiration in South Central Nebraska. II: Measurement and estimation of actual evapotranspiration for corn. Journal of Irrigation and Drainage Engineering134(6), 700-715.
Irmak, S. (2005). Crop evapotranspiration and crop coefficients of Viburnum odoratissimum (Ker.-Gawl). Applied Engineering in Agriculture21(3), 371-381.
Irmak, S., Istanbulluoglu, E., and Irmak, A. (2008). An evaluation of evapotranspiration model complexity against performance in comparison with Bowen ratio energy balance measurements. Transactions of the ASABE51(4), 1295-1310.
Irmak, S., Odhiambo, L. O., Specht, J. E., and Djaman, K. (2013). Hourly and daily single and basal evapotranspiration crop coefficients as a function of growing degree days, days after emergence, leaf area index, fractional green canopy cover, and plant phenology for soybean. Transactions of the ASABE56(5), 1785-1803.
Irmak, S., Payero, J. O., Martin, D. L., Irmak, A., and Howell, T. A. (2006). Sensitivity analyses and sensitivity coefficients of standardized daily ASCE-Penman-Monteith equation. Journal of Irrigation and Drainage Engineering132(6), 564-578.
Kang, S., Gu, B., Du, T., and Zhang, J. (2003). Crop coefficient and ratio of transpiration to evapotranspiration of winter wheat and maize in a semi-humid region. Agricultural water management59(3), 239-254.
Li, Y. L., Cui, J. Y., Zhang, T. H., & Zhao, H. L. (2003). Measurement of evapotranspiration of irrigated spring wheat and maize in a semi-arid region of north China. Agricultural Water Management61(1), 1-12.
Mohammadi, S., Mirlatifi, S.M., Dehghanisanij, H., and Homaee, M. (2020). Effects of Pulsed Management in Drip Irrigation on Yield, Yield Components and Water Productivity of Silage Maize. Iranian Journal of Soil and Water Research, (In Farsi)
Parkes, M., Jian, W., and Knowles, R. (2005). Peak crop coefficient values for Shaanxi, North-west China. Agricultural water management73(2), 149-168.
Payero, J. O., and Irmak, S. (2011). Daily crop evapotranspiration, crop coefficient and energy balance components of a surface irrigated maize field. Evapotranspiration-From Measurements to Agricultural and Environmental Applications. Rijeka, Croatia: InTech, 59-78.
Payero, J. O., Tarkalson, D. D., Irmak, S., Davison, D., and Petersen, J. L. (2008). Effect of irrigation amounts applied with subsurface drip irrigation on corn evapotranspiration, yield, water use efficiency, and dry matter production in a semiarid climate. Agricultural water management95(8), 895-908.
Pereira, L. S., Paredes, P., and Jovanovic, N. (2020). Soil water balance models for determining crop water and irrigation requirements and irrigation scheduling focusing on the FAO56 method and the dual Kc approach. Agricultural Water Management241, 106357.
Piccinni, G., Ko, J., Marek, T., and Howell, T. (2009). Determination of growth-stage-specific crop coefficients (KC) of maize and sorghum. Agricultural water management96(12), 1698-1704.
Raes, D., Steduto, P., Hsiao, T. C., and Fereres, E. (2018). AquaCrop Reference manual (Version 6.0), Chapter 3. FAO, Rome, Italy.
Suyker, A. E., and Verma, S. B. (2009). Evapotranspiration of irrigated and rainfed maize–soybean cropping systems. Agricultural and Forest Meteorology149(3-4), 443-452.
Trout, T. J., and DeJonge, K. C. (2018). Crop water use and crop coefficients of maize in the great plains. Journal of Irrigation and Drainage Engineering144(6), 04018009.
Tyagi, N. K., Sharma, D. K., and Luthra, S. K. (2003). Determination of evapotranspiration for maize and berseem clover. Irrigation Science21(4), 173-181.
Yoder, R. E., Odhiambo, L. O., and Wright, W. C. (2005). Effects of vapor-pressure deficit and net-irradiance calculation methods on accuracy of standardized Penman-Monteith equation in a humid climate. Journal of irrigation and drainage engineering131(3), 228-237.